Marine Geology of Astoria Deep-Sea Fan

AN ABSTRACT OF THE THESIS OF

CARLTON HANS NELSON for the Ph. D, (Name) (Degree)

inOCEANOGRAPHY presented on _j _ (Major) (Date) Title: MARINE GELGY OFSTORIA DEEP-SEA FAN Abstract approved: Redacted for privacy JohnV. By

Astoria Fan lies on the continental rise off Northern Oregon and has its apex near the mouth of Astoria Canyon.The fan has an asymmetrical shape, evidently because the structurally controlled Cascadia deep-sea channel borders it and because the fan valleys have migrated southward ("left") during the fan construction. A few narrow, deep channels occur on the steep upper fan (gradient < 1:100) and these divide into many depositional distributaries on the flatter middle and lower fan (gradient 1:400 to> 1:1000).The olive gray postglacial clay, which is characterized by radiolarian fauna, is one meter thick in interchannel regions and more than five meters thick in main channels.Underlying the postglacial clay is a late glacial gray silty clay that contains numerous gravel, sand and silt interbeds (coarse layers), and that has a dominant fauna of planktonic foraminifera. Hemipelagic fan deposits are characterized by high clay and faunal content,, and are dominant in the postglacial section.Coarse layers deposited by density currents are distinguished by dominance of Columbia River detrital minerals and displaced benthic foraminifera, moderate sorting, grading of size and composition, and typical turbidite sequence of sedimentary structures.Thetail" deposits from density currents are characterized by clayey-silt size and by a coarse fraction of platy constituents (mica and plant fragments). Denity-current deposition predominates in the late-glacial sediments. Fan ash layers are correlated with continental deposits from the cat3clysmic eruption of Mt. Mazama 6, 600 B. P. by position in the stratigraphic column, refractive index, and radiocarbon dating. Textural and compositional gradation, Columbia River mineral suites, and upper slope fauna within the tuffaceous layers indicate that ash was spread throughout the fan by density currents. Thickness and distribution of the tuffaceous layers and coarse layers reveal that transportation and deposition of the main, coarsest portion of density currents is restricted to fan valleys and distributaries; fine, sorted "tail" debris spreads beyond even the deepest channels (> 100 fathoms) and builds upper fan interchannel regions.High coarse layer:shale ratios throughout the main fan valleys and the middle and lower fan result from this density-current depo sition. Because of density-current processes, proximal regions of the fan can beidentified by the low coarse layer:shale ratios in interchannel regions, by, poorly, sorted, massive, and gravelly coarse layers, andbya stratigraphy of coarse beds with sharp upper contacts, irregularthickness, and poorly developed clay partings. Away from the proximal regions, coarse layers progressively: (1) decrease in skewness, and content of clay, platy constituents, and heavy minerals, (2) increase in content of detrital minerals, (3) have better sorting, and. development of sedimentary structures.Herni- pelagic deposits grade out from the continental terrace and Columbia river plume, which is the source of clay; they contain more clay and planktonic remains, but less terrigenous debris toward the open ocean. The aforementioned data of Astoria Fan provide criteria for a fan model that helps in identifying fan deposits of the geological record, and that permits speculation on the history of Astoria Fan. In the Pleistocene, deep channels were eroded in the upper fan into older clays with "ice rafted(?)" pebbles.Coarse density-current debris was funneled through the channels to depositional distributaries of the middle and lower fan1With shift of the shoreline to the east, which is shown by change to finer texture and greater planktonic composition of the postglacial hemipelagic sediments, and with rise of sea level, density-current activity slackened.In thepost- glacial,period influxofivlazama ash provided material for the last large density currents on the fan; it also may have contributed to rapid filling of fan valleys which is indicated by the following sedimentation rates calculated from faunal reversal and Mazama ash horizons: Channel Interchannel Postglacial 25 cmjlO'3 yrs 8 cm/tO3 yrs Pleistocene > 40cm/tO3yrs Based on observed sedimentation rates, present sediment loads of the Columbia River, and seismic thickness of unconsolidated fan sediments, it appears that the fan was built mainly during the Pleistocene. Marine Geology of Astoria Deep-Sea Fan

by Canton Hans Nelson

A THESIS submitted to Oregon State University

in partial fulfillment of the requirements for the degree of Doctor of Philosophy June 1968 APPROVED: Redacted for privacy Pr essor of Oce graphy in charge of major

Redacted for privacy irman of Delartment of Ocgraphy

Redacted for privacy

DeanbiGraduate School

Date thesis is presented c'cN \))\T_ Typed by Marion F. Palmateer ACKNOWLEDGEMENTS

I would like to express my appreciation to my major professor, Dr. John V.. Byrne, for:his guidance throughout the project, andfor his critical review of the manuscript and figures. Dr. Vern Kulm provided considerable assistance in perfecting techniques of piston.coring,and sediment size analysis.Dr. Gerald Fowler confirmed identification of and depth ranges for for.ammnifera species.The help of Sue Bordon. in computer programming and. data processing is gratefully acknowledged. Many, beneficial discussions were held with the aforementioned faculty members and the following graduate students: Paul Carison, Erwin Runge, John Duncan, Gary.Griggs, Dick Boettcher, Jim Ridlon, Dave Allen,. and Arthur Hunger.I would. like to express my gratitude to all of these people and,.to the crews of the R. V. Acona and the R. V. Yaquina.. for help with the difficult task of collecting piston cores. The author also wishes to express great. appreciation to his wife, Jane, for many.hours spent typing, drafting,. and editing the disserta-

tion, .and. for her helpand encouragement throughout the entire course of study. This study was madepossible 'through the financial support of the office of' Naval Research (Contract Nonr1286 (10) and the research facilities of the Oceanography.. Department, Oregon State Tjniver sity. TABLE OF CONTENTS Page

L INTRODUCTION 1

Purpose 1 Previous Work 3

II. GEOLOGIC SETTING 5

Continental Geology 5 Columbia River Drainage 6

IlL, OCEANOGRAPHIC SETTING 8

General 8 Water:Masses 8 Currents 9 Biological Oceanography 14

IV. PHYSIOGRAPHY 16

General 16 Continental Terrace 16 Astoria Canyon 17 Astoria Fan 18 Channel Systems of Astoria Fan 28 Comparison of Astoria Fan Valleys with Astoria Canyon, and Cascadia Channel 36 Comparison of Astoria Fan Valleys with Other Fan Valleys 37 Comparison of Astoria Fan with Other Deep-sea Fans 39 Astoria Fan Compared with Alluvial Fans 43

V. SEDIMENTS 45

Sampling Methods 45 General Stratigraphy of the Fan 48 Lithology, Texture, andCoarse Fraction of Sediment Types 52 Composition 78 Summary of Characteristics of Displaced Foraminifera 86 Comparison with Coarse Layers of Other Regions 109 Page

VL STRATIGRAPHY 114

Correlation and Age of the Stratigraphic Units 114 Establishment of a CorrelatingAsh Horizon 117 Summary of Astoria Fan Stratigraphy 124 Comparison with Stratigraphy of Other Regions 126

VII. SOURCEOF SEDIMENTS 131

Terrigenous Materials 131

VIII. SEDIMENTARY PROCESSES 138

Hem ipelagic Sedimentation 1 38 Transportation and Deposition of Exotic Materials 139 Other Sedimentary Processes 151

IX. RATES OF DEPOSITION 157

General 157 Interchannel Regions 160 Channels 161 Sedimentation Rates Compared with Other Regions 162

X. GEOLOGIC HISTORY OF ASTORIA FAN 166

History of the Region 166 Sequence of Events in Astoria Fan History 169 Estimates of Astoria Fan Age 177 Age of Fan Based on Sedimentation Rates 179

XI. GEOLOGIC SIGNIFICANCE 186

General Characteristics of Fans 186 Review of the Density-Current Process 187 Significance of Deep-sea Fans in Geologic History 193 Application to Ancient Rocks 198

BIBLIOGRAPHY 208

APPENDICES 225 LIST OF FIGURES Figure Page

1 Submarine and continental physiographic features in the vicinity of Astoria Fan. 2

2 Sample station locations and bathymetric sounding lines completed on Astoria Fan. 19

3 Bathymetric chart of Astoria Fan, 20

4 Transverse profiles of Astoria Channel and Slope Base Fan Valley. 22

5 Physiographic divisions and fan valley systems of Astoria Fan.

6 Longitudinal profiles and Precision Depth Recorder profiles of Astoria Fan. 25

7 Physiography of the apex region of Astoria Fan. 29

8 Sediment types of Astoria Fan. 47

9 Thickness of brown clay and of olive gray clay. 49

10 Representative lithology of Astoria Fan. 51

11 Relation between sorting versus mean grain size, physiographic location, and coarse fraction content of Astoria Fan coarse layers. 56

12 Relation between sorting versus mean grain size, physiographic location, and coarse fraction content of fine-size sediments of Astoria Fan. 57

13 Relation between skewness versus mean grain size and stratigraphic units of Astoria Fan sediment types. 58

14 Sand-silt--clay content of sediment types in the various physiographic regions of Astoria Fan. 59

15 Terrigenousplaty-terrigenous, and biogenous content of sediment types in the various physiographic regions of Astoria Fan. 60 LIST OF FIGURES (continued) Figure Page

16 Representative cumulative size frequency curves for Astoria Fan sediment types. 62

17 Triangular diagram of the light mineral fraction of Astoria Fan sediments 80

18 Lateral changes with distance from the continental slope in surface postglacial olive gray clay and glacial gray silty clay. 89

19 Gradation of clay percentage in surface sediments of Astoria Fan. 90

20 Gradation of coarse fraction terrigenous debris in surface sediments of Astoria Fan. 91

21 Coarse fraction composition of surface sediments from the continental slope to Cascadia Channel. 92

22 Textural gradation with distance from the fan apex in the coarsest layer at each core location. 100

23 Representative sedimentary structures of Astoria Fan coarse layers. 104

24 Coarse layer from lower Astoria Channel (core 6509-4) illustrating Bouma (1962) sequence of turbidite sedimentary structures. 105

25 Gradation of coarse fraction and sand content in typical Astoria Fan coarse layers. 106

26 Gradation of coarse fraction, sand content, and displaced benthic foraminifera in a thick sand layer of lower Astoria Channel. 107

27 Comparison of Astoria Fan and Cascadia Abyssal Plain channel and interchannel lithology and stratigraphy. 115

28 Distribution, depth, thickness, and quantity of volcanic glass in representative ash layers of Astoria Fan. 118 LIST OF FIGURES (continued) Figure Page

29 Areal distribution of Mazama ash. 119

30 Vertical distribution and age correlation of Mazama ash in selected cores from the deep-sea floor off Oregon. 121

31 Sedimentation rates of Astoria Fan. 158

32 Characteristics of a deep-sea fan model. 199

33 Coarse layer:shale ratios for late glacial and postglacial sediments of Astoria Fan. 202 LIST OF TABLES

Table

1 Direct Current Measurements within 5 m. of the Deep-sea Bottom 13

2 Dimensions of Astoria Channel and the Slope Base Fan Valley on Transverse Profiles Throughout Astoria Fan 27

3 Dimensions of Main Fan Valleys (to 1250 fathoms) of the Astoria Fan Apex 31

4 Dimensions of Representative Submarine Fans of the World 40

5 Summary of Textural Characteristics of Fan Sediment Types 53

6 Summary of Coarse Fraction Characteristics of Fan Sediment Types 54

7 Physiographic Distribution of Sandstone Types of 22 Representative Coarse Layers from Astoria Fan 79

8 Average Amounts of Coarse Layer Lithology in Different Physiographic Regions of Astoria Fan 99

9 Vertical Gradation of Composition and Texture in Coarse Beds of Astoria Fan and Other Recent Sediments and Rocks from Similar Environments 110

10 Comparison of Proximal and Distal Stratigraphy of Astoria Fan 125

11 Summary of Light Mineral Analyses 132

12 (a) Summary of Astoria Fan Heavy Mineral Analyses; (b) Pyroxene/Amphibole Ratios for Sediments of Astoria Fan and Adjacent Areas 133

13 Summary of Sedimentation Rates on Astoria Fan 159

14 Total Sedimentation Rates in Regions Near Astoria Fan and in Similar Marine Environments 163 MARINE GEOLOGY OF ASTORIA DEEP-SEA FAN

L INTRODUCTION

Purpose

Astoria Fan is located at the base of the continental slope off the northern coast of Oregon (Figure 1).The Fan apex orignates at the mouth of Astoria Canyon which heads off the mouth of the

Columbia River.The prism of sediments constituting the fan forms part of the continental rise, which is the lowest part of the continental margin(Heezen and Menard, 1963). History of continental rise sediments in this transition region between continental terrace and the deep sea recently has been of great interest to marine geologists.Knowledge from this region where continental and oceanic crust meet is needed to understand mechanisms of possible continental drift, sea floor spreading, and continental accretion.In this region at the base of the continental slope great quantities of land derived sediments are known to ac- cumulate.Study of continental rocks indicates that some of these deep-sea sediments may eventually be added to the continents.Con- sequently, knowledge of depositional history of present continental rise sediments can be applied for the uiderstanding of continental rocks with a similar history. I32 100 128 26 I24 ZQ lIb JI'r 1 I :1 SUBMARINE FEATURES MOUNTAINS - HILLY AREAS DEPRESSIONS )200 F'MSO 50 O, (I) ABYSSAL PLAIN CONTOUR INTERVAL 100 FATHOMS . LAND FEATURES

- DRAINAGE DIVIDES ...... -. o (7 Thesis Area

flIVE, 48 48 LU J. OLYMPIC

MTNS . (7 4 CASCADIA 0 C, ...... C'

ciTMe'

- PLN o

I :...:. : . KLAMATI 42 42 MTNS

BASIN-RANGE

MENDOCINO FRAC ZONE\ I I I I 32' 30' 28' 26' 24' 22' 20' 118' 16' 114' 112' 10' Figure 1,Submarine and continentalphysiographicfeatures in the vicinity of Astoria Fan, 3 To help understand present and past environments this dis' sertation studies the sediments, the sedimentary processes, and the history of Astoria Fan.Progressive changes in physiography, stratigraphy, texture, and composition can be traced from the mouth of Astoria Canyon which has served as a point source for much of the fan sediment. By ascertaining trends of such parameters in the unconsolidated sediments, the depositiona]. history of similar sedimentary rocks may be better understood.

Previous Work

Bathyrnetry, geomorphology, and recent sediments of the Northeast Pacific have been studied by Menard (1953, 1955), Nayudu (1959), and Hurley (1960), but no detailed investigation of Astoria Fan has been made by anyone.The most recent geologic work related to Astoria Fan has been accomplished by the Oceanography Departments of the University of Washington and o Oregon State University.Royse (1964) made a detailed study of sediments in Willapa Canyon a few miles north of Astoria Canyon.Sediments and radioactivity in the vicinity of the columbia River effluent have been reported by Gross, McManus, and Creager (1963), Osterberg, Kulm, and Byrne, (1963), and Gross and Nelson (1966). A cursory analysis of the micro-fossils was made for a very few surface sedi- rnent samples from the Astoria Fan region by Nayudu and 4

Enbysk (1964).In a paper on regional physiography McManus (1964b) outlined the major bathymetric features of the fan.He also described surface sediment color in a few samples from Astoria Fan,(McManus, 1964a). Recent research at Oregon State University has outlined characteristics for the regions near and adjoining Astoria Fan. The continental terrace bathymetryand shelf sediments along the Oregon coast have been analyzed by Byrne (1962, 1963a, 1963b) and

Runge (1965).Maloney (1965) studied the bathymetry and sediments of the shelf and slope off the Central Oregon coast, and Byrne, Fowler and Maloney(1966) reported onthe uplift and possible continental accretion in this region.Adjacent to Astoria Fan, the bathymetry and sediments of Astoria Canyon have been examinedby Carlson (1967); Kuim and Griggs (1966) have reported on sediments of Cascadia Channel; and Kuim and Nelson (1967) have compared channel and interchannel deposits. 5

ILGEOLOGIC SETTING

Continental Geology

Numerous small streams and rivers which empty dir ectly into the Pacific Ocean, drainthe west slopes of the Coast Range. Rocks of the Oregon Coast Range (Figure 1) include a lower sequence of thick submarine volcanic flows of early Eocene age and an upper sequence of tuffaceous sedimentary rocks of Eocene to

Pliocene age (Snavely and Wagner,1964). The sedimentary group consists mainly of micaceous and arkosic sandstones and sandy siltstones.Sedimentary rocks similar to those appear to extend to the shelf and slope offshore (Byrne,1963). Maloney(1965)and Fowler

(1966)reported finding diatomaceous and clayey siltstones, and calcareous siltstones of Upper Miocene and Pliocene age. To the east of the Coast Range is a structural depression, the Puget Sound-Willamette Valley Trough (Figure 1).This region is underlain mainly by Tertiary sedimentary and volcanic rocks and is drained by tributaries of the Columbia River(Baldwin,1964). Inland from the trough lie the Cascade Mountains.The older Western Cascades are composed mainly of basalts that were laid down from Eocerie toMiocene time (Baldwin,1964). The High Cascades formed since the Plioceneandwere built mainly from andesitic flows and pyroclastics. (Williams, 1942). East of the Cascade Range the Columbia Plateau basalts cover an area of about 200, 000 square miles.These are fissure flows of olivine and tholeiitic basalts that poured out during the Miocene

(Waters,1955and1961). To the east of the Columbia Plateau are the northern Rocky Mountains.These are mainly folded and faulted metamorphic and sedimentary rocks, except for the granitic Idaho batholith.

Columbia River Drainage

Development of the modern Columbia River drainage probably began in the Miocene (Mackin and Gary,1965). The Columbia River gOrge cuts through the Cseades and Coast Raige zhich indicates that the present drainage pattern of the Columbia was developed by the time of the Plio-Pleistocene uplift of these mountains. The lower Columbia River may have had caitastiiophic: floods during the Pleistocene when ice dams forming Lake Mis soula broke and released meltwater of the continental glaciers (Bretz etal.

1956). The last catastrophic flood is believed to have occurred during Pinedale glaciation 18, 000 years B. P. (Richmond etal.,1965). These authors feel that extensive flooding in the Columbia River valley took place until 12, 000 years B. P.Flooding in the pre- historic Post-Pleistocene may have been comparable to that observed 7 by the U. S. Army Corps of Engineers during the past 100 years. The present Columbia River is the largest riverin thePacific Northwest and third largest river in the United States (Higlismith,

1962).It drains all of theaforementioned geologic provinces (Figure 1) and the:resu1ting discharge and sediment load carried to the Pacific Ocean is very large and complex. Annual discharge of the Columbia River is approximately 180 million acre feet (7.8 x1012cubicfeet) of water (Lockett, 1965). Maximum discharge up to 1, 240, 000 cfs (cubic feet per second) (U. S. Army Engineers, 1961) occurs in the early summer because of melting snow in the Cascades and Rockies. Major flood conditions (750, 000 cfs) have occurred2O times in the last 100 years and floods over 1, 000, 000 cfs have occurred on an average of once every 25 years. The average annual amount of suspended sediment transported toward the seaby the Columbia River is approximatelyl4, 500, 000 cubic yards (U. S. Army Corps of Engineers, 1962).Lockett (1965) reported an average annual bed load of 4,000, 000 tons (1, 780, 000

Cu.yards) at the Vancouver, Washington station. F;'

IlL OCEANOGRAPHIC SETTING

General

Oceanographic conditions are of considerable importance to the sedimentation of Astoria. Fan.Currents and water,masses determine the distribution of biota and suspended sediments that filter through the water column.Currents along the bottom affect the erosion, transportation, and. deposition of sediments.The physical and chemical properties of the water. influencethe distribution and abundance of planktonic organisms in the water column.Planktonic productivity in turn,, affects. the number and kinds of benthonic animals that rework and. alter the sediments.

Watery Masses

The most extensive water mass off the Oregon coast is referred toas'ModifiedSubarcticWater (Rosenberg, 1962).It consists mainly of Subarctic Water, (2° to40and 32 0/00-34 o/oo) mixed with a small amount of Pacific' Equatorial Water (8-15°C and

34. 60/00-35.20/00)(Sverdrup, Flrning, and Johnson, 1942).In- shore, over the continental terrace, the percentage of Equatorial Water increases and this modified water is called Coastal Water (Rosenberg, 1962).As a rsu1t of streams and rivers discharging into the ocean, inshore surface'water is somewhat diluted in many areas. The Columbia Riverintroduces the greatest quantity of fresh water into the ocean along the Oregon coast.At sea the Columbia River effluent is confined to the upper 40 meters of water,

(Budinger, Coachman2 and Barnes, 1964) and can dilute the nearshore waters to a salinity below 32 o/oo (Morse and McGary, 1965). Budinger etal. (1964) reported that during the summer he effluent extends south from the mouth of the river some 750 kilometers to near 40° N Latitude, and that the western boundary was 210 kilometers from shore.Osterberg, Cutshall, and Cronin(1965) traced the Columbia plume only. 350 krnsouth in the summer; they, found that in the winter the effluent occupies a belt 30 to 55 kilometers wide adjacent to the continent and extends from about 40 kilometers south of the mouth of the Columbia River to north of the Strait of Juan de Fuca.

Currents

Nearshore Currents

Winds are predominantly from north to northwest during the spring and summer months, and the California Current System dominates with current and littoral drift to the south (Lane, 1965). These northerly, winds also cause the surface coastal water 'to be l0 carried offshore by Ekman transport which results in upwelling

(Smith,1964). During the fall and winter the winds are predominantly from the south-southwest and the littoral drift is to the north. Upwelling ceases in the fall and a counter-current develops in the surface layers, the Davidson Current; this current carries water:. from the south to the north along the coast (Burt and Wyatt,1965). Recently, current velocity, and. direction data have been collected over the continental terrace off central Oregon by means of current drogues, and by current meters moored to buoys and to oil drilling barges (Collins, Creech, and Pattullo, 1966). Current meters,about 20 m above the continental shelf seafloor, measured maximum current velocities of 73 cm/secat60m depth and 61 cm/sec at 75 m depth during the winter (Collins, Creech, and

Pattuilo, 1966). Maximum velocities at similar depths in other sea- Sons of the year were much lower.In water 200 to 1000 m above the continental slope, currents ranged from 3.4to 7. 0 cm/sec with the exception of one reading of14cm/sec (Stevenson,1966). At 1000 meters, Stevenson(1966)found a mean speed of 4 cm/sec.These data suggest that sand-size material occasionally may be carried by shelf currents beyond the nearshore zone, but that sand-siz.e-- thaterial i's not carrie.d 'by currents in the deep sea. .. Upwelling currents and tidal currents, as well as wind driven currents, may influence distribution of organic remains and inorganic 11 sediments (Cartwr&ght, 1959).Tidal current speeds from 4. 0 cm/sec over Stonewall Bank to 7. 5 cm/sec off Depoe Bay, Oregon suggest that tidal currents have little effect on sediment distribution off Oregon (Pattullo,1966). Likewise, very low average speeds

(<. 01 cm/sec) calculated for upwelling (Smith,1964)show that these currents are insignificant for sediment transport.However, deep water chemical and physical characteristics are measured in surface water to nearly. 100 km offshore during the summer months (Park, Pattullo, and Wyatt, etal., 1962); this indicates that upwelling may affect productivity, and, consequently, organic depo sition over the shelf.

Bottom Currents

Measurements of deep-sea bottom currents off Oregon7 are the most pertinent for this study, but only scant data are available.

Carruthers (Personal communication,1965),using a current meter of unproven reliability, reported a bottom current of 0. 7 knots 170 miles west of the mouth of the Columbia River on CascadiaAbyssal

Plain just west of Astoria Fan. Mesecar(1967)measured steady bottom currents over a 24 hour period of6cm/sec at 100 fathoms over the continental slope west of Depoe Bay, Oregon Measured current velocities less than five meters above the deep-sea bottom generally are lower than sea floor velocities 12 assumed from deepsea current studies (Table 1) and used for geological inference (Heezen and Hollister, 1964a, Hubert, 1964).The highest current velocity reported less than 5 m above the bottom is 25 cm/sec in the axis. at Scripps Canyon, California (Shepard, 1965). This was not a time series study on the sea floor, but a diving saucer observation.The classical, idea of slow, steady drift along the deep-sea floor, is no longer valid; however, it is obvious that more data are necessary .to.verify the postulations of transport of coarse materials by, deep- sea. bottom currents (Knauss, 1965).

Internal Wave Currents

The effect of internal wave currents at the bottom is another phenomenon that is little known, especiaily.in the deep sea, where interactions may be different than on the continental terrace. LaFond (1961) found internal wave currents with speedsof 5-30 cm/sec in shallow waters of Southern California.These currents would be of sufficient intensity to move sandy. sediments in a seaward .d.irection (LaFond, 1961).

Seismic Seawave Cufrents

Heck'(1947) reported five seismic seawaves over a 20 year period in the Pac.ific'Northwest.These shallow water waves Hfeel the bottom" over their entire path.The seismic seawave from the 13

Table 1.Direct Current Measurements within 5 in. of the Deep-sea Bottom Water Meters Current depth above velocity Investigator Location (metersj bottom (cm/sec) Type of instrument Emery Center- 800 0.2 2.5 Ekman current meter (1956) Santa Cruz below 0.5 13.5 Ekman current meter Basin sill depth Center- Ca. 825 0. 2 2. 8 Ekman current meter San Pedro below 0. 5 18. 0 Elcman current meter Basin sill depth

Swallow. 33°07' N 3, 230 0 11. 5 ±. 1,5photographic bottom (1961) 75 42' W current meter

McAllister Bermuda 3, 760 5 6. 7 Savonius rotor (1962) Plantage- current meter net: Bank

LaFond 32°37' N 1, 180 0. 15 1-3 inclinometer attached (1962) 117°30' W av. 2.1 to Trieste

* Throndike 50 N. M. 4, 400 0. 0 7. 6 suspended drop (1963) south of current meter Bermuda

Pratt Blake 786- 0. 0 av. 25 photographic current (1963) Plateau 841 max. 47 meter (ping pong balls)

Knauss Central AtJ. Savonius meter moored (1965) (W. slope Ber- to the bottom for given muda Rise) time and then released 0 32 11' N 5, 192 3.5 14-21 68°12'W 17-mean 32°05' N 5, 182 3.5 10-15 68°12' W 12-mean 34°24' N 5, 337 3. 5 0-2 69°47' W

Gulf Stream 36°04' N 3, 584 3.5 7.5-14 73°13' W 9.7-mean

Isaacs iii. 300-800 N. M.3, 700- 3. 0 1-4 Savonius meter moored (Mooérs, 1967) off Baja, 4,300 2.2-meanto the bottom for given California time and then released

* N. M. = nautical mile 14 Alaska earthquake of March 27, 1964, had a speed of 280. knots, a period of 40 minutes, and a wave length of 294 nautical miles (Schatz,

1965).Assuming an amplitude of 0. 5 meters for this wave, Carlson (1967) calculated a particle velocity, of 35 cm/sec at 1000 fathoms. According to Sundborg (1956), this velocity could cause erosion of unconsolidatedmediumsand on the deep sea floor.

Biological. Oceanography

The same Ekman drift offshore that causes upwefling and high productivity moves phytoplankton crops away from the nearshore regions (Curl,1966). This results in zoopiankton and. benthic popula- tions having their maximum productivity offshore (Curl,1966). Maximum standing crops of :foraminifera occur in the middle shelf to upper slope area off Cape' Argo, Oregon (Boettcher,1966). Macro-fauna also are most abundant at the shelf-slope break off Newport, Oregon, but decrease to very low densities in the abyssal region (Carey,.1966). As the sediment becomes finer with depth, polychaetes (burrowing forms) increase in relative abundance over filter feeding organisms which are dominant in sands on the inner shelf (Carey, 1966).Over most of the abyssal plain polychaetes are the most important group. Distribution of organic carbon in the sediment correlates best with the polychaetedistribution (Carey, 1966), and this,in turn is 15 often related to sediment size (Trask, 1939).Gross (1966) found a maximum concentration of organic carbon on the continental slope in the Northeastern.Pacific.He attributed this to oxygen minimum layer depths rather than to the fine sediments and high biota on the upper slope. 16

1V.: PHYSIOGRAPHY

General

Astoria Fan is a wedge of sediments covering about 20, 000 km2(6, 000 sq miles) on the continental rise off the coast of Oregon (Figure 1).It is bounded on the north by Willapa Seachannel and on the west by Cascadia Channel (Figure 1).Willapa Seachannel begins north of Astoria Canyon and appears to extend from Willapa Canyon. Cascadia Channel also originates north of Astoria Canyon and Fan near the apex of Nitinat Fan (McManus, 1964b, p70).The southern boundary of the Astoria Fan is not definitive; however, beyond 1550 fathoms',the fan shape is not present and seamounts disrupt the sea floor.The continental terrace forms the eastern border of the fan region.

Continental Terrace

The physiography of the continental terrace off Oregon which consists of the continental shelf and the continental slope, has been described by Byrne (1962, 1963a, 1963b) and Maloney (1965).The continental terrace is narrower (35-60 naxticalmiles2),the

'Onefathom equals six feet. 2Alldistances expressed in miles are nautical miles. One nautical mile equals 6076. 12 feet. 17 continental shelf is steeper (0008! - 0043!), and the continental slope

10 e is flatter (northern portion 11' - 1 35') than average regions of the world (Shepard, 1963).The shelf to slope break or shelf edge generally occurs in water 80 fathoms deep; the edge of the abyssal plain, in water l000-1700fathoms deep.Shallow banks of bedrock extend the shelf to slope boundary seaward and cause the irregular outline of the shelf (Figure 1).The continental slope has a number of separate slopes and scarps interrupted by benches, depressions, and small valleys.

Astoria Canyon

Astoria Canyon, which is the only sizable submarine valley crossing the Oregon slope, has been studied by Byrne (1963) and Carlson (1967).The canyon heads in about 55 fathoms of water approximately 90 miles west of the mouth of the Columbia River,. and extends some 60 miles to a depth of 1, 140 fathoms.It is mildly sinuous and exhibits an overall orientation to the west-southwest. The average width of the canyon is 3. 8 miles with a range of 1. 3 - 7. 2 miles.The average floor width is 1. 2miles.In the area of the outer shelf, the canyon is one mile wide at the bottom,. three miles wide at the top, and has 300-400 fathoms of relief.At the canyon mouth the floor is about 0. 5 miles wide, the rim is 4. 5 miles wide nd the wall relief is 150-200 fathoms.The slope along the axis varies irregularly from 0° 31' to 3° 57', but overall the average gradient is '1°.Average steepness of canyon walls is 6° and where the canyon crosses the shelf the walls are steeper on the south side than on the north side.Along both walls precision depth records 'suggest that slumping is an important process and that maximum slopes are about 30°.These maximum values may, be below actual values. Observations of canyon walls, from submersibles (Buffington, 1964; Shepard, 1965) indicated much steeper walls.. than did previous meas urernents by depth recorders and wire line soundings.

Astoria Fan

Methods of Study

The Precision Depth Recorder (PDR, ,MarkV), coupled with an Edo (185) echo sounder,was used.for completing 1064;miles of sounding lines (Figure 2).Loran A was usedto obtain geographic posi- tions at 15 minute intervals.In addition,bathyme.try was. synthesized from data of Hurley (1960), McManusfl964b) Byrne (1963), and smooth sheets of the U. S. Coast and Geodetic Survey and the U. S.

Naval Oceanographic Office (Figure 3). . Particular' attention was given to the Astoria Canyon mouth and the fan valley systems extending from it.Soundings were obtained for a five mile grid transverse 19

-1 I I I I 1 I

J 12700 12600' 1400 300 200 1100 000

SA- 4

\j1l

C-4-2'b. 3 Ti \ LL 609-9A 0-4

S'S\ 6509-5

I550 -S S. \\ "S \ 6509 7 \ 4500' I NJ

650 - 7 6509-2 509-I ------"6509-6A 0 1600 / '., ASTOR/A " 1200 N Jl300 Nelson 111400 Ca rison 967 1500 1550 O _1 __O 6509I Piston Core and Phleger Coresample station. NAUTICAL MILES Contour Interval : 00 fathoms 50 fathoms 0 0I _J20 KILOMETERS Compiled by Hans Nelson

Figure ?,Sample station locations and bathymetricsounding lines completed on Astoria Fan, 'U

46'OO 0 -4

Cl)

45OO

Con Oceanography Deportment soundIngs, 1965. NAUTICAL MILES Hurley (1960), and Mc Mantis (1964). Contour Interval :50 fathoms (1000-1300) 0 10 20 tO fathoms (1300+) KILOMETERS by Hans Nelson

Figure 3, Bathymetric chart of Astoria Fan, 21 to Astoria Channel and the Slope Base FanValley3(Figure 2). Bathymetry of the fan valley systems was contoured from new ound- ings that were compiled and plotted by the IBM 1620 computer and the X-Y plotter (Figure 4).

General Shape

Astoria Fan, which is asyrnetriáa]i, extends about 55 miles west of the mouth of Astoria Canyon, and only about 15 miles to the north where it abuts Willapa Channel (Figures 1 and 2).Seventy-five miles south of the canyon mouth the 1550 fathom contour extends 75 miles west and is the last one to outline the shape of the fan.Some investigators extend the fan southanother 50 miles through a depression between the continental terrace and the Blanco fracture region (Figure 1; McManus, 1964b).In this study, the 1550 fathoms depth arbitrarily is defined as the fan margin because the sea: floor to the south is not fan shaped and is disrupted by seamaunts,:aaDa4ia Channels and ithe Blanco Fracture Zone.

Physiographic Divisions

Investigators generally, have divided deep-.sea fans into two

3tJnderShepard's (1965) classification both of these features are fan valleys.This term will be used in describing general channel systems of the fan, but use of the proper name for the main fan valley, Astoria Channel, will be continued. 22

26'3O' 4600' oo

Contour Interval: 10 fathoms Profile Esougerotian:20* '-Ito"' Profile PeNs!: 200 fathoms /

t m.o, Contours based on Oregon State University, Oc.onogrophy Department soundings. 1965. CompiId by lion, Nelson

t___j I? a..,, NAUTICAL9 'P MILES (INS! SLOtIETESS C____'C(I'S. ----D,

(05$! w HW______I L1L.1' ("S., \'

,' .1' Is______-.-__ -, "\ (ISO,) (IllS! (MS.!

N N

44.o'L_ M830

Figure 4.Transverse profiles of Astoria Channel and Slope Base Fan Valley. 23 parts, theupper:and the lower. (Heezen and Menard, 1963; McManus,

1964).Detailed analysis indicates that Astoria Fan can be divided into three regions on the basi,s of gradient, relief, and character of the slope (Figure8 5 and 6).The upper fan is a region of relatively deep, narrow fan valleys, steep slope, and rough topography.The middle fan has fan valleys that begin to broadenand split into distributaries, a fan gradient that flattens sharply from the upper fan, and a relief that is less than half that of the upper fan.The lower fan is a region of nearly flat topography, with shallow distributaries. Lower fan gradients in some places become less than those ofabys-. sal plains.

Upper Fan

The upper fan includes the region from the mouth of Astoria Canyon to 1330-. 1390 fathoms.In the northwest and west portions of the fan the break in gradient occurs from 1370-1390 fathoms; in the southern part of the fan it usually takes place near 1340 fathoms. The surface of the upper fan is mainly concave upward (Figure 6). The upper fan; is generally, steeper and has rougher topography than that cited for most fans (Heezen and Menard, 1963).Relief of 10-20 fathoms is not uncommon and occasionally is up to 30 fathoms (Figure 6).In some locations, although the gradient is still very steep, the surface is smooth. 24

-4

Cr)

-4

Luj

K 450 00

()

Fist Coni Oceanography Department soundings, 1965, NSUTICAL MILES Hurley (1960). and Mc Manus (1964). Middle Fan Contour Intervol :50 fathoms (1000-1300) Upper and Lower Fan o io 20 10 fothoms (1300+) Eon Valley Systems KILOMETERS by Hans Nelson

Figure 5.Physiographic divisions and fan valley systems of Astoria Fan. +f/ I::4t L7/ .v-__ L-

6+ (\ PD R Trace Profiles

-' 01 100 Fthon Rehof -1 200.1 I

-t / 0 L.) //

----. ASTORIA .1 - .... FAN pI_ c_. a pita, C(_. ,pl. .t.t.. EI_._.______13001 °'-' c-c 0E .0

1400 -oweo

1500

Upper Fan Middle Fa Lower Fan

I I 1600o 5ONM 100 NM 93Km 185 Km Figore 6. LongltdinoInd P DR troce protilos of Astorlo Pen. 26 Gradientsinth.e upper fan range from 1:15 to nearly'l:lOO, but usually, are near'1:50 - 1:60.Slopes of the channel axis in this. region are less steep than. fan surface gradients and as a rule are less than.1:100 (Table 2).The steepest slopes are found on the fan valley walls.

Middle Fan

The middle fan extends from the break in slope at the edge of the upper fan to about 1460 fathoms in the southern region of the fan. The outer boundary of themiddle fan region is not nearly as distinctive as the upper to middle fan break. Compared to the upper and lower portions of the fan, the middle fan appears to have a convex upward surface, even in the channels. The relief, which commonly, is about ten fathoms, and the slope gradients are much lower than those on the upper fan.Themiddle fan gradient generally is between 1:250 - 1:350, but maximum slopes range to nearly'l:lOO, and the minimum gradient ranges up to about

1 :400.The channel gradients are more inclined than the normal fan surface and usually are steeper than 1:200 (Table 2).

Lower Fan

Usually,a slight break in slope marks the beginning of the lower fan, although middle, fan slopes may grade quite evenly into the lower Table 2.Dimensions of Astoria Channel and theSlopeBase Fan Valley on Transverse Profiles throughut Astoria Fan (see Figure 4) Latitude AstoriaChannel SlopeBaseFanValley of both chan- Longitude Fig. 4 Axial Axial Channel Longitude Fig. 4 Axial Axial Channel nelprofiles of profile profile depth relief Gradient of profile profile depth relief* Gradient 0 125°25.8-33.5' 1145 90-100 o o 1:113030' 45 50' 125 35-41' A 1190 80 125 31-33' A 1173 40 o 1:113 30' 1:78 0°44' 45 45' 125 36-41' 1235 70 125 26-33' 1238 70 o o 1:113 30' 1:11230' 45 46' 125 36-39' B 1280 70 125 26-31. 5' V 1282 70 o 1:250 14' 1:17420' 45 35' 125 39-43' C 1300 55 125 27-31' U 1311 30 o o 1:137 25' 1:12927' 45 30' 125 43. 5-47' D 1337 40 125 25. 5-35. 5' T 1350 35 o o 1:108 32' 1:19618' 45 25' 125 50-52.5 E 1384 45 *125 00-45' S 1383 31 o o 1:195 18' 1:13725' 45 20' 125 51' F 1410 30 *125 33. 1_45r R 1420 35 o 1:126 27' o 45 15' 125 35-51' G 1450 32 125 22-27' 1396 17 o 1:195 18' 1:12029' 45 10' 125 43. 5-53' H 1476 31 125 27-29' 9 1440 18 14' o 1:250 , 1:30410' 45 05' 126 00-35' I 1495 26.3 125 27. 3-31 P 1455 20 o 1:250 14' 45 03' 125 41-58. 5' 1503 24 o 1:405 8.5' 1:24014,5' 45 56.2' 125 41-53' K 1520 18 125 23. 7-30' 0 1492 26 o 1:225 15' 44 51.2' 125 43-58' L 1538 20 o o 1:450 8' 44 45' 125 43-56' 1552 17 1:321 11' 1:30310' 44 41.2' 125 49.2-58' 1564 24 440395, 125°49-59' N 1564 24 125° 18. 5-26' M 1544 12

Average for entire channel length 1:2 17 2O Average for entire channel length 1:17923'

* t,-J A depths in fathoms -1 fan.The most distinguishing feature of the lower fan is the flat to slightly, concave surface with only a maximum of five fathoms of relief (Figure 6).All lower fan slopes have a gradient less than 1:400 and at the edge of the fan they may become less than abyssal plain gradients o1:1000.Normal slopes in this regionare 1:500 to

1:700.Again,, as in themiddle fan, the channels have a steeper gradient (1:300) than the fan surface (Table 2).

Channel Systems of Astoria Fan

Fan Apex

The deep fan valleys cutting the region of Astoria Canyon mouth make it difficult to designate any particular topographic high as the fan apex.Hurley(1960) called the elevated area just north of the canyon mouth the apex of the fan (Figure 7).The detailed bathymetric work of this study. and byCarison (1967) indicates that the topographic high probably is a portion of the continental slope.The other raised areas between channels may be original slope remnants, old fan remnantsleft between later channels,interchannel4 deposits, or some combination of these.Discussion of interchannel regions of the fan apex must be deferred until all lithologic and stratigraphic evidence hasbeen presented.Nevertheless, the immediate region

4lnterchannelrefersto fan regions between channels or fan valleys. 29

D-lOPiston Core ad Phieger Coresample station. Contour Interval: 50 fathoms (1000-1100) 10 fathoms (1100+) Contours based on 0.SLJ. Oceanography

Department soundings1 1965.

Compiled by Hans Nelson ,P

4615' I.--5 10 NAUTICAL MILES

o 10 KILOMETERS

A...Ancient Fan Valley

4600' yON

450451

F-3

I 26 125°45' 12530'

Figure 7. Physiography of the apex region of Astoria Fan. 30 of the canyon mouth, can be defined and discussed as the general fan apex. The two main fan valleys in the apex region seem to diverge from the mouth of Astoria Canyon.Astoria Channel can be traced continuously into the canyon mouth in cross-section profiles (Figure 4, A-D).However, on the basis of an increase in floor width, a decreasein width across the edge of the walls, and adevelopment of levees the region beyond 1140 fathoms is defined as the beginning of Astoria Channel and the end of Astoria Canyon (Carlson, 1967). The second major channel, the Slope Base Fan Valley, can be traced to a narrow valley between the continental slope and the Astoria Channel levee (Figure 4, A).Unfortunately, PDR track lines are not available to follow this narrow valley positively into the canyon mouth.Sedimentary evidence to be discussed later provides additional documentation that the Slope Base Fan Valley, does connect with themouth of Astoria Canyon. Other channels of the fan apex that do not connect with the present Astoria Canyon or Channel gradients (Figure 7, A-E; Table 3) appear to be remnants of old fanvalley systems. Thetwo northernmost of these(Figure 7, A and B) appear to lead into tributary valleys high on the north wall of Astoria Canyon.The three more southerly fan valleys (Figure 7,C,. D, and E) converge toward the position where Astoria Channel presently leaves Astoria Canyon. Table 3.Dimensions of Main Fan Valleys (to 1250 fathoms) of the Astoria Fan Apex (modified after Carison,1967)

Length Axial Axial Axial width (naut. relief depth (naut. miles) (fms) (fms) miles) Gradient

A 16 390 800 1 1024t

B 17 390 900 1 1°18'

C 6.7 125 110 2 1°03'

D 6 100 1135 1.5 0°58t

E 4.5 100 1140 0.75 1°15' Astoria Channel 16.3 125 1175 2 O°26

Slope Base Fan Valley 11.9 110 1170 1 0 30

Refer to letters on Figure 7.

Axial depth nearest the mouth of the present Astoria Canyon. 32 Astoria Channel makes a sharp turn to the left after leaving the canyon mouth. Menard (1955) first reported this phenomenon of the uleft hook" in several major deep-sea channels of the Northeast Pacific.He since has found similar "left hook" channels in other parts of the northern hemisphere (Menard, Smith, and Pratt,1965). The "left hook" is attributed to coriolis force, which in the northern hemisphere tends to build up the levee on the right and consequently shifts channels toward the left (Menard, Smith, and Pratt,1965). The north to south series of fan valleys observed in the fan apex region may be a result of this process.Carison(1967)has shown that these valleys have a change from steeper gradients in the northernmost region to lower gradients in the southernmost area (Figure 7, A to E).The axial depth at the point nearest to the present mouth of Astoria Canyon also changes and gets successively deeper from channels A to E (Table 3).The truncation and axial depths of the northernmost valleys are highest above the present canyon mouth and these valley gradients have the least adjustment to the present grade of fan valleys now connected to the canyon.All the data seem to indicate that the more northerly a valley is the older it may be.

Astoria Channel

Hurley (1960)stated that Astoria Channel is only a gentle 33 depression trending to the south.New data (Figures 3,4,5, and7) show that avery narrow and deep channel traverses the upper half of the fan and that the average gradient is 1:125.The levee crests range from 100 fathoms above the channel bottom at the mouth to less than 20 fathoms above the channel floor at the lower extremity of the fan (Table 2).The narrowing of the channel from three to four to two miles in the first 15 miles and the widened region where the channel turns south may be artifacts due to poor sounding control (Figure 7).

Beyond4501020t theupper Astoria Channel disintegrates into many distributaries and appears to shift easterly and form a wide, shallow trough extending to the south (Figure 3),The distributary development and shift of the northern, narrow channel result in a southern channel path that is much broader, shallower, and lower in gradient than the northern half of Astoria Channel (Figure 3, Table 2).

Slope Base Fan Valley

The Slope Base Fan Valley is more variable in character than is Astoria Channel (Figures 3 and 4).At its origin the Slope Base Fan Valley appears to be restricted to a mile wide area between the levee of Astoria Channel and the continental slope (Figure 4, A). For the next 20 miles to the south,it broadens to four to five miles. Near 450 10' to 450 20' N latitude the Slope Base 'Fan Valley breaks 34 into distributaries of less than a mile in width and with a greatly reduced gradient (Figure 4, T and S). The Slope Base Fan Valley gradients, channel depth, and width differmarkedly on the southern half of the fan (Figures 3 and 4, Table 2).The PDR traces seem to indicate that in the middle fan the distributaries from the northern Slope Base Fan Valley s1ift to the west away from the continental slope and converge into Astoria Channel (Figures 3 and 5).In this region between 45°20' and 4515' immediately off the slope, the SlopeBaseFanValley has a new gradient at a higher topographic level (Figure 4, R-P; Table 2). This new or elevated southern part of the Slope Base Fan Valley continues asa distinct feature at the base of the slope.Similar to the northern Slope BaseFanValley, it also tends to broaden and shift away from the immediate slope base toward the south.

Other Fan Valleys

Other fan valley systems can be identified on the fan (Figures 5 and 6).Often these channels appear as a series of notches in smooth topography (Figure 6).Some channels appear to connect and extend nearly across the fan; others appear to be discontinuous fragments.Because of insufficient sounding data, it is often impossible to tell whether channel fragments are partially buried portions of old systems or whether they connect as complete fan valley 35 systems.The abundance of channels may be explained by the tendency of fan valley systems to divide into many distributaries on the middle and lower fan and to shift leftward throughout history of the fan(Table 34.

Summary of Fan Valley Characteristics

The fan valleys tend to havea distinct, narrow, and non-braided nature in the upper fan.Fan valley gradients of theupper fan are steeper than channel gradients on the middle and lower fan, but are less than gradients of the interchannel surface.In the middle an4 lower fans, fan valleys begin breaking up into distributaries.Fan valleys in the middle and lower fan become broader, shallower, and lower in gradient than on the upper fan, but the channel gradients are steeper than the gradients of the interchannel surface.

Formation of Distributary Channels

Splitting of fan valleys into distributaries occurs on the middle fan where there is the sharpest change in gradient (Figure 6).Rapid change in gradient and distributary development in mid-fan seems to be typical for other deep-sea and alluvial fans (Menard, Smith, and Pratt, 1965; Bull, 1964). On Astoria Fan, sh.iftsin the position of the Slope Base Fan Valley, Astoria Channel, and basal margin of the continental slope suggest that tectonic activity may have affected 36 gradients in the middle fan region where distributary development begins. A combination of the changed elevation and gradient of the Slope Base Fan Valley in this same area also IndIcates that structural activitymay have disrupted the channel.Tectonic activityap- pears to have affected distributary development on Astoria Fan,but it does not provide a general explanation for gradient change and distributary development on any fan.Also,, if this change in middle fan gradient isabasic development in any fan, the formation of asingle major Astoria Channel at the lower edge of Astoria fan is puzzling; however, it maybe a fragment of an ancient channel not yet buried by later sedimentation.It. is apparent thatwith the present data, the basic cause of the abrupt change of gradient in the middle of fans cannot be explained.

Comparison of Astoria Fan Valleys with Astoria Canyon, and Cascadia Channel

Axial slopes of 1-3° in the upper canyon (Carlson, 1967) are much steeper than the axial slopes of Astoria Channel (Table 2).In the lower canyon the slopes generally are less than 1° and diminish graduallytoward those found inupper Astoria Channel.The canyon is narrow and has a V-shaped profile.The channel has a U-shaped, broad, flat valley.The channel walls rise more steeply above the valley floor, but do not have the relief of the canyon walls.The 37 levees alongside Astoria Channel also distinguish it from the canyon. Cascadia Channel differs markedly from the fan valleys of Astoria Fan.It fits Shepard's (1965) category of "deep-seachannels.H There is a continual 1:1000 gradient over a great distance in Cas- cadia Channel (McManus, 1964b),This contrasts with the variable and steeper gradients, and shorter lengths of the valleys on Astoria Fan (Table 2).Cascadia Channel is narrow, is deep, transects other major structural features such as Blanco Fracture Zone (Figure 1) and does not divide into distributaries.It appears to have rock walls in places.Magnetic anomalies align with Cascadia Channel (Raff and Mason, 1961).From these data it appears that Cascàdia Channel may lie along a structural feature as opposed to the erosional and depositional nature of the fan valleys.Thesis data of Duncan (1967) substantiates this interpretation.

Comparison of Astoria Fan Valleys with Other Fan Valleys

Astoria Fan valleys differ in some respects from those of other deepsea fans.Bates etal. (1959) concluded that fans normally feature a single, deep channel on the upper fan.Astoria Channel is the largest and most continuous fan valley, but a second definitive channel, the Slope Base Fan Valley, appears to diverge from the mouth of Astoria Canyon. Other remnants of channels exist on the upper fan. Levees of Astoria Channel, some of which rise over 65 fathoms above the general terrain also appear to be unusual (Figure 4, A). This is double the maximum height that Buffington (1952) gave in a study of levees.However, Shepard (1966) reported mid-fan levees with over 55 fathoms of relief along Monterey Channel. Menard (1955) proposed that levees should theoretically be higher on the right side.The right levees of Astoria Channel in general are only slightly higher and in some cases are definitely lower than those on the left. The number of distributary channels is much higher than the number noted on most fans (Figure 5; Table 4).Both Hurley. (1960) and McManus (1964b) mentioned the ??crenulations?I of Astoria Fan. With the additional sounding, data of this study, these crenulations appear to be numerous distributaries. that connect with fan valleys or channel fragments. More recent and detailed studies on other fans show increased numbers of channels (Menard, 1965; Wilde, 1965) and indicate that fan valley systems change with time (Moore, 1965; Shepard, 1966).Periodic formation of new channels appears to be the rule for deep-sea fans and may, account for the high quantity of fan valleys that are present.Menard, Smith and Pratt (1965) postulated that overflowing of the levees in two channel systems causes the development of a new channel in the inter-levee'area.This might be an explanation for the formation of the broad Astoria Channel trough on. the middle and lower fan.Sedimentary evidence cited later 39 substantiates this hypothesis. Recent, detailed studies of other fans show the similarity of gradients for various channels and fans.Shepard (1966) reported in- clinations of 1:90, 1:260, and 1:333 for the upper, middle, and lower segments of Monterey Channel on Monterey Fan.Slopes in the same segments of Astoria Channel are about 1:100, 1:200, and 1:300. On Monterey Fan, Wilde (1965) reported that gradients change from 1:125 to> 1:500 from the upper to the lower margins o the fan.For the Rhone Fan Menard described slopes from 1:100tol:1000,The gradients from upper to lower Astoria Fan generally range from 1:50 to 1:700.

Comparison of Astoria Fan with Other Deep-Sea Fans

Astoria Fan has the major characteristics that Bates, Mooney and Bershad (1959) listed for deep-sea fans (Table 4).These common features include fan channel gradients lower than associated canyon gradients, levees along the flanks of a main deep channel in the upper fan, and distributary channels of much lower relief on the lower fan.Astoria Fan is most similar in size to the Hudson Fan. The slope, length and width, total relief and intra-fan relief also are comparable for Astoria and Hudson Fans (Table 4). Bates, Mooney and Bershad (1959) found that fans usually have Table 4.Dimensions of Representative Submarine Fans of the World (modified after Bates et al., 1959) Apparent Associated Location Nautical miles Intra-f an Depth(fins) Number of Canyon NameLatitude Longjude Length Width Gradient relief Apex Base LeveesDistributaries

Mississippi 27°30 N 89° W 120 80 1:120 400f. 700 1600 yes 7

Hudson 37°N 70°W 80 80', 1:225 200 2100 2600 4

Congo 6°S 8°E. 150 100 1:227 115 1400 2100 yes 7

Rhone 42° N 4°30 E 90 90 1:90 250 400 1200 yes 11 **

Monterey 36°N 123° N 64 62 1:100* 250 1700 2100 yes 7

Coronodo 32° 30 N 117°22 W 5 4 1:100 35 675 760 3

Santa Cruz 33°47 N 119°45 W 4 5 1:60 25 950 1070 2

Hueneme 33°57 N 119°16 W 5 5 1:70 30 350 450 yes 3 33055 Redondo N 118°30 W 4 6 1:48 65 300 415 2

Trinidad 41°05 N 125°03 W 7 9 1:140 40 1360 1660 2

32°20 N 134°50 E 11 13 1:40 125 2400 2625 3

34°24 N 138°21 E 4 3 1:17 140 1400 1500 2

Astoria 45°53 N 125°30 W 90 55 1:200 150 1100 1550 yes 40

* Wilde (1965) states 1:250 overall average for Monterey Fan. Menard (1965) shows 15-20 on recent charts. 0 41 a 1:1 length to width ratio (Table 4).McManus(1964)noted that both Astoria Fan and Nitinat Fan are asymmetrical in shape.Drawings indicate that Monterey Fan is asymmetrical. (Menard,1960, p. 1272), although Bates, Mooney and Bar shad (Table 4) listed it with a 1:1 ratio.Delgada Fan is definitely asymmetrical in shape (Menard,

1960). When more detailed studies of fans are completed, it may be shown that many are asymmetrical but that depending upon where measurements are made they have a. 1:1 length to width ratio.

Menard(1960)mentioned that the boundaries of Delgada and Monterey Fans are controlled by the Mendicino and Murray fracture zones.Cascadia Channel with its apparent structural control may be a similar factor in determining the asymmetry of Astoria Fan. An additional possible factor contributing to the asymmetry of Astoria Fan is the shift of fan valley systems to the left and consequent net transport of materials southward. Another apparent difference in the physiographic interpretation of this study is that Astoria Fan seems to have three physiographic divisions.Previous investigators (McManus,1964)have separated Astoria Fan and other fans into upper and lower parts.The most prominent break in slope on Astoria Fan is at the base of the upper portion.However, the profiles (Figure6)and the bathymetric chart (Figures 3 and 5) seem to indicate three physiographic divisions on the basis of gradient change and slope convexity or concavity. 42 Alluvial fans also typically, show a three part division of fan head, mid-fan, and base (Blissenbach,1954;Bull,1964). More detailed analysis of bathyn-ietry may reveal this three part division for other deep-sea fans.Menard(1960)in a more recent survey was able to identify an apparent lower flank of Monterey Fan.

Heezen, Tharp, and Ewing(1959)noted that the continental rise has a significant break in gradient with the abyssal plains in the

Atlantic.Shepard(1963)and Hurley (1960) remarked that this does not seem to be apparent in the deep-sea floor of the Pacific.Astoria Fan is similar to the other regions of the Pacific in that the lower flanks of the fan grade imperceptibly into the 1:1000abyssal plain gradients(Figure6). The abundance of deep-sea fans off the west coast of North America and the general lack of them off the East Coast may explain this difference in gradient transition in these two continental rise regions.The fan depositional process on the Pacific continental rise generally transports an& deposits materials latera1ly away from the continent.This would tend to smooth gradients between the deep-sea floor and the continental margin.Heezen, Hollister, and Ruddiman

(1966)believe that geostrophic contour currents parallel to the continental margin deposit the sediments on the East Coast continental rise.This type of depositional process would tend to preserve gradient changes between the lower continental margin and the deep-seafloor.It is, interesting to note that both processes result in continental rise gradients that are nearly the same.

Astoria Fan Compared with Alluvial Fans

Many similarities exist between the physiography of alluvial fans and deep- sea' fans.The general shape of the profile of both is concave.Three physiographic gradient rings are developed from the apex to the lower, margin in each. kind of fan.Sharp, pronounced channels in the upper part break into distributaries. in the lower part of both types of fans (Blissenbach, 1954; Bull, 1964). Astoria.Fan and other deep-sea fans differ from alluvial fans on land in being much larger and flatter.Blissenbach listed gradients of 10_90 in fan heads of alluvial plains (upper fans), and gradients usually of about10in the lower fan.Astoria Fan has gradients of 30' at a maximum; this is characteristic of most deep- sea fans (Table 4).Bull (1964) noted that Panoche Creek Fan, the largest (670 sq km) of 20 alluvial fans in Fresno county, has upper fan to lower fan slopes of 18'-08'.AlthoughPanoche Creek is the largest fan, in Fresno county, Blissenbach reported that Grabeau listed an alluvial fan with a radius of 65 km.The average radius of Astoria Fan is 140 km and this is not large for a.deep-sea fan (Table 4). Eckis (1928) noted that the larger the drainage area, the lower are the stream gradients for alluviaL fans. Laboratory studies on alluvial fans by Hooke (1966) showed that the higher the discharge and the finer the sediments, the lower will be the fan gradients.In deep-sea fans the larger the sediment source is, the larger the fan is, and the lower the fan gradients are (Table 4).Deep-sea fans generally are larger, have lower gradients, and derive finer sediments from higher discharge rivers with larger drainagebasinsthan do alluvial fans (Figure 1). 45

V.SEDIMENTS

Sampling. Methods

Forty piston cores up to 600 cm and averaging 409 cm in length, and 40 Phleger trigger weight cores up to 60 cm and averaging 38 cm in length were collected from Astoria Fan (Figure 2; Appendix 1). From these cores 350 samples were analyzed for texture and for coarse fractioncomposition5(Appendices 2 and 3).Light minerals, heavy.minerals., refractive index of ash, and displaced benthonic foraminifera were analyzed for 20 to 30 samples.The methods of analyses are outlined in Appendix 4. Extreme carewas necessary in selecting the samples,. particularly at the top or bottom of cores, because of anomalies pro- duced during the piston coring process. A description of these anomalies and their effects on.stratigraphy are given in Appendix 4. Sampling was concentrated on coarse layers because of their abundance and significance for sedimentary processes.The coarse layers in Astoria Fan are intermittent beds more than one cm thick with a mean grain size of medium silt or coarser.Wherever possible, samples were taken from the clay below a coarse layer (Figure 8F, a), the graded coarse layer(Figure 8F, b), and the clayey. silt tail above

5Materialgreater than 62 microns in size. Figure 8.Sediment types of Astoria Fan.

A. brown clay over olive gray clay, from lower Astoria Fan- core 6509-16; B.olive gray clay with burrow mottling, from lower Astoria Channel- core 6509-4; C. gray clayey silt with silty organic laminae, from levee of the middle fan portion of the Slope Base Fan Valley - core F-4;

D. gray clayey silt with silt laminae, from levee of upper Astoria Channel - core E-3; E.gray silty clay with pebbles, from wall of upper Astoria Channel - core D-Z (note depression of lamina beneath rafted pebble); F.tuffaceous, gravelly, woody coarse layer in olive gray clay, from upper Astoria Channel - core D-10;

0.lower fan graded coarse layer (b) in gray silty clay (c) with a clayey- silt tail (d)- core 6509-7;

H. tuffaceous layer (a) and gravel layer (b) in olive gray clay of the upper Slope Base Fan Valley - core F-3. Note: For core location see Figures 2 and 6, and for total core lithology see Figure 10. - 130

_____ \ DEPTh \ IN - )CORE 7,T

/10 r - - 140 B D V..:

A C -.

'fl 25 270 -

Burrow

30 285

-a OLIVE GRAY CLAY CLAYEY SILT PEBBLE CLAY COARSE LAYERS the coarse layer (Figure 8F, c).Where these coarse layer sequences were available throughout the core, they were sampled at even intervals.Where the sequences were 1acking, samples were taken at important lithologic breaks and at intervals in clay and coarse layers.

General Stratigraphy of the Fan

Olive gray clay, that has interspersed silt to gravel horizons, makes up the upper sediment unit and all the material foundin Phieger cores (Figure 8A).Beneath the olive gray clay section is a thinly laminated to thick-bedded gray silty clay.This was penetrated to the maximum piston core lengths of 610 cm (Figure8 C, D, E, G; Appendix 5,B-4). Olive gray clay constitutes the upper stratigraphic unit over the entire fan.It occurs immediately beneath one to four cm of brown oxidized surface clay on the lower and middle fan, and at the surface on the upper fan and near the continental slope (Figure 9).In places the olive gray clay is interbedded with coarse grained layers, some of which are ash-rich (Figure8H-a).Commonly this clay is mottled by worm burrows (Figure8B). The olive gray clay is about one meter thick in the interchannel regions.The actual variance in thickness in the cores is about 50.- 150 cm, but coring anornaliesmay produce these differentials (Ap- pendix 5).For example, some piston cores had no olive gray clay, 49

Figure 9.Thickness of Brown Clay (shown by intensity of shading) and of Olive Gray Clay (shown by number of core location).Star indicates that core did not penetrate to Pleistocene gray silty clay or coring anomaly caused a loss of or stretching of part of the Olive Gray Clay section. but the corresponding Phieger core contained over 50 cm depth of olive gray clay (Appendix5, B-4).In the main channels (Cascadia Channel, Astoria Channel, and the Slope Base Fan Valley) only olive gray clay was present to the maximum cored depths of five meters (Figure 10, coreS D-10, 6509-4, A-4A; Appendix 5). Gray silty clay, the lower stratigraphic unit found throughout the fan, is interbedded with numerous sand and silt layers.These coarse layers range from silt and organic laminae less than amilli- meter thick to sand layers over 40 cm thick.Coarse layers over about two cm thick have sharp contacts with the underlying. clays and usually grade evenly into clay, at the top of the layer. Within stratigraphic units there is regional variation, and the greatest diversity occurs n the upper fan.Gray. silty clay of the upper fan contains numerous,organic. 'and 'clastic fine silt laminae (Figure 10, cores A-2, F-2; Figure 8, C-E) it contains numerous coarse layers in the middle and lower fan. (Figure 10, cores D-3, B-4).The floors of themain channels in the upper fan consist. of silt, sand, and gravel layers in.a thick section of olive gray clay (Figure 8, F, H; Figure 10, core D-10).In the middle and lower fan the main channels contain no gravel layers and the coarse layers have finer grain size (Figure 10, cores 6509-4, 6509-5).The walls of upper Astoria Channel are covered by less than a meter of olive gray clay which is. underlain by gray silty clays with isolated large 51 UPPLRFA N CORES MIDDLEFAN LOWERFAN CORES ChwaII Oh Ic Oh Lv iS Ic IC 'Oh Ch Ic Iv icS' D-2 D-1O A-2 F-3 E-3 D-3 A-32 E-4 65-5A-4A65-465-7 5515[3-6 65-i 0 ON

H C- C-

9, CS -' 100- 'a C--

- '9 '9 '9 '9 £

'9 '5 .9 '9 - C-

.9 9

95 '9 " 'S 200 9, '9 'a

'9 C- '9 59

9, = C- -- 'a

'9 SILlLAMINAE

300- - '' COARSE LAYERS '5 - 59 -- 8 ASH RICH LAYERS

- 'a PEBBLE

'a RADIOLARIA RICH 'a OLIVE GRAY CLAY 59 59 FORAM RICH GRAY

400- SILTY CLAY

500

Figure 10.Representative lithology of Astoria Fan arranged in order of increasing distance from fan apex at the left.Identifiable coaree layers, ash rich coarse layers, and stratigraphy are marked. For geographic location of coarse layers see Figure 2, and for profile location of cores see Figure 6.Note the irreased uuniber of coarse layers in channels, on the middle and lower fan, and at depth in the cores. (Physlographic location: CH = chani1, Icinterchannel, Lv * levee, 65- 4core number 6S09-4) 52 pebbles: (Figure 10, core D-2, Figure 8E).Gray silty clay with pebbles was not encountered onthe middleand lower fan.Beneath a meter of olive gray clay the levees of the main channels consistof gray silty clay with numerous silt and organic laminae(Figure10, core E-3; Figure 8C, D).

Lithology, Texture, and Coarse Fraction of Sediment Types

General

On the basis of texture, coarse fraction, and lithology, the sediment types are divided into the following categories: brown clay, olive gray clay, gray silty clay, gray silty clay with pebbles, ciayey silt, and.coarselayers of sand and silt.Each of these sediment types has associated textural and compositional parameters that are a product of the sediment source, depositional processes, andsedi- mentation history.By delineating these sediment parameters and their physiographic distribution, sedimentary processes and stratigraphy can be determined.Tracing the history of individual sedimentation events and of long term stratigraphic changes increases knowledge of geologic processes and history. In Tables 5 and 6 the limits and modes (includes> 50 percent of the samples) of grain size, mean diameter, skewness, sand-silt- clay percentages, and coarse fraction composition are summarized

* Table 6. Summary of Coarse FractionCharacteristicsof Fan Sediment Types Sediment Physiographic Biogenous Platyterrigenous T errigenous ype location Max. Mm. Mode Max. Mm. Mode Max. Mm, Mode

Clay All samples 95 22 50-95 78 4 5-50 58 <1 <1-20 All olive-gray 94 25 50-95 63 4 5-25 58 <1 <1-20 All gray 95 22 40-90 78 5 10-60 47 <1 <1-15

Clay Upper fan 78 25 50-75 45 14 15-40 58 <1 <1-15 Olive-gray Middle fan 90 33 50-90 63 5 10-40 39 <1 <1-15 Lower fan 94 35 70-92 58 4 5-25 46 <1 <1-10

Clay Upper fan 74 22 20-60 78 9 15-80 48 <1 <1-20 Gray silty Middle fan 95 40 75-95 48 5 5-16 11 <1 <1-15 Lower fan 90 35 48-78 49 7 9-49 38 1 <1-10

Pebble Upper fan 0 0 -- 40 6 6-30 94 60 70-90 Clay-

Clayey silts All samples 35 0 0-20 99 10- 75-100 85 0 Upper fan 24 0 0-15 95 27 75-95 68 0 3-20 Middle fan 20 0 0-18 99 20 80-100 79 0 0-25 ** 35 99 10 85 2 Lower fan 0 ) 0-10 MI J 25-50 MI 10-75 20-35 75-100

Coarse All samples 10 0 0-3 99 <1 0-30 100 2 60-100 layers Upper fan 8 0 0-5 45 1 1-45 98 48 63-98 Middle fan 5 0 0-2 99 <1 1-40 100 2 60-100 Lower fan 10 0 0-2 80 <1 1-30 100 21 70-100

* %by relative#of total fraction >62. ** Two modes present, Ml=most important mode. u-I Gray silty clay with pebbles. 55 according to sediment type and physiographic province.In Figures 1l.15 certain parameters of texture and coarse fraction are com pared with physiographic and stratigraphic sample locations so that Astoria Fan sediment types may be defined, To make meaningful comparisons,, the coarse fraction consti tuents need to be organized into major categories.The constituents of the coarse fraction can be divided into three major groups de pending upon their genesis (Appendix 3):detrital, authigenic, or biologic materials.Division and explanation of the minor groupings are given in Appendix 4.The detrital materials consist of light colored minerals (mainly quartz and feldspar), dark colored mm- erals (mainly ferromagnesian minerals), platy minerals (mainly micas), rock fragments, volcanic glass shards, and yellow frag ments (mainly weathered grains; Ru.nge, 1966).The authigenic materials are glauconite and pyrLte.The biologic materials include planktonic and benthic foraminjfera, diatoms, radiolarians, plant fragments, pollen,arid other biologic remains such as. spicules, echinoid spines, and megascopic shell fragments. The sediment types are characterized by coarse fraction materials grouped by depositional processes, not genetic origin. Therefore, three I!process groups are distinguished.The first of these isterrigenous' materials deposited by relatively, strong currents.This coarse fraction group contains land-derived debris 56

4O A UPPER FAN COARSELAYERS

3,5

, 3O- MIDDLE AND LOWER . FAN COARSELAYERSN N 25L \ I 4.j p 2O-\ / )1,P., / p / p p 15- è p_-v 4.'P p . p p p pp P Pp -e- I.O l, b 1 . . p p p p U

I- 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0 5.O UPPER FAN COARSE LAYERS 45 )

Q. 4.O pP S

3.5 p MIDDLE AND LOWER \\ FAN COARSE LAYERS (, 51 2 5- 0) P p 2.O P .* pp

p P

IO I(

5F Pd.1,P . . _1,_ ------2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0 6.5 Ph MEAN DIAMETER(M4) Figure 11.Relation between sorting versus mean grain size, physiographic location,and coarse fraction content of Astoria Fan coarse layers.Based on statistical parameters of (A) Folk and Ward (1957) and (B) Inman (1952). (Below dashed lineare middle and lower fan coarse layers; above dashed line are upper fan coarse layers.) 4.O CLAYEY SILTS 0 35- 0 9 0 9 3.0 1, t: 0 0,99 25 O 0 00 9 2.0- 0

4 LO 0 0 9 5

I 5.5 6.0 6.5 7.0 7.5 8.0 8.5 9.0 9.5

3-5r GRAY SILTY CLAYS Coarse Fraction Content in Sample U 3.0 TerrigeflOUS b z 2.5 0 Platy Terrigenous c1

I- o 2.0- Biogenous > LU 8 9 0 Fan Sample 6 )5 OLIVE GRAY CLAY Upper Middle 9 Lower

1.5

10 NotePebble Clay 4.O[ Gray Silty Clay with Pebbles. ) PEBBLECLAYS

3.5H B

8 9 Phi MEAN DIAMETER (M') Figure 12.Relation between sorting versus mean grain size, physiographic location, andcoarse fraction content of fine-size sediments of Astoria Fan. Basedon statistical parameters of Inman (1952). .8 UPPER FAN COARSE LAYERS,(AAAA / 7 / A Al A A

6 A A A A A A 5 A A A A A\AJ A A A A A A A A A A A A AA A A .3A A AM A AA A A AAA AA A .2 A A A A AAA A A A A AtA A .1 A A A A A A A A 0 A AA AA A A -.1 A MIDDLE AND LOWER A A FAN COARSE LAYERS

A A 3L U, -4 25 3.0 3.5 4.0 4.5 5.0 5.5 6.0

Vi)

5L S CLAYEY SILTS

4L. . GRAY SILTY CLAY I 3L O/oS o .o.00u 2H . 0 S 0 oh

GRAY SILTY CLAY/PEBBLES OLIVE GRAY CLAY

- 6.0 6.5 7.0 7.5 8.0 8.5 90 9.5 0 Phi Mean Diameter (M') Lithologic Type Stratigraphic Unit i Coarse Layer OClayey Silt Gray Silty Clay oClay Layer 0 Olive Gray Clay Figure 13.Relation between skewness versus mean grain size and stratigraphic units of Astoria Fan sediment types (Inman, 1952). 59 CLAY

Coarse Layer /T. Clayey Silt DGray Silty Clay / /UPPER\ Gray Silty Clay with Pc b b I e s Olive Gray Clay

SILT A CLAY

/t 75 //// S MIDDLE 20FAN

- SAND SILT A CLAY

5/ // LOWER FAN J 20

SAND SILT

Figure 14.Sand-silt-clay content o sediment types in the various physiographic regions of Astoria Fan. BIOGENOUS

LI \

LI FAN/

./ 4 / I

. S TERRIGENOUS PLATY TERRIGENOUS ( BIOGENOUS COARSE LAYER CLAYEY SILT /// '/ CLAY LAYER / PEBBLE CLAY GRAY SILTY CLAY // OLIVEGRAYCLAY/ Figure 15. / // LILI Terrigenous, platy-terrigenow, / and biogenous content ofsedi- LI ment types in the various physio- MIDDLE FAN \ ./ graphic regions of AstoriaFan. \\ / S

/ \ / \LII o.

-'--.!-- TERRIGENOUS PLATY TERRIGENOUS I BIOGENOUS // LI /LI LI\ / LI LI / / Ne: Pebble Clay = Gray Silty Clay with Pebbles. / LI ----/,LI LOWER FAN / .

. ,// : \\ // \ 5 / N LI LI \ / $LI

TERRIGENOUS PLATY TERRIGENOUS 61 of quartz-feldspar, heavy minerals, rock fragments, and yellow grains. A second major coarse fraction group of terrigenousmaterials includes detrital mica, terrigenous plant fragments, and pyroclastic and epiclastic volcanic glass.The piaty shape of these constituents makes them particularly sensitive to even very low currents that will sort out and transport them.Since these materials are carried from sediment sources of the continental margin, this coarse fraction group is called "piaty-terrigenousmaterials.The third coarse fraction group,biogenous remainsYismainly. ma1e up of pelagic biological contents, but includesail the materials formed by life processes within the ocean.Plant fragments and pollen of terrigenous origin from plants at or along the seashore are not included.The autocthonous 'biogenous remains are deposited mainly with clays from continuous particle by particle sedimentation.

Brown Clay

Brown clay (Figure 8A;GSA Rock Color Chart lOYR-Z/2) appears to be olive gray clay which has oxidized at the sediment water interface.The two clays seem to be of the same lithologic unit because they have nearly identical characteristics of texture and corn- position (Appendices 2,3; samples 409, 409a, 437, 437a; Figure 16). The brown color alteration does not occur at depth in the olive gray clay or near the base of the continental slope.This may, be explained i 25 125 .083 .031 .016 .008 .004 .002 .001 mm.

! 40

8 JU JI IlPbI -2 -1 0 1 2 3 4 5 6 7

Figure 16.Representative cumulative size frequency curves forAstoria Fan sediment types. 63 by lack of oxidizing conditions or more rapid deposition near the slope.Only. a slight development of one to two cm of poorly consoli dated and gelatinous brown clay is found in the middle fan, but four to five cm are found on the lower fan (Figure 9; Appendix 5).Pos sibly, slower deposition rates at greater distances from the continent allow oxidation to greater depth.

Olive Gray Clap

Olive gray clay generally has few silt or organic laminae but is sparsely interbedded with clayey silt layers and coarse layers (Figure 8A, B; GSA Rock Color Chart SY-3/2).Mottled clay and many fecal pellets indicate much b e n t h i c activity that probably destroyed any fine laminations of organic and silt. sized material (Figure 8B).The olive gray clay, like the brown clay, is poorly consolidated, watery, and lacks cohesiveness compared to the gray clay. Olive gray clay. is amedium..coarse size clay (Wentworth, 1922; Table 5).Its mean size limits are the most restricted of the clays (8. 8 to 9. 8 c), with the finest mean size limits and modes occurring on the lower fan.The uniformity of the olive gray clay is shown by the ranges of sand, silt, and clay percentages, which are much more restricted than for any other type of clay.Olive gray clay ranges from clay to silty clay in terms of sand, silt, and clay composition (Figure 14; Shepard, 1954) and has the highest content of clay of any of the clay lithologies.Olive gray clay has its highest clay content on the lower fan at the greatest distance from the continental slope (70-80 percent; Figure 14).As a result the lower fan clay has the lowest silt: clay ratios (about 0. 2), of any sediment on the fan. Olive gray clay is a poorly to very poorly sorted sediment but has a more limited range of sorting and is better sorted than other clays (Figures 12 and 16),The limits of sorting become larger down the fan, but modes show that sorting becomes better in the lower fan.Olive gray clay ranges from slightly positively to negatively skewed (0. 1 to -0. 3), but the mode of the skewness is defi.. nitely negative (Figure 13).The lower fan has the most negatively skewed olive gray clays. Olive gray clay contains the highest content of biogenous constituents in the coarse fraction of any sediment on the fan (Figures 14 and 15).The coarse fraction of the olive gray clay always is over 25 percent biogenous (Table 6) and 90 percent of the samples have over 50 percent or more biogenous constituents in the coarse fraction.Radiolarians are the dominant biogenous constituent (Figure 10; Appendix 5).These never make up less than ii percent of the coarse fraction and in some places make up more than80 percent.In the olive gray clay, planktonic foraminifera make up 65 less than five percent of the coarse fraction. Away from the fan apex' and the continental slope, the per-. centage of biogenous constituents becomes higher.According to limits and modes of the samples, the highest quantity of biogenous material is found on the lower fan.In deeper olive gray, clays, some lower fan sediments contain a relatively high percentage of tern- genous constituents.This may be evidence that benthic organisms have mixed up the sediments or that biologic or sediment prcesses were d.ifferent during early deposition of the olive gray clay.

Gray, Silty Clay

Gray silty clay is definitely a grayer shade than olive gray clay, which overlies it.However, the actual moist colormeasure- ment for the gray silty clay is olive gray to light olive gray by the GSA Color Chart(5Y-4/l; cf. Figures 8B and8C).The gray silty clay is much better consolidated than the olive gray clay and lacks evidence of b enthic activity, which is so prominant in the latter. Mottling and fecal material are only rarely encountered and even the finest laminae are preserved. Gray clay typically 'is interbedded with coarse layers, silt laminae, and organic layers (Figures 8, C- E,G). Range of mean size of gray silty clay is from coarse to fine clay (8. 3 - 10. 04)and the range is greater and coarser 'than that of olive gray clay (Figure 1 2, Table 5).The higher quantity of silt and higher silt: clay ratios also show that gray silty clay is coarser than olive gray clay (Figure 14).The progressively finer modes of mean size, the lower percentage of sand and silt, and the higher percentage of clay indicate that gray clay becomes finer down the fan just as the olive gray clay does.

Gray silty clay is very poorly sorted (2 -2.. 5 ) and generally is positively skewed; both limits and modes indicate a poorer and wider range of sorting values and more positive skewness than for olive gray clay, (Figure 12, Table 5).The change in limits and modes of sorting values is neither gradual nor consistent over the fan as it is with the olive gray clay.Gray clay ranges from posi.- tively to slightly negatively skewed (-0. 1to 0. 3), but most of the gray silty clay is positively skewed and near zero (Figure13).The greatest variation in skewness values is found onthe lower fan for gray silty clay, as it is for the olive gray clay. Planktonic foraminifera are dominant in the coarse fraction of the gray silty clay whereas radiolarians are dominant in olive gray clay.Overall, the amount of biogenous material in gray silty, clay is less and is more variable than that in olive gray clay.All gray silty clay samples have more than 25 percent biogenous materialsand most have over 50 percent.The two clays are similar in that the biogenous constituents of the coarse fraction become moreabundant 67 on the lower fan.

Gray Silty Clay with Pebbles

Thick sections (> 6 m piston core length) of gray silty clay with occasional pebbles (one to four cm in diameter) occur in the walls and adjacent interchannel regions of Upper Astoria Channel (Figure 8E).The pebbles are mainly basalt, are rounded,. and occasionally are striated.The highest amount of sand and silt, and the lowest amount of clay of any of the clay lithologies are found in the pebble clay (Figure 14; Table 5).Pebble clay minus the pebbles has a mean size of coarse clay (Wentworth, 1922), and is coarser and more poorly, sorted than any other clay of the fan (Figure 12). The pebble clays are slightly positively to slightly negatively, skewed; the mode of skewness is negative. The coarse fraction composition of the gray silty pebble clay lacks the biogenous constituents common to the other clays.The terrigenous constituents comprose over 90 percent of the coarse fraction and the remainder is made up of platy-terrigenous. materials.

Clayey Silt.

Clayey silt is found in both the olive gray and the gray silty clay units; however, it i.s much more common in the latter.Clayey silt has several different lithologic forms.It.may occur as clay with visible silt or silty organic laminae up to several millimeters thick (Figure 8, C, D); it also may be found as silty clay or clayey- silt gradations into clay lithology above coarse layers and between closely spaced coarse layers (Figure 8G-a, 180-188 cm; 8F, 42- 48 cm).Because some clayey silts occur in the continuum from coarse layer to clay lithology, a few sediments that appear to have coarse layer or clay layer lithology actually have textural and coarse fraction parameters of clayey silts; occasionally, sediments that appear to be clayey silt by megascopic lithology actually have texture and coarse fraction of coarse layers or clay layers. Sand:silt:clay percentages of ciayey silts range from nearly all silt to 75 percent clay.Sediments of the clayey- silt type, therefore, are categorized according to the Shepard (1954) classification as silts, clayey silts, and silty clays.Collectively, as a sediment type, this make the clayey silts coarser than the clay lithologies and finer than the coarse layers.However, because coarse layers grade continuouslyinto clay, a few clayey-silt samples may have sand:silt: clay ratios similar to those of coarse layers or clays (Figure 14). A general coarsening of clayey silts down the fan is indicated by the increase in silt and the decrease in clay percentages.The resultant silt: clay ratios become increasingly larger with greater distance from the fan apex. The mean grain size of clayey silt ranges from coarse clay to medium silt (6 - 94));the mode occurs in the very fine silt class. Both the size limits and the modes indicate that the coarsest clayey silt occurs on the lower fan.In addition, the lower fan has the widest range of size limits and size modes. The clayey silts are moderately to very poorly sorted with the mode being very poorly sorted (Figure 12).The sediment sorting appears to be slightly better on the lower fan and here the best sorted sediments, coarse clayey, silts, are poorly sorted. The skewness of ciayey silt ranges from very positive to slightly negative, but the mode is positive.Both skewness limits and modes indicate a trend from less positively skewed clayey silts on the upper fan to more positively sicewed clayey- silts on the lower

fan. Composition of the coarse fraction of olive gray or gray clayey silt is similar for channel or interchannel regions.Nearly all clayey- silt sediments are low inbiogenous constituents (< 15 percent) and high in platy-terrigenous materials (>50 percent).Clayey silts usually contain well over 75 percent platy-terrigenous constituents and less than ten percent biogenous material in the coarse fraction. Coarse fractions of clayey- silts consist of a relatively high quantity of terrigenous or biogenous materials if mean size of the sediment is relatively large or small, respectively.One group of clayey-silt sediments on the lowerfancontains high quantitiesof terrigenous 7Q material and another contains a high amount of biogenous material (Figure 15).Thus, on the lower fan, three types of clayey silts can be distinguished by their relatively high contents of platy-terrigenous, terrigenous, or biogenous constituents compared with clayey silts on other parts of the fan.The gradients in texture and composition with distance down the fan help to explain the variance that is found in the clayey silts.

Coarse Layers

Coarse layers are present in olive gray and gray silty clay, and range from coarse silt to gravel layers.Sand-size sediments usually make up the basal portion of thick coarse layers (Figure 8G- b),ihile upper portions usually grade into silt to clayey- silt size (Figure 8G-a). Many of the coarse silt layers in the olive gray clays are ash-rich (Figure 8H-a, 33-36 cm).Some muddy, tffaceous sands (Figure 8F, 67-80 cm) from Astoria Channel near the mouth of Astoria Canyon contain pebble-size fragments of shell, wood, and pumice.The only layers with mean size of gravel occur in the upper Slope Base Fan Valley (Figure 8H-b, 43-50 cm). Coarse layers range from nearly pure sand to pure silt and may be classified as sands; clayey sands; silty sands; sand-silt-clay- sands; sandy silts; silts; and clayey silts (Shepard, 1954) (Figure 14). The sand, silt, and clay percentages show important changes down 71 the fan.The coarse layers of the upper fan contain a high quantity of clay and lack silt; the coarse layers of the lower and middle fan lack clay and usually have a high quantity of silt (Figure 14).Con.. sequently, very high silt:clay ratios are found in coarse layers of the lower fan while just the reverse is true in coarse layers of the upper fan. Except for the few gravel layers, the coarse layers have a mean size that varies from medium sand to medium silt (2 6), with the majority from fine sand to coarse silt (Figure 14),Other than the coarse sands and gravels of the upper channels, the coarsest layers are on the lower fan according to the limits and modes of mean size. As a group, coarse layers exhibit the best sorting of any sediment type on the fan.They range from well sorted to extremely poorly sorted, but generally are moderately to poorly sorted (< 2 ) (Figure 11).Coarse layers from the channels of the upper fan are the most poorly sorted sediments on the fan (Figure 1 1). Using Inman parameters, the majority of coarse layers are positively skewed (Figure 13), but skewness varies from very positive (+0. 6) to negative (-.0. 3) in sands and from positive to zero in coarse silts.According to the more sensitive (5th - 95th percentiles) statistical parameters of Folk and Ward (1957), all coarse layers are positively skewed.Channel coarse layers of the upper fan are much more positively skewed than are the middle and lower fan coarse layers. Two coarse layer samples with a mean size in the granule class (..l. 6 4and ..l. 75) occur at the top and bottom of a layer penetrated for 10 cm in the upper Slope Base Fan Valley (Appendix 2, 423 and 474; Figure 8H-b).The gravel layer contains 57 percent gravel, 35 percent sand, 6 percent silt, and 3 percent clay at the top; and 71 percent gravel, 22 percent sand, 4 percent silt, and 3 percent clay at the bottom,The sorting and skewness also are graded from 4. 5at the top to 2. 014at the bottom of the layer for the sorting, and from 0. 0 at the top to 0. 14 at the bottom of the layer for the skewness. The main constituents of the coarse layers are terrigenous materials which make up more of the coarse fraction as the mean size increases(Figure 11).Consequently, there is a trend toward a higher quantity of terrigeious constituents down the fan since the layers become coarser.Nearly all coarse layers have greater than 75 percent terrigenous constituents (Folk and Ward, 1957).Because glass shards are arbitrarily grouped with platy-terrigenous constituents, some tuffaceous coarse layers of silt size have a dominance of platy-terrigenous constituents.The biogenous content is the lowest of any sediment type, and usually is less than one percent of the coarse fraction. 7.3

Plots of Sedimentary Parameters and Sediment Types

Plots of textural and coarse fraction parameters, in addition to interrelationships of physiography, stratigraphy, and lithology, define the sediment types. of the fan.The general significance of the plots of sedimentary parameters should be reviewed before giving a synopsis of the sediment types.Both the mean vs. skewness diagram and the mean vs. sorting diagram have a general sinusoidal shape to the plot.The mean-sorting diagram shows a change to very poor sorting at about 6and returns to better sorting in the finest olive gray clays at 9 9. 5 . The sinusoidal shape of the mean vs. skewness diagram is caused by the lower skewness of the coarsest and finest sediments, whereas the coarse and clayey silt layers in- between generally have a very positive skewness.From. mean size

6 to 74the range of skewness. is the most limited of any sediment

(O.6toO.and gradually becomes lower. Variance of skewness occurs according to different physiographic regions.All upper fan samples down to clay, size, except for the pebble clays, are very positively skewed.Nearly, all middle fan samples are positively skewed, but generally have greater uniformity and a lower range of positive skewness than the upper fan sediments. As a group the sediments of the lower fan have the lowest skewness values because most of the coarsest and finest 74 sediments on the fan are found there. The sand:silt:clay diagrams also reveal regional differences (Figure 14).The upper fan has coarser clays than the middle and lower fan; its sediments generally are low in silt.As a result, the clayey silts of the upper fan may contain over 50 percent clay, whereas similar lithology in the middle and lower fanrnay contain over 75 percent silt.Only a few coarse layers are found in the upper fan outside the channels.These have a very low sand content. Coarse layers in the middle and lower fan are equally abundant in channel and interchannel regions and have similar amounts of sand, silt, and clay. As a rule, lower and middle fan coarse layers con- tamless clay than those in the upper fan (Figure 14).Coarse layers of the lower fan contain the highest percentage of silt-sized material and the lowest percentage of clay.Clay layers of the lower fan con- tamthe highest percentage of clay. The coarse fraction of each sediment type has a characteristic composition although some regional differences occur over the fan (Figure 15).With the exception of a few lower fan clayey silts, all of the coarse layers and clayey silts contain less than 15 percent biogenous constituents.The coarse fraction of nearly, all clay layers consists of more than 25 percent biogenous constituents.The coarse fractions of gray silty clays rarely are composed of over 75 pe.rcent biogenous constituents and the coarse fractions of olive gray clays 75 rarely contain less than 40 percent biogenous constituents.Nearly all clayey.. silt sediments contain more than 50 percent platy- terrigenous materials in the coarse fraction while coarse layers usually have over 75 percent terrigenous materials in the coarse fraction. The percentage of biogenous material increases down the fan in the olive gray clays; the increase is less in the gray. silty clays than in the olive gray clays.The platy-terrigenous constituents de. crease and the biogenous constituents increase in clayey silts down the fan.The content of platy-terrigenous and biogenous materials in coarse layers decreases from the upper fan to the lower fan.

Definition of Sediment Types

It is evident from the data that distinct sediment types can be identified by characteristics of texture, composition, lithology, and stratigraphy. Upper Fan CoarseLayers (15 samples).Coarse layers of the upper fan valleys constitutethis group.These fine sand to medium silts occur, in the thick olive gray clay section of the channels (Figure 9).These layersare characterized by extremely poor sorting, usually over 3. 04,byvery positive skewness, normally over 0. 3, and by high content of clay compared to other coarse layers (Figuresli, 13 and 14).This group contains sands, ciayey sands, iLl silty sands, and sand-silt-clays.The upper fan coarse layers are characterized by low silt:clay ratios similar to those of clay layers. The high clay content in these coarse layers and the low silt content, that is typical of the upper fan sediments, cause the low silt:clay ratio that is unusual for coarse sediments.The coarse fraction of this group contains over 50 percent terrigenous material. Middle andLower Fan Coarse Layer(101 samples).This group of sediments is composed almost entirely of coarse layers of the middle and lower fan.These coarse layers occur in both the olive gray and gray silty clay stratigraphic horizons and in channel and interchannel regions.They range from medium sand to medium silt and are classified as sands, silty sands, and sandy silts.Sedi- ments of this group have the highest silt:clay ratios and are the best

sorted of any. sediment type on the fan (sorting coefficient = < 2. 0). They are relatively coarse, have low clay content, positive skewness Folk andWard (1957)statistic, and a coarse fraction of 75 percent or more terrigenous materials (Figures 11, 13-15). Clayey Silt.The clayey- silts occur in all physiographic regions and in both the olive gray. and gray stratigraphic sections. They have mean size ranges between clay layers and coarse layers and consist of silts, clayey silts, and silty clays.The distinguishing characteristics of the clayey silts are the range of mean size

(6 to 8. 5), the sorting,. which generally, is over 2.0cj, and the 77 composition of the coarse fraction, which is over 50 percent platy- terrigenous constituents and less than 25 percent biogenous constituents (Figures 12,14,15). Gray Silty Clay (50 samples).The gray silty clay group occurs as clay layers of the gray silty clay stratigraphic horizon.They are characterized by very poor sorting coefficients (over 2. 0c)positive skewness, low silt:clay ratios, coarse fraction composition of over 25 percent biogenous constituents, and a dominance of planktonic foraminifera in the biogenous materials (Figures 12-15). Gray Silty Clay.The gray silty pebble clay occurs only on the steep walls of upper Astoria Channel within the gray silty clay stratigraphic section.The distinguishing characteristics of this group are that the sediments have the poorest sorting and coarsest size of any clay, a lack of skewing, and a coarse fraction which lacks biogenous material and has over 90 percent terrigenous material (Figures 12-

15). Olive Gray Clay (54 samples).This group is composed of clay layers of the olive gray clay stratigraphic section. This clay,similar to gray silty clay, has low silt:clay ratios, poor sorting and> 25 percent biogenous constituents in the coarse fraction.The olive gray. caly can be distinguished from the gray silty clay by its generally finer grain size, better sorting, negative skewness and higher quantity of biogenous constituents (Figures 12-15).

Composition

Mineralogy

Light minerals from the sand fraction of 22 coarse layers and a layer of gray silty clay with pebbles have been analyzed (Appendix

6). Most of the coarse layers contain mainly sand-sized materials, but several are coarse silt layers.All of the layers have tern- genous materials dominant in the coarse fraction. In general, the layers have the following mineralogical relationship: quartz > plagioclase > K-feldspar.The tuffaceous sediments from upper Astoria Channel (Appendix6: 196,202, and 205), and the pebble clay (Appendix6:112) have quartz > K-feldspar > plagioclase.The layers with ash have a very low plagioclase content (4 -6percent). Oligoclase and andesine are the most abundant plagioclases, but labradorite and albite are common.The upper fan coarse layers with ash and the pebble clay contain only oligoclase.Generally, the staining technique (Bailey and Stevens,1960)shows that Ga-rich rock fragments predominate over K-rich fragments just as Ca-rich feldspar predominates over K-rich feldspar.The tuffaceous sediments from upper Astoria Channel again are anomalous; they have a high 79 content of K-rich rock fragments, acidic pumice pebbles, and glass shards.This dominance of acidic volcanic material probably causes the different light mineral ratios. that the tuffaceous layers possess. The quartz:feldspar ratios usually are about 1, 0; quartz: feldspar plus rock fragments ratios generally are approximately

0. 4.The tuffaceous layers and the pebble clay layer have higher ratios of quartz:feldspar (1. 45 to 2. 54) than the other coarse layers. According to sandstone classification of Williams, Turner, and Gilbert (1958), the coarse layers analyzed for light minerals are mainly wackes (Appendix 7).Since quartz, feldspar, and rock fragments each constitute about one-third, the sediments group near the borders of arkosic and lithic types (Figure 17).The physiographic distribution of the different sandstone types of the 22 representative layers is given in Table 7.

Table 7.Physiographic Distribution of Sandstone TypesdfZ2Repe- sentative Coarse Layers from Astoria Fan (sandstone types after Williams, Gilbert, Turner, 1958, see Figure 17). Number of each sandstone type in each physiographic division of Astoria Fan Sandstone Upper MiddleLowerTotal Total % type Fan Fan Fan No. Analyzed

Arkosic wacke 2 1 2 5 23

Lithic wacke 3 1 3 7 32

Volcanic wacke 2. 2 9

Arkosic arentie 1 3 4 18

Lithic arenite 1 3 4 18 Stable Stable Quartz Quartz

U. Fai, Ca..,. La,

M4dI.&n On... L

Lent . Caar.. L.j

fly..fl. S2.flpI..

-- A.t.rla P.. a.ta.. Caay.n tC ,N 1 C.Inbt* n,

Unstable Feld Rock Feldspars ints ARENITE Rock Fragments

Figure 17.Triangular diagram of the composition oZ the light fraction of Astoria Fancoarse fractions, in terms of terrigenous constituents, and classification of petrographic sand types. 81 On the basis of silt and clay content all sands from the upper fan are wackes; about two-thirds of the sands from th middle and lower fan are wackes and about one-third are arenites (Figure 14). Analysis of coarse fraction reveals that most coarse layers have a composition of one-third or more rock fragments and therefore are lithic arenites or wackes.The average of the elected samples is a lithic wacke (Figure 17, see AF). Light mineral analysis shows that volcanic wackes of the upper fan vary most from the normal coarse layers.The content of plagioclase is much lower and the content of rock fragments is much higher than for normal coarse layers; K-feldspar > plagioclase and K-rich rock fragments > Ca-rich rock fragments, which is the reverse of the normal coarse layers.The quartz:feldspar ratios are significantly higher in the volcanic layers than in other layers, and the volcanic layers contain only oligoclase.Other tuffaceous sands of the fan probably have a similar content of quartz, feldspar, and rock fragments. Although quartz, feldspar, and rock fragment percentages vary little between the tops and bottoms of a single coarse layer, sand classification changes due to the change in the amount of matrix (material

6,352) to arkosic arenite at the bottom of a layer (Appendix 6,355) have been observed. Heavy Minerals. Varieties of heavy minerals from the total coarse fraction of 20 representative samples were estimated by counting 64 grains or more (Denison and Shea, 1966) (Appendices 4, 7).Fifteen of these samples were from coarse layers and five were from clayey-silt layers. In most coarse layers the following relation of main heavy mineral groups is noted: clinopyroxene > amphiboles > orthopyroxenes.In the coarse layers, the opaque minerals and rock fragments are as abundant as the main mineral groups; metamorphic amphiboles, garnet, epidote, zircon, apatite, and andalusite groups are present in small, but consistent amounts.The ash and pumice- rich layers contain fewer clinopyroxenes, more blue-green amphiboles, and more orthopyroxene than the normal coarse layers, so that amphiboles > clinopyroxenes. > orthopyroxenes. Again, variation from top to bottom within a coarse layer is as great as from layer to layer.Mica is abundant and the percentage of pyroxenes and amphiboles is diminished when the sand percentage is very low as it is in the top of graded layers or in clayey-silt layers (Appendix 7:31, 32, 72, and 73), Except for the clayey-silt layers, heavy mineral counts (Ap- pendices 3,4) of the coarse fraction always agree within five percent of heavy mineral weight percentages determined by heavy liquid separation (Appendix 7).In the clayey silts, the disagreement between the two methods for estimating amount of heavy minerals re- suits from the heavy liquid method which allows mica to settle with the heavy minerals.Coarse fraction counts show that clays and clayey silts are low in heavy minerals, whereas basal portions of coarse layers have the highest content of true heavy minerals. Volcanic Ash. A few interchannel silt layers from the upper and middle fan contain 75 percent or more volcanic glass and are classified as vitric ash(Appendix 8).Most of the ash layers are 25 to 75 percent ash and are classified as tuffaceous coarse layers (Ryan, Workum, and Her sey, 1965).Two layers in Astoria Channel possess less than 25 percent ash in the sand fraction, but contain pebbles of pumice.Several other channel layers have less than 50 percent ash.The channel layers with a relatively low quantity of ash have a higher percentage of terrigenous minerals and sand- sized materials, and are thicker than the ash horizons of the interchannel regions. One of the channel layers has.a mean grain size of sand and all other tuffaceous and vitric layers have a mean grain size of silt. The refractive index (RI) for all the volcanic glass is the same. The samples which were checked with coarsely calibrated oils have a RI from 1. 500 to 1. 510.With finely calibrated oils the glass shards have a maximum RI range from 1. 502 to 1. 509, and most range from 1. 504 to 1. 508.The mode of the RIis 1. 505 to 1. 507. Clays. A study of clays from Astoria Canyon and Fan by Kenneth Russell (1967) revealed that the clay minerals consist of nearly, equal portions of montmorillonite, chlorite, and illite.No mixed layers or regular or irregular interstratified clays were noted. The composition of clay varies slightly, with change in stratigraphy, but not with change in lithology and texture.X-ray traces of the gray silty clay have different peak characteristics for chlorite and illite than do X-ray traces for olive gray clay.The clays of the fan have the same general composition as the clays of the Columbia River.Russell (1967) found no evidence of diagenetic change from the river to site of deposition on the fan.

Displaced Benthic Foraminifera

General.Ecological zonation of recent benthic foraminifera has been established in continental terrace and.deep sea sediments off Oregon (Fowler, 1966; Hunger, 1966; Boettcher, 1967).From this information it can be determined whether or not' a deep-sea fauna has been displaced.In selected Astoria Fan sediments displaced benthic foraminifera have been separated from in situ species, identified, and estimated abundance (Appendix9). Dr. Gerald

Fowler(1966)has verified the identifications of displaced and in situ fauna. Most clays underlying coarse layers lack displaced benthic foraminifera and all clays have in situ. species predominant over displaced forms (Appendix9;74,. 122, and 172).Planktonic foraminifera are more abundant than benthic foraminifera in all clay layers.Inthe clay layers with rare displaced foraminifera, the coarse fraction had a high terrigenous content (Appendix9,300 and

350).This indicates, that coarse fraction material of coarse layer origin has been mixed into the clay by benthic activity, currents, or sampling procedures. Clayey silts usually contain displaced foraminifera, but these forms are less numerous than in situ benthic foraminifera.The displaced foraminifera of the clayey silts are smaller types. and often are dominantly upper to lower slope fauna. All coarse layers that have been examined, including tuffaceous layers, possess abundant displaced benthic foraminifera.In the coarse layers, displaced faunal groups indicative of distinct depth zones occur; two layers (Appendix 9; 73 and 118) have a dominance of inner shelf fauna; two layers (56 and194)have a dominance of upper slope fauna; and one layer (301) has a dominance of upper slopeouter shelf fauna. The displaced fauna changes from the bottom to the top of the thickest layer that was examined (Appendix 9; 350-355).Mainly inner shelf benthic foraminifera are found at the bottom of the layer and these constitute nearly the whole fauna (355).Through most of the upper part of the layer, amixed foraminiferal suite representing all environments is found (354-351).Clay several centimeters above the coarse layer has rare, small displaced benthic forarninifera (350). The terrigenous and platy-terrigenous content of the coarse fraction of the clays indicate that origin of the clay above the coarse layer is in part related to some type of current activity. The coarse layers lack arenaceous displaced benthic foraminifera.Duncan (1966) found that arenaceous foraminifera on Cascadia Abyssal Plain just west of Astoria Fan are not preserved beyond a few centimeters beneath the sediment surface.This phenomena may account for the absence of displaced arenaceous foraminifera in the Astoria Fan coarse layers. Summary of Characteristics of Displaced Foraminifera. Amounts of displaced foraminifera vary through a layer with the highest numbers in the coarsest material and the fewest in the finest "tail' material of a coarse layer.The types of displaced foraminifera also vary from one part to another part through a thick layer. Different, relatively, thin coarse layers have displaced fauna of different distinct depth zones.The clayey silts contain only. displaced species that have the least displacement from their original environment. Summary of Clays

The olive gray clay, (from the upper stratigraphic horizon on the fan) in general, is the best sorted, the finest, and the most negatively skewed clay.It is composed of nearly equal parts of montmorillonite, chlorite, and illite.The percentage of sand is the lowest for any clay, while the amount of biogenous material in the coarse fraction is. the highest for any sediment of the fan.Radio- larians are dominant in the coarse fraction. The gray silty clays differ from the olive gray clays by their color, lower stratigraphic position, coarser texture, anddifferent faunal composition.The quantity of biogenous constituents is lower and is made up mainly of planktonicforaminifera.The gray silty clay has different illite and chlorite X. ray patterns than the olive gray clay. The gray silty clay, with pebbles is the coarsest, most poorly sorted, least skewed, and least widely distributed clay on the fan. Its coarse fraction of nearly all terrigenousmaterialwitha few Iarge pebbles is. unique. 1 Horizontal and Vertical Trends

Texture of the clays becomes finer toward the lower fan and away from the continental slope; however, trends ofthe gray clay are coarser and less consistent than those of theolive gray clay. The gradation to finer sediment is revealed by the higher percentage of clay and the lower silt: clay ratios down the fan away from the con tinental slope (Figures 14,18,19).The olive gray clay is better sorted and more negatively skewed down the fan (Figures 12,13). The coarse fraction composition of the surface clay is grada tional away from the continental slope (Figures 18, 20, 21); the quantity of the major terrigenous materials (plant fragments, detrital minerals) decreases rapidly and the quantity of radiolarians increases rapidly.Gradation in some of the minor constituents, such as a lower content of pollen away from the continent, can also be detected (Figure 18).The changes in composition of surface clay from the canyon mouth to the lower fan, in most instances, arethe same as those away from the continental slope base.This occurs because the lower fan in most locations is at the greatest distance from the continental slope.Where the lower fan is adjacent to the continental slope, gradients trend west from the slope and not south from the canyon mouth (Figures 19-21). The similar trends of composition of gray silty clays do not a

0 10! * 0 8 z'I

'a, 0 'Ct

: $

I I I 0 ¶ 2 3 4 5 5 7 8 9 ¶0 SILT CLAY RATIO IN SURFACE CLAY GRAINS OF POLLEN IN SURFACE CLAY

'S 0 'a, 0 9 0

03 0

S . 'a. br.. * ,. $JLTCLAY RATIO IN PLEISTOCENE CLAY %RAOIOLARIANS IN SURFACE CLAY Figure 18.Lateral changes with distance fr':n the continental slope in surface postglacial olive gray clay (A, C, D) and glacial gray silty clay (13). I I I I I I I 127001 26OO 400 300 200 1100 000 L4 750/0

800/a

b00__

I50 5 00

S 000 I600 ' ) i' I 7 75°/o/ A S T 0 R / A '--/. -í I - FAN 650/0i J1300 80°/o 55°/o( 3400 (1500 550 Piston Core and Phieger Coresample station, 10 20 6509I - I NAUTICAL MILES Cqntour Interval 00 fathoms 50 fathoms 0 020 60°/c-Clay lnSurfce Samples KILOMETERS Compiled by Hans Nelson

Figure 19. Gradiation of clay percentage in surface sediments of Astoria Fan, 0/0DETRITAL GRAINS

12700 126 00 1300 1200 1100 1000

14J

tA 46 Q.. 0N

-4

Cl)

-4

1000

11400 500 550 9 la

PLANT FRAGMENTS

12700 26 00 1100 1000

0/0 IU A 46°00

-.4

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Lu l550\\'..

45.

------1600 A S To RIA5'°"----'.. 05°IoPlant Fragments 300 /11400 5100/o Plant Fragments (1500 10.200/0 Plant Fragments 1550 Piston Core and Phieger Core sample station 0 10 20 NAUTICAL MILES

Contour Interval : 100 fathoms ------50 fathoms 0 10 20 KILOMETERS Compiled by Hans Nelson

Figure 20 (a & b).Graç3.ation of coarse fraction terrigenous debris in surface sediments of Astoria Fan. 92

NOIL3VeI SeiVOD O VLNOd

0 (0

0 t1 (0

Lu 0 z -J 0 (0 I- 4 0 0 0 -J U- 'Ii 0 0

(0 0) 0 U, (0

0) 0 IL) (0 Figure 21.Coarse fractioncomposition of sirface sediments from the continental slope to Cascadia Channel.(see Figure afor core locations) ("other't constituents=foramini-. fera, authigenic minerals, and shell fragments) 93 have the consistent variation that the olive gray surface clays have. Disruptive density-current activity of past ages may have caused this, or distinct patterns may never have existed. Vertical changes in the clays occur because of the alteration in stratigraphy from olive gray to gray silty clay and because upper coarse layers grade gradually into clay sediment types.The clay- like lithology. immediately.above coarse layers usually conists of clayey-silt.This generally grades upward into gray silty or olive gray clay where coarse layers are widely spaced.Consequently, clay sediment types immediately underlie coarse layers that are well spaced, but they are found at a considerable distance above the underlying coarse layer andits clayey-silt tail (8G, a-c).Where the coarse layers are very closely spaced, gradation from clayey silts to olive gray or gray silty clay normally is not present.This is often the case at depth in the gray silty clay stratigraphic section; coarse layers become more numerous and closely spaced, and only clayey silts occur between them.

Comparison with Clays of Other Regions

Except for the gray silty clay, with pebbles, similar clay types are present in the region surrounding Astoria Fan,The gray silty clay with pebbles has been found only in the walls of upper Astoria Channel.Olive gray clays occur on the continental terrace, (Maloney, 1965; Runge,1966),in Astoria Canyon (Carson, 1967), over Cascadia Abyssal Plain (Kuim, 1967), and to the south in the Blanco Fracture Zone (Duncan, 1968).In general, the olive gray clay of the continental terrace, compared with that of the fan, is coarser with mainly silt and only 20-40 percent clay, and has a greater content of diatoms, glauconite, and terrigenous coarse fraction (Maloney,1965;Carison,1967). At the inner margin of Astoria

Canyon, the coarse fraction of the olive gray clay contains up to90 percent terrigenous debris and no biogenous material (Carison, 1967). The compositional gradation of surface sediments across the fan ceases midway from the base of the continental slope (Figures19, 20). The amount of clay (70-80 percent) and biogenous constituents in the coarse fraction (over 75 percent) remains nearly the same on the western part of the fan and on Cascadia Plain to the west of Astoria

Fan (Kulm and Griggs,1966). A upelagic? clay with abundant radiolarians and diatoms is observed in the upper 20-50 cm of Northeast Pacific abyssal plains (Hur1ey,i960).Beneath this is a gray clay that is coarser than the surfe pelic slay and that has a high content of terrigenous debris.Clay with pebbles also is noted in many regions of rough topography in the Gulf of Alaska.These sediment types seem to be the same as those of the fan. Wilde (1965) cited brown surface, olive drab pelagic, and gray 95 clays in Monterey Fan off the central California coast.He attributed the brown surface clay to changes in the oxidation state of the iron compounds, which also seems to be the case on Astoria Fan.It is difficult to correlate the clays of Monterey Fan with those of Astoria Fan because the stratigraphy of the former is not established and no standardized color descriptions were used. The outer fan in San Diego Trough off Southern California has hemipelagic olive silty clays that appear to be comparable with Astoria Fan olive gray clays.They are comparable in coarse fraction that has abundant radiolarians and diatoms, and in texture that is 50 percent or more clay, with silt:clay ratios of 1:1 or less (Shepard and Einsele, 1962).

Summary of Clayey Silts

The clayey silt group has end members that are gradational with clay and coarse layer sediment types; however, most sediments in the group are clayey silts or silty, coarse clays that are poorly sorted and positively skewed.The coarse fraction is composed of platy-terrigenous constituents and usually has displaced benthic foraminifera.The heavy mineral composition of clayey silts has a low Fe - Mg mineral content, but a high quantity of mica.The clayey silts are lithic or volcanic wackes by mineral and matrix makeup; as rocks they probably would be classified as mudstones or siltstones. Horizontal and Vertical Trends

The clayey silts become coarser down the fan as silt content increases and clay content decreases.Toward the lower fan, clayey silts overlying coarse layers grade from a high content of detrital constituents to a relatively high content of biogenous constituents. In the lower fan, clayey, silts interbedded between closely spaced coarse layers also contain a high amount of biogenous constituents compared with those on other parts of the fan. The clayey silts are the final gradational phase overlying a coarse layer.They have afiner texture than the coarse layer below because of more clay and less sand (Appendix 10).In the gradation from coarse layers to the clayey silts above, sorting becomes poorer, percentage of platy-terrigenous constituents increases, the amount of Fe-Mg heavy minerals decreases, and the number, type, and size of displaced benthic foraminifera decrease.The clayey silts always are lithic wackes, but they may grade below into coarse layers that are arenites or arko sic wackes.

Comparison with Clayey-Silts of Other Regions

Carison (1967) found the ciayey silt sediment type occurring as laminated gray silty clay in the Astoria Canyon region.It is 30 to 50 percent clay, 50 to 70 percent silt, and has chiefly mica and some 97 plant fragments in the coarse fraction.Hurley (1960) noted a sediment type between upelagict? clay and 'turbidity current?? deposits in the Northeast Pacific abyssal plains.He called these T!intermediateu sediments.The mean grain size near the silt to clay borderline and a coarse fraction principally of continental detritus with some pelagic contribution is similar to that of the clayey silts of Astoria Fan. Shepard and Einsele (1962) described a clayey- silt lithology in San Diego Trough that is most common in the fan and levees at the mouth of La Jolla Canyon.This sediment type has silt:clay ratios from 1:2 to over 3:1 and has a high mica content.The silt:clay ratios (Figure 14), the high content of mica (Figure 15), and the occurrence in levees near the mouth of Astoria Canyon all are similar in clayey silts of Astoria Fan.

Summary of Coarse Layer Facies

The sands, silty-sands, and sandy-silts of the middle and lower fan coarse layers have the best sorting of any sediment of the fan, a positive skewness, and a low clay content, which results in high silt: clay ratios.The Upper Fan coarse layers have finer mean sizes, are more poorly sorted, are more positively skewed, and contain more clay than middle and lower fan coarse layers (Figure 14).High clay content of upper fan coarse layers results in the characteristic mean size of medium silt and low silt:clay ratios.Many of the upper fan coarse layers have a high quantity of ash and pumice, while only a few of the middle and lower fan coarse layers are tuffaceous.The tuffaceous layers of either type of coarse layer have a lower plagioclase content and often a higher hypersthene contentthan other layers. The coarse fraction of any coarse layer is composed predominantly of terrigenous materials, but upper fan coarse layers have less terrigenous material than middle and lower fan coarse layers (Figure 11).A dominance of displaced benthic foraminifera is found in all coarse layers.

Horizontal Changes in Coarse Layers

The coarse layers exhibit textural, compositional, and stratigraphic changes from the upper to lower fan.The greatest changes progressing down the fan occur in the interchannel regions.The interchannel coarse layers of the upper fan are few in number, thin, and silt-sized (Figure 10; Table 8 and Appendix 11).Thick sands occur everywhere in or out of channels in the middle and lower fan (Figure 10; Table 8 and Appendix 11).The clay content of the channel and interchannel coarse layers decreases from the upper to the lower fan, producing ageneral increase in silt:clay ratios down the fan (Figures 14 and 22).The most poorly sorted group of sediments of the fan, the upper fan coarse layers, grade down the fan to the best sorted group of sediments of the fan, the middle and lower Table 8.Average Amounts of Coarse Layer Lithology in Different Physiographic Regions of Astoria Fan

- 0 a.) a) a.) Depth in core - Depth in core Depth incore O o a) Qu 4., a) ad a) E E E a ci ci ad Fan U a) _, , u 0 0 0 0 0 0 -'4- 0 0 0 0 0 0 Region 0 0 0 0 00 0 0 0 0 0 0 0 o o 0 '-4 CO 1' LI) '.0 0 0 -i c..i eo 'ad' LI, O 0 - CI CO ' LI) '.0 ' 0 0 C'.1 'tar Average total number of Total thickness of coarse Average thickness per coarse coarse beds in each 100 beds (cm) of each 100 cm bed (cm) cm of core of core Ijiterchanne 1

Upper fan (4) 1 2 2 3 0 0 8 7 5 2 3 0 0 5 7 20.7 0.3 .0 0 2

Middle fan (9) 4 5 4 4 4 3 24 16 16 20 26 14 19 22 5 3 7 10 4 6 6

Lower fan (8) 2 3 4 0 44 9 17 30 47 0 0 0 34 8 9 16 0 0 0 10

Channels

Upper fan (3) 3 5 0 0 0 0 8 27 78 0 0 0 0 49 10 20 0 0 0 0 9 ** Middle fan (1) 1 1 0 0 00 2 12 0 0 0 0 21 10 20 0 0 0 0 15 0** Lower fan (4) 2 4 3 2 0 0 11 16 40 37 71 0 41 4 13 17 24 0 0 11

*All data given is from 4 upper fan cores containing coarse layers, 4 additional upper fan cores containing no coarse layers; considering all 8 upper fan cores would reduce all upper fan values by 1/2 ** In centimeters, thickness of coarse beds per thickness of lowest section of core. 100 CHANNEL LAYERS (Postg'acial) 2 1

Z2 w

,KM Iqo 1O INTERCHANNEL LAYERS (G$acial) 2- 0 o - 0 3-

0 0 00 z 4-

0 0 6-

0 0

40- 0 0 30-

20- 0 0 0

0 1O 0 0 00 0 0 a 0- 50 1IO 150 KILOMETERS DISTANCE FROM CANYON MOUTH

Figure 22.Textural gradation with distance from the fan apex in the coarsest layer at each core location. 101 fan coarse layers (Figures 11 and 16). A decrease in positive skew ness also occurs between these two groups (Figure 13) In Arsto r'i'a.:; Channel beyond the point where the upper channel gravels occur there is little change in thickness and coarseness of the base of the coarsest layers (Figure 12).The silt and clay content, and the sorting of these coarsest layers change. slightly toward the lower fan; the clay, content becomes consistently low and the mean grain size of coarse layers remains consistently high on the lower fan (Figure 22). The composition of coarse layers becomes slightly higher in detritals. and lower in biogenous and platy-terrigenous constituents progressively down the fan (Figures hand 15).All the upper fan coarse layers are wackes.while some middle and lower fan coarse layers. are arenites (Figure 17).The heavy mineral content of the coarsest.layers usually, is less in the lower fan than.it is higher on the fan.(Appendix 10).

Vertical Changes in Coarse'.Layers

Texture.The general change in lithology from coarse layer to clayey silt above (Figure 8G, b-a) substantiates the vertical size grading of coarse layer sequences (Appendix 10).The basal contact of the coarse layers with underlying sediments. is sharp, whereas the tops of the layers grade into clay (Figure 8G).Sorting becomes 102 poorer from bottom to top of the layers (Appendix 10). Size grading takes several forms.In layers over several centimeters thick the grading usually occurs in intervals, with some parts of the layers showing little gradation and other parts exhibiting definite gradation (Figures 8G, 23A, and 24).At the top of the layers the gradation is even, but rapid, as the san content decreases quickly, clay content, and silt content decreases in silt-sized coarse layers increases in sand-sized layers (Figures 25 and 26; Appendix 10).At the bottom of the layer, coarse material tends to be more massive in structure and graded very gradually, if at all (Figures 8G; 23A, B; 25; 26; and Appendix 10). Lamination is most common in the upper part of coarse layers (Figure 23A, D and E).It usually is caused by clay-rich laminae in the silts.Normally, lamination is lacking in the coarser material in the lower part of a coarse layer (Figures 8G and 23A).The finest laminations may be < 0. 5 mm thick in silt layers (Figure 23D and E). Coarsest laminations occur in coarse layers of the channels and often are up to 5 mm thick (Figures 23A and 24B, D),Such coarse lamination appears to be characteristic of the main fan valleys and of Cascadia Channel (Kuim, 1967).Coarse layers of the lower fan and upper channels tend to be the coarsest of the fan; they often lack lamination (Figure 8F-H). Convolute lamination is common, but usually is found in cores Figure 23.Representative sedimentary structures of Astoria Fan coarse layers.

A.graded sand layer (b) from lower fan with basal contact exhibiting cut and fill structure.Layer (a) above shows normal flat basal contact - core C-4; B.lower fan coarse layer with middle part showing cut and fill of medium size sznd. Note cross-bedding in silt and sand of lower half of layer- core-4-2; C.lower fan coarse layer containing mud clasts - core A-5;

D. Coarse layer from inter-fan valley ridge of apex region.Note cross-bedding, lamination, and Bouma (1962) sequence of structures (see Figure 24)- core A-i; E.middle fan silt layer with criss-cross bedding" of Heezen and Hollister (1964, cf. p.170, figure 17B).Dark clay laminae outline the cross-beds and lamination- core K-i. iii r

a 70

210..._.L

Dept 1-n Cor E

nil \

513

Clay I Laminae

516 CUT AND FILL

CROS S-BEDDING Figure 23.Representative sedimentary structures of Astoria Fan coarse layers. 0 105

PELITIC INTERVAL 402CM _____

/ fl / / / M =5.07/ / 74% sil/ D UPPER INTERVAl OF PARALLEL LAMINATION

Figure 24. Coarse layer from lower Astoria Channel (core 6509-4) illustrating D UPPER INTERVAL Bouma (1962) sequence of turbi- OF PARALLEL dite sedimentary structures. LAMINATION

Notevery top part of layer was flipped to a vertical position by the coring operation.

C INTERVAL OF URRENT RIPPLL a LAMINATION

B -at- LOWER INTERVAL OF PARALLEL 4. . k LAMINATION

M=33,,,/ - :. 70% sand A GRADED OR

: INTERVAL CORE C-3 % COARSE FRACTION %COARSE FRACTION 0 20 *0 00 80 100 I I I CORE 03 (2 Coor.. L.y.r.) *03

1 OfSAND

z °lo SAND 0 O CORE 65095

4 ! VoI.*GI.

Io SAND

SAND Figure Z5,Gradation of coarse fraction and sand content in typical Astoria Fan coarse layers. 107

% ol Coarse Fraction

0 20 3)) 40 5)) 425

443

438

I 444 P in I

iq I

453

465'-- Sample Oepth % Serrd Nosed t Location

['igu e 26. Gradation of coarse fraction, sand content, and displaced benthic foraminifera in a thick sand layerof lower Astoria Channel.Occurrence within layer of each foraminifera species and qualitative amount throughout range of occurrence are shown by arrow length and letter at the arrow head.Letters midway in range line show change from usual relativequantity of a species.(a = abundant, ccommon, r = rare) disturbed by coring anomalies or burrowing of organisms.Because these artificial disruptions can give an appearance similar to convolute lamination, the structures cannot unequivocally be attributed to normal depositional processes. Cross-bedding is most prominant in the coarse silt portion of the upper part of thick coarse layers, and in coarse layers with mainly coarse silt-sizematerials (Figures 23D, E and 24C); it may occur in lower portions of thick layers if they are silty (Figure 23B). The cross-bedded section usually ranges from one to four cm thick and most cross-bedding is a type referred to as Itcurrent ripple lamination by Bouma (1962) (Figures 23B, D and E).Heezen and Hollister (1964, p.170,. Figure 17B) defined a type they call "criss- cross bedding. "This appears to be present in some layers on Astoria Fan (Figure 23E).Bouma (1965, p. 308, Figure 11) showed photos of cross-bedding similar to Heezen and Hollister's "criss- cross bedding,Ubut he makes no distinction of it as a special type. Evidence of cut and fill structures is present at the basal con- tactsofsomethicklayers(Figure 23A). The irregularity of the contact indicates s c o u rpreceded the deposition.Occasional, sharp changes in coarseness with uneven bedding contacts in thick coarse layers also suggest scour and fill within a continuous coarse layer (Figure 23B).Material in the apparent cut and fill is usually massive, clean, and coarser than the surrounding material. 109

Mud clasts are found in some thick coarse layers, although the possibility that they may be associated with coring anomalies cannot be eliminated.The mud clasts bounded by horizontal bedding appear to be valid in situ examples (Figure 23C). Mottling, probably from burrowing activity, appears to be restricted to the olive gray clay horizon (Figure 8B).It is best de- velopedin the channels where the greatest section of olive gray clay is found.Fecal pellets often are associated with the mottling that disturbs bedding and disrupts coarse layers. Composition. Marked changes in composition from bottom to top of coarse layers have been cited throughout the text.These gradational characteristics are summarized in Figures 25 and 26;

Table9;and Appendix 10.

Comparison with Coarse Layers of Other Regions

Sediments in the areas surrounding Astoria Fan have coarse layers similar to the middle and lower fan coarse layers, but dissimilar to the upper fan coarse layers that have a high clay and gravel content.Even near the mouth in Astoria Canyon, the coarsest layers are very fine sand or silt (Carlson,1967). The middle and lower fan layers are typical not only of the fan and abyssal plain region off Oregon (Hurley, 1960; Kulm and Griggs,1966;Duncan,

1968)but appear to be common in canyon, deep-sea fan, and abyssal Table 9.Vertical Gradation of Composition and Texture in Coarse Beds of Astoria Fan and Other Recent Sediments asxl Rocks from Similar Environments.

TEXTURE COMIOSiTION Foramsmfera_ Grain Matrix Sorting Skewness Sedimentary Coarse Fraction LightJ Heavy/ Planktonics #DisplacedSpecies Size of Size 1/ <20p1/ 1/ Structures - - jj 1/ 1/ Minerals Minerals Benthic Suites Species

Gradational top fine high poer positive laminations high content of lithic low high high low all only Feature of to cross-beds of platy-terrigenous wackes quantitymica and envir- small Astoria Fan very (ash, mica, of opaques onments sizes Coarse Layerbed p00: plant fragments heavies to maximums > 6O°t

bot- coarse low moderate slightly massive low content of arkosic high high low high only all torn positive platy terrigenous or quantitypyroxenes sped- sizes of (ash, mica, lithic of and fic plant fragments arenites heavies amphiboles envixon- bed to minimums or mcnts <59) wackes

Investigator many Bouma ash; Ryan etal. Wild Bandy Bandy Holter.- with similar studies (1955) (1965); mica: (1965) (1964) (1964) dahi observation see convolute Shepard C Einsele (1965) in recent Kuenen lamination: (1952) ;Wilde (1965); sediments (1964) Van Straten mica and plant (1964) fragments: Gorsline (1958)

Investigator Bourna Bouma mica and plant Natland change in mineral Nat- with similar (1962) (1952) fragments: (1963) suites:Stanley (1963) land observation for Snavely, Wagner (1963) in turbidite summary and MacLeod(l964); rocks plant fragments: Meischner (1964)

LI see Fisres 24, 25, and 26, Appendices X samples 11,12, 286, 287 and VIII samples 377 and 379. Vsee Appendix VII samples 27, 28, 31, 32. see Appendix VI samples 76 and 77. ',see Figuns 26 and AppendIX samples 35. 71, 351 to 355. II' plain regions throughout the world as well (Shepard, 1961; Hubert, 1964; Kuenen, 1964). In general, the deep-sea sands on the fans near the continent of western North America havealow organic content (Figure 15; Appendix 3 Shepard and Einsele, 1962; Wilde, 1965), but they, do commonly contain shallow water benthic foraminifera (Appendix 9; Shepard and Einsele, 1962; Bandy, 1964; Carison, 1967).Displaced foraminiferal faunas are common in the sands of Astoria Fan and the adjacent regions (Carison, 1967; Duncan, 1968).Bandy (1964) found an average of 78 percent displacedbenthic foraminifera in sand beds of deep-sea fans off Southern California.Similar to Astoria Fan, he also reported that over one-third of the displaced forms are paralic andinner shelf species.Displaced benthic foraminifera often have been reported from coarse layers of other regions similarto Astoria Fan, but abundance and type are not quantified (Ericson, etal., 1961; Kuenen, 1964). Differences are noted when the horizontal textural trends of coarse layers from Astoria Fan are compared with those of similar physiographic regions.Increasing fineness of coarse layers with distance from the source isa commonly mentioned change (Kuenen, 1964; Walker, 1967).Very, coarse layers are found in the channels of the Astoria Fan apex region, but beyond this point, size changes very little down the fan (Figure 22).Hand and Emery (1964) 112 reported the occurrence of a similar, rapid change in size in the first 10 km and then little or no change for 60 km. Most investigators have stated that sorting improves away from the source

(Kuenen,1964),but Sutton(1964)found deep-sea sands more poorly sorted in a seaward direction from the shelf.The deep-sea sands of Astoria Fan are generally more poorly sorted than the shelf sands

(Runge,1966),but sorting of the coarse layers on the fan improves considerablyaway from the fan apex (Figure 11).The clay content of coarse layers exhibits a similar pattern; fan sands have more clay than shelf sands, but the amount of clay decreases down the fan (Figure 14).This has not been emphasized in the literature (Kuenen,

1964). There is lateral variation to the composition of deep-sea sands, but consistent variation has not been observed. A decrease in the percentage of heavy minerals from the shelf off Nova Scotia seaward to the abyssal plain was reported by Sutton(1964). Percentage of heavy minerals changes only. slightly to the middle of Astoria Fan; then it decreases down the fan (Appendix 10).Wilde(1965)found that the content of mica in the sand increases toward lower Monterey Fan. The reverse appears to be true on Astoria Fan (Figure 15).It is apparent that lateral trends of texture and composition for deep-sea sands have not been studied sufficiently to determine if there are good general trends.The most reliable lateral trends for deep-sea 113 sands appear to be stratigraphic changes away from the sediment source.These will be discussed after a summary of fan stratigraphy. Investigators of deepsea sands and rocks from environments simi1ar to Astoria Fan also report vertical grading in texture and composition of coarse beds; these observations are cited in Table 9. As in similar environments, evey coarse layer of Astoria Fan does not have the complete vertical sequence of sedimentary. struc tures that Bouma(1962) noted; however, usually part of the sequence of structures is present(Figures 23and 24).The abundance of some of these structures varies regularly down the fan in the same manner that Walker (1967) described for turbidite environments. Mas sive bedding is the most typical of the upper andlower fan.Walker (1967) listed lamination and ripples as characteristic of proximal beds, but in Astoria Fan the best development of grading, lamination, and cross-bedding occurs more distally in the middle fan region. 114

VL STRATIGRAPHY

Correlation and Age of the Stratigraphic Units

The general stratigraphic relations have been outlined previously and sediment types of Astoria Fan and the surrounding regions have been compared.Both the olive gray clay and the underlying gray silty clay contain characteristic faunas, can be correlated over the fan and surrounding regions, and can be assigned geologic ages.Radiolarians and diatoms are dominant in the coarse fraction of the gray clay; planktonic foraminifera are dominant in the coarse fraction of the gray clay.Northwest of Astoria Fan the same stratigraphy was noted by Nayudu(1964)in the region 1300 to 150e W and 46° to 480 N.With radiocarbon methods he dated the top of the foraminifera-rich gray clay section at 12, 400 ± 375 years B. P. and the bottom of the gray clay at 26, 950 ± 1000 years B. P. From this

Nayudu(1964)concluded that the olive gray clay above the gray clay represents postglacial times, and that the globigerina-rich gray silty clay sediment corresponds roughly to the Vashon (late Wisconsin) glacial times. Recently, varying thicknesses of the same stratigraphic horizons from the region surrounding Astoria Fan have been dated by radiocarbon methods and studied for radiolarian: foraminifera content (Kuim and Ne1son,1967,Figure 27; Carlson, 1967; Duncan,1968). 115

FAUNAL TRENDS TENTATIVESTRATIGRAPHY OFF OREGON

IS2OO BP (±460)

1] CORE LENGTH 11 II 0 CORE 4$45 BP LENGTH ' 0 POSTGLACIAL 0 (±190)H POSTGLACIAL- TRANSITIONAL 0 PLEISTOCENE 20400 EP (±1.500)

LI RADIOLARIA PLANKTONIc FORAMINIFERA

COARSE LAYERS SAND LAYERS L

11 CORE LENGTH CORE

I LENGTH M o Li SAND

12 21 [3

SAND - MEDIUM SILT

TUEFACEOUS SILT

RATES OF SEDIMENTATION

A,200 BP (t 460) 6.60 Li BP[J26

11104 CORE - 170 CM/00 YRS LENGTH

L TUFTS OREGON 4.645BP ' [I POSTGLACIAL (±190) 2 POSTGLACIAL- TRANSIT IONAL ABYSSAL PLEISTOCENE CAPE PLAIN 20,400 AP 1500) MT MAZAMA ERUPTION

Figure 27.Comparison of Astoria Fan and Cascadia AbyssalPlain channel and interchannel Ethology and stratigraphy, (adapted from Kuim and Nelson, 1967) 116

These studies substantiate Nayuduts conclusions that olive gray clay with radiolarians and diatoms is postglacial in age and that the underlying foraminiferal gray silty clay is late glacial in age. In the channels, in particular, evidence from lithology, ratios of radiolarians, planktonic foraminifera, and radiocarbon dates shows that there is a transition period between well-defined late glacial and postglacial sediments (Duncan, 1968; Kuim and Nelson, 1967; Figure 27).Duncan (1968) believed that the period extended from 12, 500 15, 000 B. P. and that the best arbitrary date for the onset of the postglacial was about 12, 500 B. P.This boundary is defined bya radiolarian:foraminifera ratio greater than one, when no radiocarbon dates are available (Duncan, 1968). A gray clay with a low quantity of planktonic foraminifera that is older than 25, 000 - 27, 000 B. P. was penetrated by cores near Astoria Fan (Duncan, 1968; Kuim, 1967).This gray clay, which may represent thelast interglacial of the late Pleistocene, was not reached by the 6 rn cores on Astoria Fan. Since stratigraphic, lithologic, and faunal relations are the same in sediments of the region surrounding Astoria Fan, the age data have been extrapolated for the correlative stratigraphic horizons of Astoria Fan.The olive gray clay of Astoria Fan is considered to be a postglacial deposit beginning about 12, 500 years B. P.The gray silty clay is considered to bea late glacial deposit with the 117

deposition beginning sometime after 25, 000 to 27, 000 years B. P.

Establishment of a Correlating Ash Horizon

Layer by layer correlation of coarse layers from core to core generally is impossible (Figure 10).Even when two undisturbed piston cores were taken at the same station and the ship's drift was no more than a mile, coarse layers could not be correlated layer for layer (Appendix 1; Figure 2; C-4 and C-4-2).This suggests that lack of correlation occurs because of rapid changes in stratigraphy and lithology, possibly due to channel development. In many places on Astoria Fan and the surrounding region, the shallowest coarse layers are correlative even though they vary in thickness, coarseness, and stratigraphic depth.This is because they contain a significant quantity of the same ash (Appendix 8). Vitric ash and tuffaceous coarse layers are present over most of the upper and middle fan to about 60 km from the fan apex; they are found throughout the 160 km length of Astoria Channel (Figures 28 and 29).Ash-rich layers are absent in a few of the areas of steepest topography on the upper fan; possibly some of these layers are lost by slumping or erosion.In the few upper and middle fan locations where ash has not been detected it is also possible that thin iaminae with glass have not been noticed in core logging, or that ash laminae have been intermixed and masked by other sediments because of 118

/270 /260

(33) (170) 460

(2) C7 -.uII/ ASTORIA (80) \(76))0l3i) 0 (69)(2) *

(50)(2) (I) () i l(2) (68) j"2P"it46)

c')r F DEPTH OF []%SAND (100) I. ASH LAYER U -j (II) (17 (CM) I I f d '-L I I( \ 1- (sc*LJ p z -J -w PERCENTGLASS ('38) < OF SAND FRACTION (54)(7) I- 0-25 (72)S('5) z 1000 25-75 - - >75 00 U

CONTOUR INTERVAL- 100 fms 1500

Figure 28.Distribution, depth, thickness, andquantity of volcanic glass in representativeash layers of Astoria Fan. Symbols showcore locations, solid black circles representiritercharznel cores, and thetas represent channelcores. 119

12R° 124°

RTA 1. 444 -' f

!!1T 7 i ASTORIA

CASCADIA0 . ::::::.' 0 0 jI FAN : :: _/O I / A B V S S A L :.::::::::::.:.:.. 0 I

I ._.1

TUFTS6Q0'.w.w::1 I ABV5 4

I \ \ I, SUBMARINE FEATURES ) Iy. / MOUNTAINS 4 Lo7 HILLY AREAS 6'1 .. ORE OEPRESSIONS >200 FMS2 ABYSSAL PLAIN CONTOUR I CALj r.:::::o: .:::::.:.:::.y ( INTERVAL 00 FATHOMS ,' \ I','. ,I) I'o 24°

Figure 29.Areal distribution of Mazama ash.Solid black circles indicate pistoncores containing volcanic glassopen circles represent cores devoid of ash.Insert in upper left-hand corner showsarea affected by pyroclastic fallout of Mazama ash. (modified after Fryxell, 1965) 1 20 burrowing organisms.Ash. has not been found in the lower fan except in Astoria and Cascadia Channels.Numerous tuffaceous layers are noted throughout Cascadia Channel bordering Astoria Fan (Kuim and Nelson, 1967; Figures 27,29, and 30).Ash also occurs in the sediments of Astoria Canyon and its tributaries, and it has been reported in Willapa Canyon (Royce, 1967) and Blanco Valley (Nelson, etal., 1968; Figure 29). The ash can be correlated over Astoria Fan and adjacent regions by its stratigraphic position midway within the postglacial sediment and by its refractive indices (Figure 30).The refractive indices have already been shown to be the same over the fan (Ap- pendix 8).Similar indices are reported for sediments in the following nearby areas: Willapa Canyon (Royce, 1967), Astoria Canyon (Carlson, 1967), Blanco Valley (Duncan, 1968), and Cascadia Channel (Kuim and Griggs, 1966). The volcanic glass is correlative by refractive indices, by radiocarbon dating, and by. stratigraphic position with the continental deposits of Mazarna ash from the eruption of Mt. Mazama 6600 years ago (Rubin and Alexander, 1960; Fryxell, 1965).R. E. Wilcox (1966) determined indices of refraction of representative samples of the deep-sea glass to be mainly between 1. 502 and 1. 509±. 001.Additional refractive index determinations made by all investigators (Nelson, etal., 1968) on the glass shards found 0 (3)

(5 (3)! (58 (2)

(3) (I)E --vffil______

U) Ui w z I- Ui I. I (6) - 9670 BP (6) ±190 I-I3- zC, Ui -J Ui ('3) 0 ii CASCADIA (10) CHANNEL

I'<46456P ASTORIA I9° I I (t)kzzz CHANNEL

PERCENT GLASS OF ...... (23) SAND FRACTION IN ASH LAYER 6 CASCADIA V///A 0-25 (TERRIGENOUS) INTERCHANNEL

Wj'7A25-75 (TUFFACEOUS) 11840 BP <±210 >75 (vITRIC) SANO OR SILT LAYER BLANCO VALLEY WITH NO GLASS

Figure 30.Vertical distribution and age correlation of Mazama ash in selected cors from the deep-sea floor off Oregon. All cores shown are postglacial in age except core 3 which includes a thick section of late glacial deposits.Radio- carbon dates are given for four cores. N 122 in more than 50 cores show that the model values of samples lie be- tweeni. 505 and 1.507 ±. 002.These model values are similar to those reported by Powers and Wilcox (1964) for Mt. Mazama. ash. The glass in the marine environment commonly occurs as colorless, angular shards, fibrous columnar-like shards, and chunks of pumice. Pumiceous glass shards were examined by Steen (1966); they have physical characteristics that resemble Mazama shards and they. have indices that fall within the range of the indices given by Steen and Fryxell (1965) forMazama ash. Radiocarbon dates and stratigraphic position of. the deepest marine ash layers indicate that the time of the first occurrence of the deep-sea ash is about midway in the postglacial period (Figure 30); this also correlates with the time of the Mt. Mazamaeuption (Rubin and Alexander, 1960; Powers and Wilcox, 1964; Steen and Fryxell, 1965). Another recent large ash fall is that of Glacier. Peak, which occurred in northwestern Washington 1 2, 000 years B. P.(Wilcox,

1965).Glacier Peak ash, if present on Astoria Fan, should occur at the base of the postglacial section and would have different refractive indices than glass of the fan.The wide distribution of the Mt. Mazama ash (1 x 106sq. ml.), the location, and the size of the eruption (11. 7cu.mi,ejected, Williams,. 1942) which destroyed a mountain, are not. comparable with the Glacier Peak eruption.The 1 23 Glacier Peak eruption was remote from the offshore Oregon region, was not a cataclysmic eruption, and was more limited in distribution (2.5 x 10sq. mi4 than was the Mt. Mazama eruption (Fryxell, 1965, Figure 29).All the data refute the likelihood of a Glacier Peak ash source for Astoria Fan. Ash bed stratigraphy, physiographic distribution, and lithology indicate that deposition of ash was intermittent over a period of time and was accomplished by density currents rather than by airfall of pyroclastics.Substantiation and discussion of this mechanism will be given in the sedimentary processes section of the paper. The time of emplacement of the ash-bearing density currents must be known if theash is to be used as a precise stratigraphic marker in the marine environment.The mere presence of Mazama ash in the deep-sea sediments indicates that the deposits above the ash are younger than 6600 years.However, radiocarbon dates ob- tamed in two cores from Cascadja Channel and one each from Astoria Canyon and:from Blanco Valley (Figure 30) indicate that the first ash was emplaced before 5600 B. P. and after 9700 B, P. (the radiocarbon dates are rounded to the nearest 100 years).If a constant rate of sedimentation is assumed in postglacial time, the lowest ash layers would be 7300 and 6200 years old, respectively.Using similar reasoning, Royce (1967) arrived at a date of 7360 ±. 300 years B. P. for the ash layer in Willapa Canyon.These ages are 124 comparable with the 6600 year radiocarbon age of the Mazama ash in continental areas if one takes into account the inaccuracies inherent in assuming a linear rate of sedimentation during postglacial time.Radiocarbon dates and stratigraphic position both suggest that the first ash flow occurred shortly after the Mt. Mazarna eruption (Figure 30).

Summary of Astoria Fan Stratigraphy

In the interchannel regions of most of the fan the postglacial clay is approximately one meter thick (Figures 9 and 10).The lower fan, the walls of the main channels, and the lower edge of the continental slope have slightly less postglacial clay than other interchannel regions.The main fan valleys are covered by three to four times as much postglacial clay as the interchannel areas, and the lowest ash layer is three to four times deeper in the channels.Late glacial clay was penetrated only in interchannel areas, and this clay with pebbles was found only in the walls of upper Astoria Channel. Most of the proximal to distal, and channel to interchannel trends of coarse layer stratigraphy are given in Table 10.The postglacial clay in the interchannel regions usually lacks coarse layers except for thin vitric and tuffaceous silt layers (Figure 28).In the main channels thick coarse layers, some of them tuffaceous, extend throughout the fan (Figures 10 and 28).In the late glacial clay of the 125

Table IQ Comparison of Proximal and Distal Stratigraphy of Astoria Fan Feature Proximal (Upper Fan) Distal (Middle and Lower Fan) Compared Channel Interchannel Channel Interchannel

A.General A few deep, narrow channels in Many broad shallow distributaries stratigraphic clay beds with silt laminae with cut and fill channeling setting throughout section

B.Amount of Mainly coarse Lack of coarse Thick clay and coarse layer sections coarse beds beds beds about equal C.Thickness of Beds thick Thin laminae Beds thick coarse beds

D.Cyclic nature of Beds irregular Laminae very Beds regular in thickness coarse beds iii thickness regular

E.Development of Clay partings Mainly clay with Clay partings well developed clay partings be- between layers a few silt and distinct tween coarse poorly developed partings layers

F.Upper and Base of coarse layer sharp and top Base of coarse layer sharp; lower Contacts often sharp grades into clay at top of coarse beds

G.Meansizeof Beds with Beds with fine Beds with very Beds with coarse beds gravel size silt size fine sand medium sand (postglacial) ((glacial) H. Grading of Beds ungraded Beds too thin Beds with well developed grading coarse beds or Crudely graded for grading I.Sedimentary Laminations and Laminations Laminations and cross-bedding st'uctures of cross -bedding very frequent comm on coarse beds infrequent J.Channel wall Ice-rafted sedi- No ice-rafted sedimentsnor distinct channel sediments ments in channel wall facies wall K. Ash layer Thick pwnaceons Thin ash layers Thick ash No ash layers- stratigraphy ash layers with lower fan twigs Thin ash layers middle fan

L. Ratio of High coarse Very low coarse High coarse layer: clay ratio coarse: layer: clay ratio layer: clay ratio clay layers M. Changes in\ Increasing number of coarse layers with depth coarse layer N. Increasing thickness of coarse layers with depth stratigraphy( 0. with dePthJ Increasing coarse layer to clay ratio with depth 126 upper fan normally only silt and organic laminae are found.The late glacial clay of the middle and lower fan has numerous coarse layers which increase in number and thickness at depth (Table 8; Figure 10).

Comparison with Stratigraphy of Other Regions

Compared to the floor and walls of the fan channels,a thicker postglacial section and finer coarse layers are present on the canyon floor, and a thinner postglacial section is noted on the canyon walls (Carlson, 1967).In contrast to the numerous, thick coarse layers of the fan valleys, only. the upper portion of the canyon that cuts into the shelf and the canyon mouth contain any thick coarse layers. Thin, ash-rich silty, laminae and ash-rich clay zones delineate the Mt. Mazama event in the postglacial section of the canyon (Carlson,

1967). Cascadia Channel, similar to Astoria Canyon, has a thicker postglacial section and generally has finer coarse layers than are found in the channels of Astoria Fan (Kuim and Nelson, 1967; Figure

27).Sand layers are present in the channels of Astoria Fan, but few are noted in Cascadia Channel (Kulm and Nelson, 1967; Figure 27). At one location in Cascadia Channel neither the first Mt. Mazama ash horizon nor the lithologic and faunal transition zone was reached within 5. 5 meters. of the surface.Generally, in Cascadia Channel 1 27 only thin ash-rich clay and silt horizons have been found (Kuim and

Nelson,1967,Figures 27 and 30).These numerous, tuffaceous clayey silts occur in the most recent postglacial sediments of Cascadia Channel as well as Astoria Canyon (Figure 30).Presence of sand layers below the ash layers and lack of them above ash layers in the fan channels, and presence of thick postglacial sections with recent deposition of ash in Astoria Canyon and Cascadia Channel suggest that high energy sedimentary processes have varied from one valley region to another during postglacial times. The thickness of the postglacial section increases near the continental margin and decreases west of Cascadia Channel (Kulm and

Nelson,1967;Figure 27).In the interchannel regions of the lower fan and to the west of Cascadia Channel, the postglacial clay lacks coarse layers and ash horizons (Kulm and Nelson,1967;Figures 27 and29). The late glacial sediments on both sides of Cascadia Channel contain increased amounts of sand and an abundance of coarse layers compared to postglacial sediments.Sand-size layers have been found only in late glacial sediments to the west of Astoria Channel; near the continental margin of the southern fan, sand-size layers occur in postglacial transitional sediments, but not in the postglacial sediments (Figure 27).Again, the variance in distribution of ash and coarse layers with time and location indicates that there were differences in sedimentary processes between the late 128 glacial and postglacial time,and between different channels during deposition of the ash.These variations will be discussed after sedimentary processes have been explained. The same general stratigraphy is noted to the south of Astoria Fan in the trough region between the continental margin and the Blanco

Fracture Zone (Duncan,1968). In the Blanco Fracture Zone some depressions have at least nine meters of postglacial clay, while the regions of high relief may have almost no postglacial sediment

(Duncan,1968). Apparently, all topographic lows, such as. channels, of Astoria Fan and the surrounding deep sea region have had much greater postglacial rates of deposition than topographic highs or flat areas. In the ridge and depression regions of the northeastern Pacific Ocean, the stratigraphy is generally similar to the fan.However, slightly less (20 to 50 cm) postglacial olive gray clay overlies the gray glacial clay (Hurley 1960). Although sediment types are similar to Astoria Fan, the same stratigraphy has not been extended southward into the Monterey Fan region (Wilde,1965). Some stratigraphic trends similar to those in Astoria Fan have been observed in other deep-sea fans and in the rocks of fossil fans. Primarily coarse layers are observed in the present main channels of the Congo Fan, San Diego Trough, Monterey Fan, and the Rhone

Fan (Heezen, etal.,1964;Hand and Emery,1964;Wilde, 1965; 1 29 and Menard, Smith and Pratt, 1965). A high quantity of sandstone in the channel facies is reported in probable fossil deep-sea fans (Bartow, 1966; Walker, 1966).In both the rocks and the recent sediments investigators found that the channels are flanked by clays with silt laminae.From a diving saucer in La Jolla Channel off California, Moore (1965) observed that the walls of the channel are cut into clays containing laminated silts.Interchannel regions in these areas, as in Astoria Fan, typically have less coarse material, fewer coarse layers, and thinner coarse beds. Proximal to distal stratigraphic changes in Astoria Fan do vary in some respects from the proximal to distal changes reported in similar environments.Numerous, coarse, and thick late glacial beds are found in the interchannel regions of lower Astoria Fan (Figure 10; Table 8; Appendix 11).A gradation to thinner and finer coarse layers with a high mica content is noted on lower Monterey Fan (Wilde, 1965).Walker (1967) also observed thinner and finer beds in the distal portion of paleo-ba sins.In tracing individual Mazama ash layers nearly 160 km down Astoria Channel little or no change in thickness was noted (Table 8; Figure 28; Appendix 8': 205, 207, 376, 297298, 371, 391).Since late glacial deposits have not been found in the upper channels of Astoria Fan, it is impossible to determine whether similar lower fan deposits may be thinner and finer than comparable upper fan beds. 1 30

Some trends in postglacial coarse layers from the main channels correspond with Walker's (1967) findings.Thick gravel beds are found in the upper channels of Astoria Fan while silt layers are found in the lower channels.In all the interchannel areas, coarse interbeds are few in number and fine-sized in the postglacial sediments. The aforementioned comparisons emphasize that the importance of channels and of changing sedimentation regimes with time must be considered in the proximal-distal comparisons.The content of coarse material remains high throughout the channels, while laterally from the channel it decreases suddenly. When numerous, large density flows are occurring, much coarse material will be funneled through the channels to the middle and lower fan.Despite these complications, when the characteristics A-I from Table 10 are compared with a similar table compiled from numerous investi- gations of rocks (Walker, 1967, p.32), the trends away from the sediment source are quite similar. I 31

VII.SOURCE OF SEDIMENTS

Terrigenous Materials

The Columbia River, which discharges over 60 percent of the runoff of the Pacific Northwest (Highsmith, 1962), is the most likely source of the terrigenous materials in the Astoria Canyon and Fan regions.The present sediments of the Columbia River and the glacial and postglacial sediments of Astoria Canyon and Fan have the same clay mineral suites (Russell, 1967).The light minerals of the sands and coarse and medium silts in the Columbia River, Astoria Canyon, and Astoria Fan also have a similar composition (Table 11; Figure 17).All of these sediments are characterized by. a high quantity of rock fragments, low ratios of quartz :feldspar and quartz:feldspar plus rock fragments,andhave quartz > plgioclase > k-feldspar (Whetten, 1966). Heavy mineral content also indicates that the Columbia River is the source of material in the coarse layers of Astoria Canyon and Fan (Table .lZb).This writer and all investigators of sediments in and near the Columbia River find high percentages of opaque minerals, pyroxenes more abundant than amphiboles, and generally the clinopyroxenes more abundant than orthopyroxenes (Royce, 1964; Runge, 1966; Carlson, 1967). The data of Runge(1966), Carlson(1967), andthis author's study are the most consitent(Table 11); these analyses were Table 11. Summary of Light Mineral Analyses (Percentage by Number) Grain Quartz K-feldspar 1/ Carbon- K-feld- Plagio-K-rockCa-rockTotal Quartz Feldspar plagioclase ** Matrix' Sand rto ate** Quartz spars clase Frag. Frag. Rx Frag.Feldspar +Rx Frag ratio

Astoria Fan (Nelson) Maximum 98.3 98.0 9.9 46.7 20 30 17 22 68 2.5 .87 .7 Minimum 7.3 .11 2.3 15.5 7 4 0 0.6 19 0.7 .19 1.7 Mode* 50-80 1.5-19 5-7 25-35 10-15 15-25 <5 <5 30-50 .8-1. 1 0.3-0.5 .6-. 7 Upper 1.7 30 13 12 47 1.2 .4 1.1 Middle 9 0 30 13 20 37 0.9 .4 0. 7 Lower 3.8 33 14 19 34 1.0 .5 0.7 Average 4.8 31 13 17 39 1.0 .4 0.8

Astoria Canyon (Carison, 1967) 2.9 26 9 20 44 0.9 .4 0.5

Columbia River (Whetten, 1966)

McNary 47 11 15 27 1. 8 1. 1 0. 7 Dalles 26 9 14 51 1.1 .4 0.6 Bonneville 38 11 16 35 1.5 .6 0.7 Average 37 10 15 38 1.5 .6 0.7

* two-thirds of samples in this range

percent by weight

matrix = <20u size material grain - > 20u size material N.) Table 12aSummary of Astoria Fan Heavy Mineral Analyses (Percentage by Number). Rx *** Heavy frag. 1g. Meta. Ortfio- Clino-Gar- Epid- zircon andal ica Location Sand Mm. &weath Opaquesamph. amph. pyrox. pyrox. net ote apatite usite

Astoria Fan (Nelson) Max. 85 35 37 49 20 7.2 21 39 4.7 5.9 62 8 94 Mm. 0.1 0.8 1 1.4 1.4 0.0 1 1 0.0 0.0 0.0 0.0 0.0 Mode* 25-85 1-5 10-30 10-20 10-20 1 5-15 15-25 1-2 1-2 1-3 1-2 0-8

Table 12b. Pyroxene/Amphibole Ratios for Sediments of Astoria Fan and Adjacent Areas (Percentage by Number) Pyr oxenes/ Location Amphiboles Pyroxenes Amphiboles Astoria Fan 15 30 2.0 Astoria Canyn 18 22 1.2 (Carison, 1967) Wiflapa Canyon 4 10 2. 5 (Royce, 1964) Continental Shelf 17 25 1. 5 (off Columbia) (Runge, 1966) Columbia River 14 38 2.7 (1.9mi. from mouth) (Howell, ** 1966) *two-thirds of samples in this range **Unpublished data, U. S. Army Corps of Engineers, Portland, Oregon ***percentage by weight mm. = minerals, Rx. frag. and weath = rock fragments and weathered grains, 1g. amph. = igneous amphiboles, Meta. amph. = metamorphic amphiboles, pyrox. = pyroxene. 134 completed in the same laboratory using similar procedures. The petrology of rock fragments, presence of yellow grains, and high quantity of mica in sediments from the Columbia River, nearby continental shelf, and coarse layers of Astoria Fan again indicate that the Columbia River and adjacent shelf have been the source of sediments for the coarse layers of the fan (Whetten,1965;

Runge,1966). The rock fragments in the Columbia River and the coarse layers of the fan are largely basalt and andesite (Whetten,

1966). Usually, sands of the inner shelf and the deep-sea fan off Oregon include "yellow grains" that in order of decreasing abundance consist of weathered feldspar, chert, volcanic rock, and other altered particles (Kuim,1965;Maloney,1965;Runge,1966;Ap- pendix 3).On the central shelf, Maloney(1965)found that "yellow grains" decrease in size and abundance to a depth of50fathoms and are absent byond; in the northern and southern regions of the shelf the "yellow grains" are not present beyond 30 to 40 fathoms depth

(Runge,1966). The occurrence of "yellow grains" thus suggests that the coarse fan sediment comes from the shelf. The texture, as well as mineralogy, of the lower Columbia River and northern shelf sediments is like that of the average coarse sediments of Astoria Fan (Runge,1966;Whetten, 1966; Bonneville Dam; Figure 17B).The greatest similarities of texture are between sediments of the northern shelf and sands of the Bonneville Reservoir, 135 and between coarse layers of the fan and sediments of the outer shelf and upper slope off the Columbia River (Runge,1966;Whetten,1966). These data suggest that outer shelf sediments derived from the Columbia River were the immediate source of coarse layer material of the fan. The near shore source of plant fragments and terrigenous source of pollen is substantiated in surface sediments by their gradient to higher content toward the land mass (Figures 18 and 20). Since the pollen grains are mainly coniferous, there is no question that their source is forests of the continent (Appendix 4).The plant fragments appear to be parts of algalstipes and blades.The algae probably has been broken up by wave action along the coast and then carried offshore by currents.

PlanktonicOrganism Remains

Single-celled planktonic organisms are the source of many of the fossil remains of the sediments.In the surface postglacial sediments the radiolarian tests become more common toward the open ocean and the diatom frustules become more abundant on the continental terrace (Maloney,1965;Carlson,1967;Figures 18 and 21; Appendix 3).Near the continent a high content of terrigenous debris may mask radiolarian abundance.However, changing ratios of radiolarians to diatoms from the continental terrace to the open 1 36 ocean indicates that the production of radiolarians increases away from the continental terrace (Figure Zi).Because radiolarians live throughout the water column, the greater productivity of radiolarians offshore may be explained by the increasing water depths.The increase in diatoms toward shore may be because primary producers have their greatest production nearshore where there are abundant nutrients from land surface drainage and upwelling. Pl3nktonic foraminifera are the source of calcaceous tests that are the predominant biogenous constituent of late glacial sediments. The cause of the faunal change from glacial to postglacial sediments is probably linked to the climatic changes between the two periods. No gradients of quantity of foraminiferal tests offshore were ascer- tamed.This may be due to the increased coarseness and detrital constituents of glacial compared to postglacial clays.The masking of planktonic material by terrigenous debris was greater during the late glacial period because the source of fine, terrigenous debris was larger and closer than for the postglacial period (Figures 15 and

18).

Benthic Organism Remains

Remains of benthic organisms in the sediments of Astoria Fan have a patchy distribution which indicates that the source, the living benthos, also must be grouped in its distribution.For example, 1 37 when the coarse fraction of a layer has a high quantity of sponge spicules, visual inspection of the sediment reveals clusters of Bathysiphon sp. which build their tests of spicules.Intermittently, masses of fecal pellets, worm burrows, and echinoid spines have been observed in the clays.Benthic material of the coarse layers is primarily from shallow water origin.Occasionally, remains of shallow water clams are found, and commonly, displaced benthic foraminifera occur.

Authigenic Materials

Pyrite and glauconite in the coarse fraction of sediments seem to derive from diverse sources.Glauconite is not found in clays and occurs only as scattered grains in the coarse layers.Apparently, it is displaced with other coarse layer materials, such as benthicfora- minifera, from the glauconite.rich regions of the upper slope and outer shelf that surround Astoria Canyon (Runge, 1966; Carlson,

1967).Some pyrite in the coarse layers of the fan may be detrital, but in general it seems to have formed in situ in association with organic material.The most common form of pyrite is botryoidal masses; these were found separately in the sediments and associated with organic matter.Very, often planktonic foraminiferal tests are filled with grape-like masses of pyrite. 1 38

VIIL SEDIMENTARY PROCESSES

Hemipelagic Sedimentation

Lithology, composition, and texture of olive gray and gray silty clays substantiate that they have been laid down by continuous particle by particle deposition of materials that have filtered slowly through the water column.These fine-.grained beds, although dominated by planktonic constituents in the coarse fraction, are composed pri. manly of terrigenous clay derived from the continent (Russell1967); therefore, these are hemipelagic sediments. The lateral gradation of composition and texture in the clays across the fan helps to differentiate sedimentary processes aswell as sources.Since coniferous forests cover the Coast Range and this coniferous pollen is transported the greatest distances by wind, the general decrease in abundance of coniferous pollen offshore may be significant.This gradation suggests that some of the hernipelagic materials are carried seaward in diminishing amounts by winds off the continent (Figure 18).The high content and composition of clay show that a great deal of the heniipelagic material is introduced by the Columbia River (Russell, 1967).Decreasing amounts of plant fragments, detrital materials, and silt offshore suggest that these materials are carried from the near shore region by the high wave and current energy. As nearshore current and wave action decreases 139 toward the open ocean, the terrigenous constituents settle from the water column (Figures 18 and 20).While the coarse terrigenous debris decreases offshore, the contribution of planktonic materials from autochthonous production and of clays from diffusion of finer and finer material away from the continent becomes relatively more important (Figures 18 and 21). Olive gray and gray silty clays in Astoria Canyon and Fan (Carlson, 1967), and the "continuous" deposits (Gorsline and Emery, 1957) and "muds" (Shepard and Einsele, 1962) of the Continental Borderland off California, are all beds of normal, hemipelagic sedimentation.These continuous deposits are disrupted by coarse materials that are exotic to the normal deep-sea environment and that are deposited by intermittent events of sedimentation.

Transportation and Deposition of Exotic Materials

Ice-rafting

The gray silty clay with pebbles has the lithologic, textural and compositional characteristics of sediments with ice-rafted glacial debris. Very poor sorting is the classic textural parameter that typifies deposits with glacial debris.Even without the pebbles the pebble clay has the poorest sorting of any clay lithology; with the pebbles it would have the poorest sorting of any sediment on the fan (Figure 12). 140

Rounded basalt pebbles in the clay provide evidence ofglacial and probable ice-rafting processes. One pebble in coreD-2 was found with silt laminae below bowing around thepebble (Figure 8E). Silt laminae above the pebble were flat-lying,indicating that corn- pression had not caused bowing of the laminabelow the pebble.It appears that the pebble dropped into theclay of the deep sea causing the pre-existing lamina to bend beneath the pebble.Since some of the pebbles have striations, the logical inferenceis that the coarse material has been transported and deposited byice-rafting. Ice-rafted sediments of the Northeast Pacific,whose distribution extends to just north of the area of this study,have a distinctive coarse fraction of detrital minerals(Hurley, 1960).Since other clays of the fan have a biogenous coarse fraction,the terrigenous (detrital minerals) composition of the coarsefraction of the clay with pebbles again suggests glacial origin and ice-raftingsedimentary processes.Discovery of glacial sediment in the region ofAstoria Fan extends the area of ice-rafted glacialdebris about ZZ0 km south of its previously known extent (Menard, 1952).

Sediment Slumping

Some of the sediments of the fan near thecontinental slope and mouth of Astoria Canyon have traveled only a veryshort distance after slumping off the canyon walls or thecontinental slope.There 141 is abundant evidence for slumping in lower Astoria Canyon (Carison,

1967).Sediments near the canyon walls have overturned, doubled, and reversed stratigraphic sequences of Pleistocene and postglacial sediments.Precision Depth Recorder traces from the base of the canyon walls show apparent slump blocks.The very poor sorting of some coarse sediments also is typical for slumped material (Kuenen and Menard, 1952). The very poor sorting, high clay content with gravels, and positive skewness show a lack of current transport of the upper fan coarse layers near the head of Astoria Channel and the Slopease Fan Valley (Figures 11 and 13).Location of these beds near the base of the continental slope, incorporated material from the upper slope (benthic foraminifera, glauconite, mineral suites), and textural characteristics indicate that this material slumped from the outer shelf-upper slope region.Apparently, these thick, coarse, unsorted, generally structureless, and ungraded beds have been transported only a short distance and deposited by sedimentary processes transitional between slumping or sliding and well developed density currents (Figure:8F and 8H).The succeeding discussion substantiates that the coarse material has been distributed and deposited throughout the fan from density currents that probably were generated by slumps. 142

Density Currents6

Evidence of the source of coarse materials from the Columbia River and adjacent shelf and slope, of slumping from the canyon and slope walls, of physiography, of stratigraphy, and of lithology, texture, composition, and sedimentary structures within the sediments of the fan indicates that density currents have been an important sedimentary process building Astoria Fan. Light and heavy mineral analyses, and benthic foraminiferal studies reveal that the coarse layers of Astoria. Fan have the same mineral and faunal suites as the sands of the continental shelf and upper slope near the Columbia River (Tables 11 and 12; Appendix 9). The presence of. 'yellow grains?? and detrital glauconite also helps to verify the upper slope and shelf source of coarse layer materials. Textural grading, one of the best criteria for deposition by density currents, is present (Kuenen, 1964).In addition to texture, composition of coarse layers on Astoria Fan has pronounced grading (Table 9).The coarse layers have sand-size light and heavy minerals concentrated at the base and clay, mica, plant fragments, and volcanic glass concentrated at the top (Appendix 10; Figure 21).

6Densitycurrents in this study are considered to be turbulent mixtures of water and suspended sediment in the deep sea that move as a unit through the surrounding water mass because of density differences that may be large or small. 143 Positive skewness of Astoria Fan coarse layers supports a hypothesis of emplacement by density currents (Ericson, etal.

1961).In shallow water environments negative skewness seems to indicate tractive current winnowing (Duane, 1964).The positive skewness of coarse layers of Astoria Fan thus suggests that tractive current winnowing from ocean bottom currents did not form the coarse layers. Lamination, cross..lamination, cut and fill structures, and convolute lamination are common in the coarse layers of Astoria Fan; they also are common in other deposits of density currents (Kuenen, 1964; Bouma, 1962).Bouma's (1962) complete sequence of sedimentary structures for turbidites is noted in some layers (Figures

23 and 24).Parts of this sequence and Kuenen's (1964) normal structuring for density current beds are seen in nearlyallAstoria Fan coarse layers. Fan physiography, channel and interchannel stratigraphy, and sediment facies grading downslope from the mouth of Astoria Canyon indicate that density currents have funneled out from the canyon mouth.Channel morphology and restriction of the coarsest material to channels indicate that currents depositing coarse layers have been channelized from the canyon mouth; they have not operated like normal, widespread bottom currents.The deep, narrow channels with coarse, unsorted deposits on the steep upper fan break into 144 low-banked distributaries with sorted deposits at the change in slope on the middle fan.This also suggests that flow of materials has been facilitated by density currents down the fan gradient. Details of stratigraphy and lithology of ash layers provide evidence that layers were emplaced by density currents.Tuffaceous sand layers at the mouth of Astoria Canyon are the thickest (>50 cm) and coarsest in the area studied (Figure 10; core D-10); they contain pumice fragments of pebble size (Figure 8F).In Astoria Channel the ash is found in two closely-spaced layers of tuffaceous sand or silt 10 to> 30 cm thick (Figures 10 and 28).The lower layer is thicker and contains more glass than the upper one; both layers are graded and ash is more abundant in the upper portions of both layers (Figures 10, 25, 28, 30; Appendices 8 and 10; Samples 203-207, 374-379, 369, 371, 372).In the interchannel areas of Astoria Far, one and occasionally two closely-spaced ash layers may bepresent midway in the upper meter of sediment (Figures 10, cores A-2, E-3,

D-3, A-3-2, B-4; 28; 30, core no.3).Interchannel ash layers generally are a few centirneters.thick and contain a higher quantity of glass than do the ash layers in the channels of the fan (Figures 10, cores A-2, E-3, D-3, A-3-2, B-4; 28,30, core no.3). The heavy mineral assemblage of the ash deposits includes most of the minerals found in the Mazama ash as well as many other minerals not associated with the Mazama suite (Wilcox, 1966).The 145 heavy and light mineral assemblages in the tuffaceous coarse layers are most typical of the Columbia River drainage (Appendices 6 and 7, samples 196-207). In addition to the foreign heavy minerals and generally appre- ciable quantities of other detrital minerals, most ash layers contain displaced shallow water benthonic foraminifera and plant fragments (Appendices 9, sample 194; 10, samples 203-207, 374-379, 369, 371, 372).These contaminants ,together with the grading of texture and ash content from nearly all detrital and < five percent ash at the base to > 70 percent glass at the top of some layers (Figures 25 and 28 ), indicate that the volcanic glass slumped with debris from the continental shelf and slope and was carried to the sea floor by density currents.The minor amounts of ash in the interbedded hemipelagic sediments (Appendix 3) also suggest that most of the Mazama volcanic glass was deposited by density current flows with a high quantity of ash debris rather than as direct air fall of pyroclastics. The continental distribution of Mazama ash shows that the oceanic area is west of the pyroclastic fallout from the Mazama eruption but that large quantities of ash blanketed the Columbia River and coastal drainages (Figure 29 inset).Soon after the eruption, a great quantity of ash and pumice must have been carried seaward to the continental shelf where it either dropped out of suspension or was carried out to sea in suspension, depending upon the grain size 146 of the material. Because of the size of the Columbia drainage, its location with respect to the continental ash fall, and the concentration and thick-. ness o f a s h on Astoria Fan, it appears that the bulk of the volcanic glass deposited in the marine environment was derived from the Columbia River drainage.The occurrence of the thickest ash layers at the mouth of Astoria Canyon and down Astoria Channel, and presence of upper slope and outer shelf fauna in these layers suggest that ash accumulated at the head of Astoria Canyon and then traveled through the canyon and Astoria Channel.Near shore drift of the ash, at a time when sea level was lower and the shoreline was displaced farther out on the continental shelf, probably aided the accumulation of debris at the head of the canyon.Furthermore, channels con- necting the mouth of the Columbia River to the head of Astoria Can- yon (Berg, King, and Carlson, 1966) may have been in existence when the initial ash deposits were carried down the river. Ash probably accumulated rapidly in the head of Astoria Canyon; it became unstable and slumped down the axis of the canyon onto Astoria Fan and into Astoria Channel as density-current flows.The presence of the two ash layers separated by hemipelagic clay indicates at least two major flows down Astoria Channel.Radiocarbon dates and lack of ash layers above the one or two closely-spaced layers of Astoria Fan and Channel indicate that most of the material was 147 carried down the Columbia River over a short time interval (Figure 30). The presence of thick, tuffaceous layers of sand and silt throughout Astoria Channel indicates that the main part of a density current flows in the fan channels and deposits material that varies little in grain size, composition, and character for long distances

(Figures 10, cores D-10, 65-5, 65-4; 28,29),The correlative sequence of thin, vitric layers of fine silt in the interchannel regions of Astoria Fan suggests that fine material from a density current flows throughout interchannel areas, but does not travel as far from the source as the coarse material in the channels (Figures 10, cores A-2, E-3, D-3, A-3-2, B.-4; 28,29,30).The interchannel ash layers and upper portions of the channel ash layers contain high concentrations of plant fragments, mica, and ash, possess fine grain size, and lack heavy minerals (Figures 25,28, 30; Appendices

8,10).These characteristics seem to develop because the less dense material lags behind and diffuses above and laterally out from the main density-current flow of the channel. Distribution of Mt. Mazama ash seems to verify that the clayey silts are fine materials deposited from the density-current tail or clouds of fine debris that spread beyond the channeled part of the flow.The interchannel clayey silt deposits have the same textural and compositional characteristics as the upper parts of the 148

coarse layer sequences (Figure 28).Displaced foraniinifera, corn- mon in clayey silts, support this interpretation. The size of the density currents of Mazama ash can be specu- lated upon since the ash deposits can be traced so well.To carry ash from Astoria Canyon throughout the interchannel regions of the upper fan, the density currents apparently were thick enough to spread beyond upper Astoria Channel which has nearly 100 fathoms of relief,On Astoria Fan the volume of sediment that contains significant amounts of ash can be estimated from the area that the tuf-

faceous deposits cover (7 x km2)and fromtheaverage thickness of layers (Figure 28).A computed volume of 2. 5, x 1053rn of tu- faceous material falls within Menard's (1964) range of estimates of the size of slumps(104m3to 7 x1010m3)that generate density currents.The size and amount of material deposited in channel and interchannel regions indicate that flows must have a relatively high density in the channels and much lower density in interchannel regions.The average of the tuffaceous layer thickness through the channel cross-section area gives an estimated flow excess density of about . 001 gm/cc in the upper channel.Undoubtedly, most of the coarser material was transported near the sediment-water interface and the density was much greater in this region. Textural changes reveal other mechanisms of density currents on Astoria Fan.The change in sorting and clay content of coarse 149 layers down the channels and the fan indicates that the increase jn clay occurs during the formation and early movement of density cur'. rents; shelf sediments and lower fan coarse layers with a comparable phi mean diameter have less clay and are better sorted that upper fan layers (Runge, 1966; Figures 11, 14, 22).When the density current moves away from the source, the fines apparently spread outbeyond the channel and the coarse channel material progressively loses its clay down the channel (Runge, 1966; Figures 11,14, 22), Compositional changes of benthic foraminifera in the layers provide additional evidence on desnity-current processes.The foraminiferal suites in relatively thin coarse layers are from a restricted depth zonation suggesting that slumps occur from specific depths, particularly for the smaller density currents.Foramini- feral suites in. the thickest layers have great variation, which mdi- cates that the large slumps incorporate material ovez a wide range of depths (Figure 25: 351-355; Appendix 9).Natland (1963) made a similar finding in rocks, namely that foraminifera are picked up throughout the path of a density current.Only shelf species are found in the cleanest sand at the base of one of the thickest coarse layers of the fan (Appendix 9:355). Above the basal portion of the layer a mixed assemblage of benthic foraminifera occurs from all depths, and in the finest portion of the upper layer only small- sized species occur.Similar observations have been made by other 150 investigators (Natland, 1963; Holterdahl, 1965; Table 9).The faunal distribution indicates that the coarsest material, shelf sand, stays intact at the base and head of the density current.Foramini- fera from all depths are mixed and carried in the intermediate-sized portion of the density current.The fine tail of the density current appears to sort and carry the small-sized foraminifera just as it sorts and carries the most current-sensitive platy-terrigenous materials.This model of a density-current process conforms with one of the early classic descriptions of turbidity currents having a uni- form head of coarse sedinients and a tail of fine materials (Kuenen and Menard, 1952). Although competence and sorting appear to be maintained for great distances down the channel, the heavy mineral content in the basal portion of the sands decreases slightly downchannel (Figure 22;

Appendix 10).Wilde (1965) made a similar finding on Monterey Fan,

Summary of Density-Current Processes

Distribution of tuffaceous deposits and stratigraphy of coarse layers in the fan valleys and of clays with silt laminae in the interchannel regions of the upper fan imply that the coarsest material of density currents flows through the channels while the fine debris billows above and beyond to the interchannel regions.Th&s cloud of fine debris, the density-current "tail, "is deposited as clayey silts 151 above the main coarse layer and in the interchannel regions. On the middle and lower fan the many shallow fan valleys with low levees and numerous coarse layers throughout the section suggest that density currents divide into subflows that travel through ephemeral distributary systems. Ash distribution on the lower fan shows that individual flows may not spread widely; however, the channels probably shift often because of low levees, the tendency for the "hook to the left " (ivlenard, 1955), and rapid channel filling. Thus, a stratigraphy of clay and thick, coarse interbeds develops throughout the lower and middle fan.

Other Sedimentary Processes

Ocean Bottom Currents

Recently, investigators have hypothesized that ocean bottom currents which carry bed load by traction are important in the cle- position of deep-sea coarse layers (Hubert, 1964; Heezen and Holl&ster, 1964a; Heezen, Hollister, and Ruddiman, 1966).The evidence from this study does not substantiate such bottom current activity on Astoria Fan.Cross-lamination would be expected from the top to the bottom of the layer if bottom currents are the cause; where present, cross-lamination seldom occurs at the top and usually occurs near the middle of the bed.Bottom currents should 152 winnow fine-sized materials from the normal sediments and concen- trate planktonic constituents in the coarse layers (Shepard and Einsele, 1962).Thousands of coarse layers of Astoria Fan were examined, but only one bed contained concentrations of planktonic material; these were laminations of planktonic foraminifera.Win- nowing by tractive bottom currents in shallow water results in a negative skewness (Duane, 1964).All the coarse layers of Astoria Fan possess a positive skewness that suggests density-currenl deposition rather than tractive bottom currents (Ericson, etal. ,1961). Lithologic, stratigraphic, and physiographic evidence shows that currents depositing the coarse layers are restricted mainly to channels, are variable in velocity, are sporadic in occurrence, and generally have not been present since the Mt. Mazama eruption 6600 years ago.Normal tractive bottom currents from geostrophic flow conditions, thermohaline circulation, and tidal variations would provide a more regular, widespread flow.These currents would not develop gradient-affected channel, levee, and distributary systems that are observed on Astoria Fan.Normal bottom current activity, although possibly altered by circulation changes at the end of the ice age, is not likely to have changed from deposition of numerous coarse layers up to gravel size in glacial periods, to termination of all coarse layer sedimentation in the late postglacial period.The general lack of coarse layers in the post-Mazama 153 postglacial sediments signifies that the bottom current activity on the fan now is limited to currents too weak to deposit coarse jayers. Concentration of platy materials in clayey silts and deposition of these layers may be evidence of bottom current activity,How- ever, other evidence indicates that density currents are the most likely explanation.Even gravel layers of the channels grade to high concentrations of platy materials in their upper portions.This indicates a very large, rapid, and irregular change in curreit velocity that would not be typical of bottom currents.Similar, rapid velocity changes in depositional currents are indicated by the apparent contemporaneous sedimentation of pumiceous gravels in channels and tuffaceous clayey silts on levees alongside (Figure 1O cores D-1O, E-3).Deposition of tuffaceous and other silty clays in levee and interchannel areas simultaneously with channel coarse layers seems best explained by spread of theutail?!of fine sediments from the main density-current flow in the channels. Some evidence used to support the hypothesis of bottom current deposition of deep-sea coarse layers does not appear to be valid. Examination of bottom current data reveals that the high deep-sea velocities reported by several authors (Hubert, 1964; Heezen and Hollister, 1964a) have not been found within five meters of the sea floor (Table 1).Sinusoidal trends in plots of sorting vs. mean size and skewness vs. mean size (Folk and Ward, 1957) have been 154 reported for shallow and deep water sands by Hubert (1964).Be- cause of this similarity, Hubert (1964) postulated that the same trc- tive current origin of shallow sands was applicable for the deep-sea coarse layers.However, sinusoidal trends seem to be inherent in the plots of statistical parameters for any sediments (Folk and Ward, 1957).Plots of hundreds of sediment samples off Oregon from the beaches, continental shelf, continental slope, and deep-sea floor all have sinusoidal trends (Runge, 1966; Carison, 1967; Figures 11,

12,13).It appears that no environmental significance can be attached to the sinusoidal curves. Hubert (1964) also believed that a low percentage of clay in the coarse layers was evidence of deposition by bottom currents. In this study, however, a low content of clay is found in tuffaceous layers of established density-current origin (Appendix 8 ).Change from upper fan to middle and lower fan type coarse layers on Astoria Fan also shows that there is a trend to less clay from the near- source to the distal regions (Figures 14 and 22).As the density current progresses away from the source on Astoria Fan, fine materials apparently billow out from the density-current head, trail behind and spread out from the coarsest material in the channel.Conse- quently, the percentage of clay may be very low in the coarse part of any density-current deposit at distance from the source.This finding undermines Hubert's (1964) hypothesis that a low percentage 155 of clay reflects deposition by tractive bottom currents. Lamination and cross-bedding have been cited as evidence for deposition by ocean bottom tractive currents (Hubert, 1964; Heezen and Hollister, 1964a).Recent experiments by Kuenen (1965) and sedimentary structures of Astoria Fan suggest that lamination and cross-bedding are just as indicative of density current deposits as of tractive current deposits.

Sediment Creeps Sand Flow, Vertical Density Currents, and Seismic Sea Wave. and Surface Currents

Sorting and grading characteristics of coarse layers indicate that sediment creep and sand flow have not been important sedimentary processes on Astoria Fan.The low gradient over the fan and distance from steep slopes, except near the continental slope, also make it unlikely that sand flow or creep have been transporting agents. Vertical density currents have been proposed for deposition of pyroclastic ash fall into the water (Bradley, 1966).The evidence from Astoria Fan indicates that horizontal density currents along the sea floor distributed and deposited the ash there. Seismic sea waves are prevalent in the Northeast Pacific, but their effect on sediment transport is unknown.Similar characteristics of coarse layers on Astoria Fan and in other sedimentary 156 environments without seismic sea waves, such as Crater Lake, suggest that the effect is not detectable (Nelson, 1967).General lack of coarse layers in the post-Mazama postglacial sediments of Astoria Fan, when historical seismic sea wave currents occurred, also substantiate this view. Surface currents are important for distribution of suspended fine sediments.This process is verified by sediment masking of pelagic materials on and near the continental terrace and by gradations of terrigenous and pelagic debris out from the shore (Figures 1821).The increase in pelagic materials and decrease in tern- genous debris to a point of stabilized content midway on the fan may be related to surface currents and distribution of the materials of the Columbia River plume.Earlier discussion of oceanographic setting revealed that surface currents and consequently, plume movement parallels the coast for several hundred kilometers.The plume extends offshore only about 200 km. As a result, the north to south boundary of the end of gradation of surface sediment composition approximately coincides with the western limit of the plume; this may explain why hemipelagic composition trends parallel the coastline rather than the shape of the fan. 157

IX.RATES OF DEPOSITION

General

Data. from ash, faunal, and lithologic horizons, and radiocarbon dating of sediments from adjacent regi.ons are available for estimating the sedimentation rates on Astoria Fan (Figures 27, 30,;31;

Table 13; Appendices 5,12). Some variance of sedimentation rates is found from core to core and within a single core when different data are used (Appendix

12).These apparent differences may be caused by factors of faunal and stratigraphic transition, of coring anomalies, and of sedimentary processes.Because of faunal transition, it is sometimes difficult to select a definite depth for change from glacial to postglacial sedi- merits on the basis of fauna.The onset of pelagic sedimentation above each density current bed also can be difficult to determine because of the transitional nature of sedimentary deposits.Coarse layers grade from clayey silt tails into pelagic sediments and no sharp beginning of pelagic sedimentation can be ascertained unless a continuous analysis of sediments above each bed is made.Be- cause this is not practical, change is estimated by observing xnega- scopic lithology.This may result in slightly high estimates of pelagic sedimentation rates since clayey silt sediments sometimes have the appearance of hemipelagic clay lithology and may be 158

TOTAL SFDIMFNTATION RATFS OF POSTGLACIAL (CM/1O3yr) I I I I I I 1 127°00' 12600 1400 1300 200 1100 000

22" j ()* i) 8 C 'd 32. * 4 .1' / N 7 ( 6 k.

12* L2

\ 1550 #4 L 45 00'

C..)

: :(

ASTOR/A -.. ," PAN 300 t5-R5diocarbon Data (Pculm and Grig9s.1966) 111400 K (1500 1550 J) 2J0 Piston Core and Phleger Core sample station ? NAUTICALMILES Contour Interval 100 fathoms 8Faunal Data ------50fathoms 0 10 20 Data KILOMETERS Compiled by lions Nelson

Core anomaly - did not penetrat. glacial Clay, port Ion of core it,-eched, or portion of core lost.

Figure 31.Sedimentation rates of Astoria Fan.All rates are total rates of deposition. Table 13.Summary of Sedimentation Rates on Astoria Fan(cm/lU3yrs)

Total rate Rate pelagic Total rate Total rate post-glacial Rate pelagic Rate pelagic clay post- post-glacial post Mt. to Mt. clay on post- clay postglacial to Cores faunal change- Mazama ash Mazama event glacial faunal Mt. Mazama ash Mt. Mazania

Interchannel

Upperfan 8.4 11.3 6.1 7.9 9.9 6.5

Middle fan 7.8 9.0 7.2 7.3 7.8 5.4

Lowerfan 7.7 7.4

All 8.0 10.2 6.7 7.5 8.9 6.0

* Channel

Upperfan 25.0 13.0

Middle fan 17.0 16.5 22.2 15.0 13,0 18,7

Lowerfan 33.0 23,0 45.4 21.5 18,0 30,4

All 25.0 21,5 33.8 18.3 14.7 24.6

* any postglacial rate is the minimum estimate since complete transition to glacialsediments was neverpenetrated in main channels.

change from radiolarian to foraminifera fauna as datum lowest Mt. Mazama ash layer as datum ash and faunal datums clay layers only; thickness of coarse beds subtracted fromtotal thickness 160 included with them.Coring anomalies also affect the calculation of rates since sediment may be lost off the top or stretched in piston cores, and may be compressed in gravity cores.

Interchannel Regions

Postglacial rates of sedimentation in the interchannel regions of Astoria Fan are consistently lower than comparable rates in the channels(Table 13).Normally, the upper fan, which is nearest the main sediment sources, has the highest sedimentation rates and the lower fan has the lowest for any given time period.The rates of de-. position of postglacial pelagic clay and of the total column of postglacial sediments vary only slightly.The small variance is explained by the general lack of coarse layers in interchannel postglacial sediments. Rates of sedimentation for the pelagic clay and total sediment column in the interchannel regions are lowest in the early postglacial period (pre-Mt. Mazama event) and highest after the Mt. Mazama event.Most likely, this is due to the influx of ash and ash-induced slump sediments.The glass in olive gray clays above the ash hon.. zons and lack of shards below the tuffaceous layers exhibit this influence.Tuffaceous layers that average 4 cm thick cover

7 x103km3of the fan (Figures 28 and 29; Appendix 8).This volume of ash (2.8 x104km3)is only . 0005 percent of the volume of 161 pyroclastics (11 cu mi, Williams, 1942) estimated to have been ejected in the cataclysmic eruption of Mt. Mazarna. Quite likely, a greater volume than that observed in the visible tuffaceous coarse layers was carried to the sea.The volcanic glass of the coarse fraction (>62) of pelagic clays overlying the ash layers verifies this (Appendix 3).Since even visible ash layers are made up mainly of glass shards < 6 in size, it is likely that the quantity of ash in the fine size fraction of the late postglacial clays is much higher than that indicated by percentage in the coarse fraction.

Channels

All postglacial rates of sedimentation are nearly two to three times higher in the main fan valleys than in the interchannel regions. The greater size and frequency of density current flows in the channels than in the interchannel areas seem to be responsible for this difference.; however, the steep valley walls (Figures 4 and 6) also facilitate slumping and downslope gravitative transfer of material to fill the valley floors.Because of the density-current activity in channels, the differential between pelagic and total rates of sedimentation is greater in channels than it is in the interchannel regions.This density-current activity that was greater in the early postglacial period also may explain why the highest rates of sedi. mentation occurred in the channels during the early postglacial 162 period rather than in the later postglacial period (Figure 27).

Sedimentation Rates Compared with Other Regions

Sedimentation rates are higher in Astoria Canyon than they are on the fan (Carison, 1967; Table 14).In Astoria Channel just to the south of the fan, rates are similar to the channel on the fan (Duncan, 1968; Table 14).Rates for the canyon floor are much higher than they are in the inter-valley regions of Astoria Canyon; these differences in rates are comparable to those of the channel and interchannel regions of Astoria Fan.Cascadia Channel also has extremely high total postglacial rates of sedimentation that are greater than any similar rates encountered on the Ian (Figures 1 and 27; Table 14; Kulm and Nelson, 1967; Duncan, 1968).To the west of Astoria Fan in Cascadia Channel and TuftsAbyssal Plain, rates of pelagic sedimentation are much lower (Kuim and Nelson, 1967; Duncan, 1968; Figures 1 and 27; Table 14).These lower rates are attributed pri- manly to a greater distance from continental source oI clays. Hudson Fan, the continental borderland off Southern California, and Sigsbee Abyssal Plain off the Mississippi Delta have average total sedimentation rates near 10cm/103years for the postglacial (Table 14).When interchannel regions of the fan are considered, average total postglacial sedimentation rates for the fan are corn- parable to other, similar regions off North America. Table 14.Total Sedimentation Rates in Regions Near Astoria Fan and in Similar Marine Environments Rate Region Geologic Time (cm! years) Method Source

Astoria Channel (south of fan) Postglacial 27-32 Faunal Duncan (1968) Astoria Canyon mouth levee Postglacial 9 Mazama ash Carlson (1967) mouth Postglacial 53 Mazama ash Carlson (1967) head Postglacial 78 Mazama ash Carlson (1967) middle Postglacial 36 Radiocarbon= R. C. Carlson (1967) tributary Postglacial 12-19 Faunal, R. C,, ash Carison (1967) Cascadia Total ash, R. C. Klm and Griggs (1966) Channel Postglacial 15-100 Faunal Pelagic 1 West of fan Postglacialj 2 Faunal Kuim and Griggs (1966)

Depression Blanco Frac Zone Postglacial 300 Fai.mal Duncan(198)

Tufts Abyssal Plain Pelagic 2 Radiocarbon Nayudu (1964) ostglaciai _). uthem California Past 30, 000 10-30 Radiocarbon Gorsline et al. (1966) Borderland Gulf Mexico jgsbee Abyssal Plain Postglacial 10 Radiocarbon Heezen nd Hollister (1964) Hudson Fan Postglacial 8. 8 Radiocarbon Ericson et al. Cascadia Abyssal Plain Glacial 170 Radiocarbon Kuim and Nelson (1967) Tufts Abyssal Plain Glacial 10 Radiocarbon Nayudu (1964) Pelagic (only)) Sigsbee Abyssal Plain Glacial 59 Radiocarbon Heezen and Hollister (1964) 164

Sedimentation rates were much greater in the glacial than postglacial period for Astoria Fan as well as for nearby regions. On the fan, minimum late glacial rates of sedimentation of36to43 cm/lU3years canbe estimated from two types of evidence.Inter- glacial sediments of about 25, 000 to 27, 000 B. P., known to be present in this region (Nayudu,1964;Duncan, 1968), were not penetrated; however, 500 to600cm of late glacial clay beneath postglacial clay were sampled at many locations on the fan.If the interglacial sediments lay immediately below penetration by the corer, and the 500 to600cm of glacial clay represents about 13, 500 years of sedimentation(26, 000 B. P.interglacial-i 2,500 B. P. postglacial), then the minimum rate of sedimentation for the late glacial period

3 can be estimated at36to43cm/10 years.If the interglacial seth- ments lay far below the glacial sediments that were penetrated, the rates during glacial time were much greater than the minimum estimate given above. A sediment rate of 170cm/lU3years based on radiocarbon date on the western margin of Cascadia Abyssal Plain indicates that the minimum estimates for the fan are probably much lower than the true rates (Figure 27).The high rate on Cascadia Abyssal Plain was found in a nearby region that is farther from obvious sediment sources than is Astoria Fan. An increase in sedimentation rates of five to ten times from the postglacial to glacial period was postulated by Heezen and 165

Hollister (1964b).Nayudu (1964) reported glacial rates five times higher than postglacial rates in pelagic sediments of Tufts Abyssal Plain west of Astoria Fan and Cascadia Plain.Glacial rates six times higher than postglacial rates were noted by Heezen and Hollister (1964b) on Sigsbee Abyssal Plain in the Gulf of Mexico. They felt that glacial rates were much higher than this on the fan closer to the Mississippi River delta.In the tropical Atlantic Ocean, Broecker, Turekian, and Heezen (1958) observed that clay deposition was 3. 7 times greater and the rate of carbonate deposition 2. 1 times greater during thePleistocene.Since Astoria Fanis located much closer to sediment sources than open ocean areas with sedi-. mentation rates over five times greater in glacial periods, it appears that minimum estimates of glacial sedimentation rates of the fan are indeedvery low. Carbonate deposition in late glacial sediments off Oregon was increased in amounts similar to that noted in the Atlantic.The change in coarse fractionfrom up to 80 percent planktonic foraminifera in late glacial sediments to up to 80 percent radiolarians in postglacial sediments helps to account for the increase in carbonate deposition on Astoria Fan.In the same lithology and stratigraphy of adjacent regions, Carison (1967) and Kulm (1967) have measured changes from less than one percent carbonate in the postglacial to over two percent in the glacial sediments. 166

X.GEOLOGIC HISTORY OF ASTORIA FAN

History of the Region

A eugeosyncline has occupied the present Coast Range region since the Early Tertiary period (Snavely and Wagner,1964; Figure 1). After filling of the eugeosyncline by volcanics and immature sediments, an uplift began in late Pliocene.This eventually elevated the Coast Range and possibly the Oregon continental terrace. While the morphology of the continental edge was being altered, changes also were taking place in the adjacent deep sea because of the East Pacific Rise.The East Pacific Rise had its inception in the deep sea off Oregon beginning in the Early Tertiary (Menard,

1964)or Late Cretaceous (Vine,1966). This zone of high heat flow, raised topography, and active seismicity is thought to be the surface manifestation of the upwelled limb of convection cells in the mantle. Convection cells have been proposed by Hess (1962) to maintain "sea floor spreading. " Vine(1966)believed that paleomagnetic anomalies parallel to the crest of the rise indicate a rate of sea floor spreading from Juan de Fuca Ridge of 2.9cm/year for 5. 5 million years. Such movement may have provided the mechanism for forming the north-northwest ridges and troughs in the continental slope near the fan apex; it also may have been the force that folded, faulted, and uplifted Miocene and Pliocene rocks off the central Oregon shelf 167 region as much as 1000 meters (Byrne, Fowler, and Maloney,1966). This same uplift of late Pliocene occurred throughout the Coast

Range (Figure 1) on land (Snavely and Wagner,1964). Consequently, it may have raised the continental terrace in the Astoria Canyon region at the same time.The time of uplift suggests the possible age for the inception of Astoria Canyon, since the canyon probably would not have been incised through its apparent late Tertiary wall rocks before the present continental slope developed (Carlson,1967). Additional evidence indicates that the last significant uplift of the continental terrace adjacent to the fan and the consequent begin- riing of the Astoria Canyon-Fan system may have occurred during the Pliocene.The paleo-depths of Pliocene benthic foraminifera from outcrops of the canyon wall generally correspond to present day water depths (Fowler,1967). Any tectonism in the region since that time apparently has not been of significant magnitude to be distinguished on the basis of fauna (Carison, 1967).Plio-Pleisto- cene marine terrace heights of Oregon also support this hypothesis because they are much more pronounced along the southern than the northern coast.From north to south along the coast these discon. tinuous terraces generally are found at increasingly higher elevations

(Baldwin,1964). Age estimates of the fan, based upon glacial and postglacial rates of sedimentation and Columbia River sediment load, also suggest that deposition of unconsolidated fan sediments probably began after the late Pliocene uplift.These data will be discussed after the sequence of fan history has been related. Since the main history of Astoria Canyon and Fan appears to be linked to changes during the Pleistocene Epoch, review of the major post-Pliocene events is pertinent.One of these important alterations was the Pleistocene lowering o sea level up to an average of 72 fathoms (Shepard,1963). Buried channels in the present shelf off the Columbia River (Berg, King, and Carlson, 1966) may be old pathways through which the Columbia River flowed directly into Astoria Canyon during the low sea levels of the Pleistocene.At the times of lower sea levels, the canyon probably acted as a sediment trap for the longshore drift and sediment load of the Columbia River. The glacial sediments of Astoria Fan have an abundance of coarse layers with Columbia River material and upper slope to shelf fauna. This indicates that, periodically, the sediment slumped from the canyon and was carried throughout the fan by density currents. These apparent Pleistocene processes of the canyon-fan system probably are similar to those observed in modern canyon-fan systems in the Southern California continental borderland (Gorsline and

Emery,1959;Shepard and Einsele,1962;Chamberlain,1964; Dill,

1964). Pleistocene changes on land also affected sedimentation processes and increased the sediment load of the Columbia River. 169 Glacial erosion scoured debris, and meltwater runoff carried the sediment into the Columbia River.Ice damming and release of the meltwater in Lake Missoula caused catastrophic flooding in the Columbia River system (Bretz, Smith, and Neff, 1956).Uplifting and volcanic activity, which built the High Cascades during the Pleistocene, provided additional sediment. Postglacial events greatly affected sedimentation on Astoria Fan.The sea advanced, covered the continental shelf, buried the Columbia River channels, and developed the river estuary which now traps the coarse river sediment.Mt. Mazama in the High Cascades of southern Oregon had a cataclysmic eruption of pyroclastics 6, 600 years ago.This eruption showered the land surfaces of the Pacific Northwest and filled the river drainage with ash and plant debris.

Sequence of Events in Astoria Fan History

Late Glacial

Glacial ice-rafted sediments (gray silty clay with pebbles) of the Astoria Channel walls of the upper fan appear to be the oldest sediments encountered on the fan (Figures 2 and 10, cores D-Z, E-Z, and E-3).Glacial clay with pebbles occurs in the channel wall more than 150 m below the surface of the interchannel region (Figure 6);the c lay. is covered by three meters of late glacial density-current 170 sediments and then a meter of postglacial clay in the levee of Astoria Channel (Figures 2 and 10, coresD-2, E-Z, and E-3).Since glaciation on land extended to the Columbia River (Baldwin, 1964), it is logical that ice-rafted sediments may have been deposited on the fan by Pleistocene icebergs floating out from the COlumbia River. Possibly, the iceberg drift was mainly to the south from the Columbia River, since the ice-rafted sediments have been found only along the upper Astoria Channel.Present distribution of the Columbia River,plume water indicates that summer nearshore ocean currents carry the plume to the south.The summer thaw season with its high river flow is the most likely time during which icebergs would have been carried down the Columbia River.This hypothesis cannot be proven because few cores were taken to the north of the canyon mouth and these did not penetrate deep channel stratigraphy. The ice-rafted sediments may underlie all the upper fan and the current pattern may have been different in the Pleistocene.Also, there may have been other iceberg sources to the north. Deep fan valleys apparently were cut sometime after the deposition of the glacial clay with pebbles.Lack of density-current deposits overlying the pebble clays of Astoria Channel wall, and the presence of density-current deposits overlying glacial clay with pebbles of the levee of Astoria Channel show that this channel was scoured through the older glacial clay with pebbles.because glacial 171 sediments have not been encountered in the floors of the major channels, it appears that major channels are mainly erosional features developed during the regime of the intense density-current activity that took place in the Pleistocene. Physiographic evidence of ancient channel fragments that are steeper and elevated above present main channels suggests that the first main channels extended north from the region of the present mouth of Astoria Canyon (Table 3; Figure 7).In these older channels, gradients, minimum axial depths, and distance of channel fragment ends from the present canyon mouth seem to indicate that the main channels generally shifted successively further to the left and south through time.Eventually, they entrenched in the position of the present canyon mouth and the Astoria and the Slope Base Fan Val- leys.Smooth transition of axial gradients from the canyon into these channels and of gradients down channel implies that they have been the last active main channels.The distribution ç thic, tuffaceous coarse layers with Mazama ash in the upper Slope Base Fan V.11ey and down the entire length of Astoria Channel (Figure 27) substantiates this hypothesis.The lack of ash in the lower Slope Base Fan Valley suggests that this lower part with a raised gradient was structurally deformed prior to the Mt. Mazama event (Table 2). It appears that each fan valley system followed the same sequence of development. A deep, narrow channel was eroded in the 17Z upper fan and then divided into many distributaries with the change in gradient on the middle and lower fan (Figure 5).The gradual shift to the south, of fan valley systems may be explained by Menard's (1955; Menard, Smith, and Pratt, 1965) "left hook" theory.Because of coriollis force, material of density currents may tend to deposit

on the right levee of channels in the northern hemisphere.The buildup of right.hand deposits continually tends to divert channel flow and valley development to the left.The same history of change would seem to be even more true of the small distributaries on the middle and lower fan.The lower gradients, levees, axial depths, velocity, and relatively overloaded sediment load compared with steeper upper channels would make distributaries more susceptible to deposition and shifting than the deep channels of the upper fan. The high quantity of coarse layers throughout the interchannel regions of the middle and lower fan indicates that channeling has been widespread there. Comparison of sedimentary parameters of glacial with postglacial hemipelagic sediments substantiates the westward shift and lowering of the shoreline in the Pleistocene.The late iglacial gray silty clay of the lower fan has characteristics most similar to the postglacial clay near the continental slope (Figure 18).The gray clay is coarser and has a lower content of planktonic constituents than postglacial clays at the same distance from the slope (Figures 19, 173

20,71). Since the grading of surface sediment parameters with distance from the shoreline is known, the displacement of similar ratios of texture and coarse fraction of the late glacial clay compared with modern surface clay shows the direction of shift of the shoreline during glacial stages.The displacement of similar ratios permits the speculation of a late glacial shoreline position about 40 miles west of the present shoreline; this seems to agree with shelf- slope topographic break that has been suggested as the glacial stage shoreline (Shepard, 1963). Density currents were much more common on the fan in the Pleistocene when sea levels were lower and sediments were trapped and slumped periodically in the canyon.Frequency of the Pleisto- cene density currents can be estimated by counting silt laminae of density-current "tail" deposits.In a levee of Astoria Channel nearly 100 silt laminae have been counted within a 30 cm section of sediment of a six meter core with the same lithology (Figure 8D; Ap- pendix 10, core E-3).The 30 cm portion of core represents no more than 700 years of sedimentation.This calculation can be made because the six meter section of late glacial clay does not penetrate interglacial sediment of about 26, 000 B. P. age, and, therefore, represents no more than 13 500 years of sedimentation.Conse- quently, the minimum frequency of density currents is once every seven years in this part of the fan.Comparison with radiocarbon 174 dated clay of the surrounding region suggests that the late glacial clay probably is much younger than this, and that the rate of occur. rence of density currents correspondingly would be greater than one per seven years. Stratigraphy indicates that density-current activity was greatest in the earliest glacial sediments that the cores penetrated (Figure 10; Table 10; Appendix 11).Density-current layers are coarser, have greater thickness, and constitute more of the total sedimeit in the deep sediments than higher in the late glacial section (Table 8). This evidence, in addition to more and finer hemipelagic deposition higher in the stratigraphic section, implies that density-current activity was best developed at the height of the glacial activity when sea level was at its lowest. Apparently, the frequent density currents of the glacial periods eroded deep, narrow channels and deposited fine tltailfl deposits in the interchannel regions of the upper fan.The main load of coarse material probably passed through the channels in the upper fan and then was deposited in the shifting and changing distributaries of the middle and lower fan.Increases in the average thickness of glacial coarse layers and in the total amount of coarse beds at greater distances down the fan support this hypothesis. (Table 8). Worm burrows and fecal pellets are very sparse in late glacial sediments of the entire fan; this indicates that benthic activity 175 was very limited.Even the finest laminae are not disturbed by burrowing activity.In contrast, the postglacial sediments appear to be completely reworked with burrowing and fecal pellets throughout and an absence of silt laminae.Possibly, the extensive density- current deposition smothered, or inhibited, or affected the source of food of benthic life during the late glacial period.Coarse layers, which make up a major portion of density-current deposits, are usually low in organic material compared with the fine muds in the deep sea (Carey, 1966).In the late glacial deposits, hemipelagic clays are scarce between the numerous deposits of density currents. Even the glacial muds have a low content of organic carbori. compared with the postglacial clays (Kulm and Griggs, 1966).The change to predominantly foraminifera in the plankton of the late glacial also may have affected organic content and consequently benthic productivity; it resulted in a higher carbonate content in the late glacial hemipelagic sediments off Oregon (Kuim and Griggs, 1966).

Postglacial

Nearly every aspect of sedimentation was altered in the transition from glacial to postglacial times.This transformation is best noted in the hemipelagic clays by changing ratios of planktonic bra- minifera (glacial) to radiolarians (postglacial), and by a color change from gray of the glacial period to olive gray of the postglacial.In 176 the postglacial period, benthic fauna became very prominent and sediments became mottled and highly burrowed with the consequent destruction of laminations.Clay mineralogy also was altered in the postglacial deposits, with the slight change of composition and structure of montmorillonite, chlorite, and illite (Russell, 1967). Many changes occurred from the glacial to the postglacial sediments because density-current activity slackened.The number, thickness, and coarseness of coarse layers decreased as the transition to the postglacial took place.Five coarse layers were deposited in Astoria Channel inthe first 5,400 years of the postglacial period and no coarse layers have been found in the sediments deposited since the Mt. Mazama materials (ca. 6, 600 B. P. ) (Figure 10).Postglacial rate of sedimentation was greatly reduced in the interchannel regions; however, the postglacial rate of deposition in the channels was three times that of interchannel regions (Figure 31).Apparently, because of the fewer number, finer-grained, and smaller-sized density currents of the postglacial, rapid deposition occurred throughout the main channels, rather than the scouring that had taken place during the Pleistocene.Because mainly volcanic glass from Mt. Mazama, along with some detrital minerals, makes up the most recent coarse layers in nearly all cores, the last major density- current activity seems to be related to the eruption of Mt. Mazama (6, 600 B. P. ). 177 After sea level had nearly reached its present level in the postglacial, the estuary that developed trapped coarse sediments of the Columbia River.The upper canyon channels, which extended into the river mouth, also filled with sediment (Berg, King, and Carlson

1966),and density-current activity ceased.Hemipelagic clay deposition became dominant in the later postglacial.Fine material with radioactive isotopes from the present Columbia River can now be traced to the fan (Osterberg, Kuim, and Byrne, 1963).Coarse material of the shelf can be followed in the same way; it moves northwest across the shelf instead of down the canyon to the fan

(Gross and Nelson,1966).

Estimates of Astoria Fan Age

General Assumptions

Calculation of the volume of sediment in Astoria Fan are based on seismic refraction data from two representative stations (Shor, etaL,1967;Appendix 13).The difference of one kilometer in thickness of unconsolidated sediment from the apex to lower fan region correlates very well with the topographic difference of 550 fathoms (onekm; Figure 3).The seismic data also are consistent with magnetic data giving depth to basement rock below the fan (Emilia, Berg, and Bales,1967). Other seismic refraction stations, regional 178 geology, seismic profiling, magnetic, and gravity data to the east agree with seismic data for the fan (Carlson, 1967). The low velocities of the first layer most likely represent Un- consolidated to partly lithified sediments (Hamilton, 1959).To simplify terminology these sediments will be referred to as unconsolidated sediments.The wedge shape of the first layer indicates that the unconsolidated sedimentsare primarily responsible for the physiography of the fan.The velocities of the second layer are characteristic of consolidated sediments.This layer increases in thickness away from the fan apex and does not have any relation to the present topography.Since the velocities indicateasimilar second layer throughout the fan, some of the decrease in thickness in the apex region may be evidence that the consolidated sediments there have greater compaction under the thick wedge of unconsolidated sediments.Based on representative velocities, the third layer is probably basalt and the total sedimentary section of the fan overlies oceanic crust(Appendix 13). Geophysical, physiographic, and sediment data all permit the assumption that most or all of the unconsolidated wedge of sediments have come from the Columbia River.In addition, the thin cover of transgressive Holocene sands (Runge, 1966) on the Pliocene bedrock of the shelf (Byrne, Fowler, and Maloney, 1966), the buried channels which seem to connect the mouth of the Columbia River with Astoria 179 Canyon (Carison, 1967), and the high glacial period rates of deposition indicate that most of the Pleistocene load of the Columbia River apparently was funneled to the deepsea floor.If this is the case, volume of the present sediment load of the rjver may be compared with fan volume to estimate the age of the fan. Sedimentation rates provide another basis for postulating age of the fan.This is possible because thickness of the fan is known and because glacial and postglacial rates of deposition that seem to be similar and reliable have been calculated for many locations on Astoria Fan and surrounding regions (Tables 13 and 14).

Age of Fan Based on Sedimentation Rates

Based on glacial rates of sedimentation, maximum (4. 19 xio6 years) and minimim (0. 985 x 106years) estimates of time for deposition of the unconsolidated sediments may, be calculated for Astoria Fan (Appendix 13).The minimum observed glacial rate of 40cm/103 years on the fan gives a postglacial (av. 8cm/lU3years) rate change of five times which appears to be minimal for the near continental environment (se esedimentation rates section).Since 40 cm/i years is the minimum possible glacial rate and the measured rate of

170cm/103years is over 20 times the observed postglacial rates of the fan (Kuim and Nelson, 1967; Figure 27), a glacial rate ten times the fan postglacial rate, or 80 cm/103 years, may give the most reasonable age estimate of 2. 1 million years. All ages of the fan should be adjusted because rates of sedimentation are for unconsolidated sediments.If the first layer of

Astoria Fan (average of 1.6kilometers thick) is all clay lithology, a compaction to half of the original unconsolidated thickness has occurred while the layer was deposited (Hamilton,1959). Since most of the sediments of Astoria Fan are composed of hemipelagic clay with about 50 percent coarse layers, which have little or no compaction, a lower compaction factor of one-fourth may be most realistic. A compaction loss of 25 percent changes age estimates to 1. 33 times the given values (Appendix 13), or a maximum estimate of 5.58 x106 years and a minimum estimate of 1. 31 xio6years for deposition of the unconsolidated sediments. It has been shown previously that deep-sea sedimentation rates fluctuated with the advance and retreat of glaciers and shorelines. Recent evidence indicates that thePleistocene began from two and one-half to three million years ago (Savage and Curtis, 1967). A Pleistocene period of this duration would have nearly a million years of glacial advance assuming Ericson and Wollents(1964)estimates that periods of glaciation occupied about one-third of the Pleistocene.

In Astoria Channel during the Holocene transgression of the sear increased sedimentation rates and density-current activity persisted to the time of the Mazama event and to within ten meters of present 181 sea level.This suggests that high sedimentation rates may have occurred within the considerable time (Curray, 1964) of sea level rise or fall.From these data one may speculate that about one-half of the Pleistocene had increased rates of sedimentation, but that adjustments must be made for the half of the Pleistocene with lower sedimentation rates.Because the maximum observed glacial rates

(170cm/103years) would deposit 1. 6 km of sediment in less than 1. 5 million years, an adjustment for minimum sedimentation rates of the interglacial periods would affect age estimates only slightly The maximum fan age estimate is increased over three times since at the minimum rate (40cm/103 years) 0.6km of sediments would be deposited in 1.5 million years and the remaining one km would be deposited at an interglacial rate probably comparable to postglacial rates of 8cm/103years. Age estimates of several million years for unconsolidated sediments indicate that the consolidated (second layer) sediments probably were deposited in pre-Pleistocene time.Consequently, the postglacial rate of sedimentation (8cm/103 years)seems to give the most reasonable estimate of age.If a compaction to 0. 35 of original thickness is assumed (Emery and Bray, 1958) because of thickness of the first layer, a maximum age estimate of 29, OOQ 000 years is possible.Age of the second layer would be considerably less if it contains numerous coarse layers and deposition of glacial periods; 182 assuming the maximum sedimentation rate (170cm/lU3 years) would give a minimum estimate of one million years time for deposition of consolidated sediments.

Age of the Fan Based on Present Sediment Load of the Columbia River

It appears justified to assume that most of the Pleistocene sediment load of the Columbia River was deposited on Astoria Fan. Consequently, the volume of unconsolidated sediments on the fan divided by the present maximum and minimum estimated volume of sediment carried by the Columbia River each year can be used to calculate possible ages.Considering 25 percent loss from compaction, the maximum and minimum ages respectively of 2. 70 and1.97 million years for deposition of the unconsolidated sediments cau be estimated (Appendix 13). Comparisons with other River drainages suggest that sediment loads of the Pleistocene Columbia River were greater than present loads, and that the age estimates based on present river loads may be conservative. A Pleistocene denudation rate of 0. 27cm/103years can be calculated for the Columbia drainage basinif a Pleistocene age of 1. 5 xiO6years is assumed.This is extremely low consider. ing average present denudation rates of 12 to 21cm/103are found for similar mountainous areas (Menard, Smith and Pratt,1965). Since sediment load of the Columbia River is one-half of the load cited for the Rhone River and the Columbia's drainage basin is over five times as large, estimated present sediment load seems to be low for the Columbia River (Menard, Smith, and Pratt, 1965).

Evaluation of Age Data for Astori,a Canyon and Fan

Several lines of reasoning indicate that the unconsolidated sedi.. ments which form the fan proper have been deposited mainly during the Pleistocene.If the maximum observed sedimentation rate

(170cm/103years), the postulated length of glacial periods (1. 5 of a three million year total), and compaction rates (minus 25 percent change in thickness) are used for calculation, deposition of the entire volume of unconsolidated fan sediments could have occurred during the Pleistocene.If the more likely average rate of SOcrn/103 years is used with the same assumptions, 1. 3 km out of 1. 6 kmtotal depth of unconsolidated sediments or most of the fan would have been deposited in the Pleistocene.Using the present sediment loads of the Columbia River to estimate the time required to deposit the unconsolidated sediments (two to three million years) also indicates a Pleistocene fan age; this assumes that loss to compaction was 2, percent, that the total sediment load of the river was deposited on the fan, and that the age of the Pleistocene is two to three million years,If the Pleistocene age eventually is found to be less than the 184 present 2. 5 to 3 million year estimates, or if later data support maximum estimates of fan age, neither of these would increase the age of the unconsolidated fan sediments beyond the Pliocene. The consolidated sediments (second layer) do not appear to be related to the topography or history of the fan.From all age estimates, these consolidated sediments seem to have accumulated during the Late Tertiary. The tectonic history of the Oregon continental margin and the age estimates of the fan both suggest that the main development of Astoria Canyon and Fan took place dnring the Pleistocene.It appear that the structural framework of the continental terrace developed with the beginning of the Coast Range orogeny in Late Pliocene.This provided the tectonic setting for Astoria Canyon and Fan; fluctuating sea levels and accelerated sedimentary processes of the Pleistocene then facilitated the formation of the canyon-fan system.In building the fan, sediments amounting to about 70 times the volume of the canyon (400km3,Carison, 1967) passed through the canyon.The scouring by sediments transported to the fan, subaerial erosion from lowered sea levels, and sediment mass movement along an original structural discontinuity of the canyon (Carlson, 1967) all contributed to enlargement of the canyon.Glacial scouring on land, cataclysmic flooding from the breaking of ice block dams of glaciai lakes, high river flow from glacial melting, lowered sea level, and trapping of 185 longshore drift and river sediment load in the canyon head all increased sediment erosion and transport through the canyon pathway and helped to cause high rates of deposition that built the fan mainly during the Pleistocene. XI.GEOLOGIC SIGNIFICANCE

General Characteristics of Fans

The amount of material discharged, size of drainage basin, and sediment size appear to control the size and gradient of any fan, whether it is an alluvial fan in a mountainous area or a deep-sea fan bordering the continental slope.If the drainage basin and sediment load is large and the sediment size of the river ultimately feeding the fan is small, the fan gradient is low and the fan area is large. The same sequence of channel development occurs on both land and sea fans.Channels tend toward reaching grade throughout their profiles. On the steep, upper fan surface the channels are few in number, deep, narrow, and have a lower gradient than the fan surface; on the middle and lower fan the main channels divide into many shallow distributaries that have a higher gradient than the fan surface.The shifting courses of distributaries in the middle and lower fan result in a high quantity of stratified and sorted deposits throughout these regions. The shape of deep-sea fans commonly is asymetrical,. whereas alluvial fans, which are smaller, normally are semicircular. Because of the usual large size of deep-sea fans, major structural features of the deep-sea floor, such as fracture zonesabyssal hills, and seamounts, often restrict deposition and cause asymetrical 187 configuration.It has been postulated that the coriolis effect also influences deep-sea fan shape since major channel development and deposition moves to the left in the northern hemisphere and tends to parallel the continental slope. History of the fan valley systems and of sedimentation on

Astoria Fan may support the "left hook" hypothesis (Menard,1955). Fragments of a series of main channels in the fan apex seem to h3ve developed in sequence from north to south or to the left.The occurrence of Mazama ash in the last deposits of major density currents reveals that the channels farthest to the left have been func- tional most recently.Also, the main development of the fan has been to the south along the slope.However, Cascadia Channel, a major structural feature on the western fan boundary, may have been another factor preventing deposition to the west and the symmetrical shape of Astoria Fan.

Review of the Density-Current Process

All investigators of deep-sea fans similar to Astoria Fanhave reported that density currents are the main sedimentary process depositing coarse materials on the fans (Wilde,1965,Monterey Fan;

Menard, Smith, and Pratt,1965,Rhone Fan; Heezen, Hollister, and Ruddiman,1966,Hudson Fan).New data from Astoria Fan provide further insight into the mechanics of density-current processes on the fans.The content of benthic foraminifera, plant debris, glauconite, and clay indicate that fine sediments of the slope were incorporated in the slumps that generated density currents.In postglacial times the coarsest debris (Figure 8F) was dropped in thick layers near the canyon mouth,In contrast, it appears that the coarser density currents of the late glacial period tended to scour rather than deposit in upper fan channels.In postglacial times as the main mass flowed throughout the channels, sorting and deposition of thick layers occurred.During the transport down the channels sorting within any density current improved because clay and platy materials were sorted from the coarsest debris and lost to the "tail" of fine materials.Thetail" of fines billowed above and spread beyond the levees of the main channels. Ash and general stratigraphy of thick, coarse channel deposits and thin correlative interchannel deposits intheupper fan seems to substantiate Menard's (1955) idea that the coarsest material of density currents remains in the channels and the fine-sized material over- flows to build the interchannel areas of upper fans.However, this is not the case in the middle and lower fan areas where distributary development results in deposits from all phases of the density current being present throughout the section. A list of the 22 important characteristics of density-current deposits was compiled from exhaustive literature reviews by Kuenen (1964). Most of these characteristics are exhibited by deposits on Astoria Fan, but some require qualification because of the new data from this study. Numerous investigators have noted that the coarsest materials from density-current deposits are pebble sized and occur in the main channels near the sediment source (Shepard and Einsele, 1962;

Hand and Emery,1964;Wilde,1965). This localized occurrence of the coarsest material emphasizes the importance of channels in the distribution and stratigraphy of coarse debris in deep-sea fans. Several authors have stated that coarse beds become thinner, more fine-grained, and comprise a smaller part of the total section away from the sediment source (Potter and Pettijohn,1963;Kuenen,

1964;Emery,1965). This may be true in very restricted basins, such as the collapse caldera of Crater Lake, Oregon (Nelson,1967), but in deep-sea fans this consistent change from the source occurs only on the floors of the main channels, if at all.The greatest lateral changes take place from the channel to interchannel deposits in the upper fans.Few coarse layers occur in the interchannel areas of the upper fan because it receives only fine 11tail' deposits, whereas many coarse layers occur in the upper channels.Because of distributary development, very thick coarse layers are found throughout the middle and lower fan channel and interchannel regions.In the main channels only slight changes in thickness, 190 number, and particle size of coarse layers can be distinguished beyond, the gravel lenses in the uppermost channels (Shepard,1961;

Hand and Emery,1964;Figure 22). Reports of widespread correlation of coarse layers by seismic profiling (Kuenen,1964)are given credence by the traceable ash horizons of Astoria Fan.Other studies have shown that detailed mineralogic work in regions with highly variable detrital sources or ash layers permits apparent widespread correlation of coarse layers

(Holterdahl,1965;Ryan, Workum, and Hersey,1965). Double tuffaceous layers can be followed throughout Astoria Channel because of their distinctive mineralogy and position as the first coarse layers in the cores.Both layers may not always be found in the interchannel regions and occasionally are absent even near the canyon mouth (Ap- pendix 5 )c.Again, a rapid change and interplay between channel flow and spread of the fines is evident. In genera]., most investigators of density-current deposits have found it impossible to correlate lithoj.ogy layer by layer over a basin

(Gorsline and Emery 1959;Ericson, etal.,1961;Shepard and

Einsele,1962;Nelson,1967). Cores taken a meter apart often have dissimilar coarse layer sequences in this study.Six meter piston cores taken about one mile apart could not be correlated beyond the first meter.Shepard and Einsele(1962)observed that they could not correlate thin sand layers between trident cores only half a meter 191 apart.Distribution and variance of the ash horizons in channel and interchannel regions of Astoria Fan suggest that channel development probably is responsible for the discontinuity arid, diversity of thick. ness arid coarseness of a coarse bed from a single density-current event.When stratigraphic columns of such variable beds and channeled topography are compared, bed-by-bed correlation is not likely unless a distinctive mineralogy can be traced. Astoria Fan deposits fit into the category of oceanic abyssal plain deposits as described by Rusnak and Nesteroff(1964). The fan deposits. contain more clay, are finer, and have better sorting than density-current deposits of smaller basins (Gorsline and Emery,

1959;Nelson,1967). New data from Astoria Fan indicate that clay content and.sorting of density-current deposits appear to have trends away from the source.In the channels of upper Astoria Fan, coarse layers have poor sorting and a high content of clay although they also contain coarse material up through gravel size.In the middle and lower fan clay content is low and sorting is moderate to good in the lower part of coarse layers.The very fine-sized coarse layers or T?tai1I deposits have high amounts of clay and poor sorting anywhere on the fan whether they occur above thick coarse layers or in interchannel regions. Evidence is accumulating that clay content of the density- 192 currents may be an important factor controlling density-current flows and deposits.In the small caldera basin of Crater Lake, slope sediments have a very low clay content and consequently, the slumps generate density currents low in clay (Nelson, 1967).In this environment prominent channels with even gradients do not develop and large amounts of coarse material are not funneled to the far reaches of the basin as they are in deep-sea environments (Figure 10; Table 8; Appendix 11; Gorsline and Emery, 1959).As a result, in the basin floor of Crater Lake there is an idealized change from many thick,coarse, and unsorted sands at the basin edge to few thinfine-grained, and well sorted sand layers at the center of the lake.Geologists have postulated this change for all turbidite environments (Potter and Pettijohn, 1963; Kuenen, 1964; Emery,

1965).In actuality the pattern in modern deepsea environments appears to be one or two deep, main channels with thick, coarse, and unsorted deposits that cut through laminated silt and clay deposits near the sediment source (Figure 10; Table 8; Appendix 11; Hand and Emery, 1964).In the distal regions, which have lower gradients than the proximal regions, the channel systems break into distributaries that constantly shift to deposit many thicksorted, and medium silt to medium sand layers throughout the section.(Figures 10 and 27; Table 8; Appendix 11; Hand and Emery, 1964; Gorsline and Emery, 1959; Buffington. etal,, 1967). 193

Significance of Deep-sea Fans in Geologic History

The high frequency of and high sedimentation rates of density- current deposition on modern fans compared with other environments suggests that deep-sea fans may be built quite rapidly (Table

14).La Jolla and Scripps Canyons trap littoral drift material which generally flushes down the canyons to the deep-sea floor every one to two years (Dill, 1964; Chamberlain, 1964).Gorsline and Emery (1959) observed that discontinuous sediments were deposited about once every 400 years in the middle of San Pedro and Santa Monica Basins; they probably were being deposited every one to ten years on the fans from canyon mouths feeding the basins.In the modern Congo Canyon that heads in the present river, over 50 densitycurrents have occurred in the last century.During the late glacial period the rate was greater than one density-current every seven years on Astoria Fan.However, the great change in frequency of density-currents on Astoria Fan in the postglacial (five events in Astoria Channel from 1 2, 000 to 6, 600 B. P. and no major events since) reveals that rates even in the same environment may be quite variable.For example, in Tongue of the Ocean, Bahamas, frequency of density-current events is one per 460 to 10, 000 years (Rusnak and Nesteroff, 1964).For rocks, estimates of one per one hundred to one million years have been made (Kuenen, 1964). 194

Because of the high deposition rates and frequency of densitycurrents in the Pleistocene, many investigators believe that the major development of deep-sea fans occurred at that t.me (Heezen and Hollister, 1964b).Data from Astoria Fan agree with this hypothesis, but investigators of some deep-sea fans have estimated ages to be much older than the Pleistocene.Re-evaluation of data from these apparently older fans suggests that the fai physiography may have developed mainly from deposition of unconsolidated sediments in the Pleistocene.The post-Oligocene age of Rhone Fan cited by Menard, Smith, and Pratt (1965) refers to deposition that includes consolidated sediments.If unconsolidated sediments of the Rhone Fan were deposited in the Pleistocene, a river load six times the present load would be required(Menard, Smith,and Pratt, 1965). Evidence presented earlier suggests that Pleistocene deposition rates were five to ten times the present rates; this would permit possible deposition of the unconsolidated material on the Rhone Fan during the Pleistocene. Wilde (1965) estimated that the formation of Monterey Fan be- ganin the Oligocene if data of modern river flow are used to calculate the volume of sediment.He calculated a sedimentation rate of 1 cm/103 years using river flow, whereas in similar environments and surrounding environments a postglacial rate of 8cm/lU3years has been reported (Gorsline and Emery, 1959; Ericson etal., 195

1961;Emery and Bray, 1962; Heezen and Hollister,1964b). Wilde's estimate does not account for the materials now trapped in estuaries like San Francisco Bay nor for the high sedimentation rates of the Pleistocene.Using the normal postglacial rate or Pleistocene rates of five to ten times places the deposition of unconsolidated sediments primarily in the Pleistocene epoch. The destiny of continental rise sediments and deep-sea fans has been a topic of current interest for marine geologists.Dietz

(1964,p. 52) believed that "primary continental slopes are composed of collapsed continental rises compressed by sea floor thrust- ing. " Since fans are built upon the continental rise, fan sediments also would be incorporated into the continental terrace. The Oregon continental terrace appears to be an example of this process of sea floor spreading, continental rise and terrace compression, and continental accretion. A relatively rapid spreading of the sea floor off Oregon over the last 80 million years has been suggested; this movement has been east toward the continent from Juan de Fuca Ridge (Vine,1966). Geologic studies indicate the possibility of compressional forces normal to the coast and reveal that the rocks of the shelf may have been uplifted as much as 1000 m from middle slope depths (Byrne, Fowler, and Maloney,1966). This uplift is evident by the surface samples of the uplifted rocks that have bathyal foraminifera, and sediment texture and composition 196 similar to sediment of the lower slope.Because the sediments constituting the surface rocks of the shelf banks were originally deposited in bathyal depths, it is likely that rocks at depth are sediments from the continental rise or fan as Dietz (1963) postulated.

Maloney(1964)observed rocks on the lower slope with apparent

tturbiditeu beds similar to those of the present fan; this again lends support to the hypothesis that the sediments of the continental rise underlie the Oregon shelf bedrock. If the simplest model of vertical uplift is assumed, the average maximum horizontal component of the continental accretion has been

16km and the greatest possible measurement has been estimated to be 50 km alorg the central Oregon shelf and slope (Byrne, Fowler, and Maloney,1966). This evidence, together with the younger age of the shelf rocks compared with Coast Range rocks (Byrne, Fowler, and Maloney,1966),and the history of a continual westward shift of the Tertiary eugeosyncline axis (Snavely and Wagner, 1963), again make it quite likely that the underlying rocks of the continental terrace were deposited as eugeosynclinal sediments on the continental rise and slope. The new data of the Oregon Coast Range and continental terrace history provide more specific evidence for the theory of continental accretion and the idea that continental rise deposits of fossil fans should be present in eugeosynclinal or flysch rocks of the 197 continental framework.However, some investigators have stated that graywackes of flysch deposits are not similar to modern density- current sands (Kuenen,1964;Emery,1965). The sands lack the amount of matrix that graywackes have and thus are better sorted. Recently, it has been suggested that graywackes may be a secondary development from unstable constituents within the layer (Cummins,

1962). It seems reasonable that the upper part of the coarse layers, which are high in matrix and micas, may furnish the necessary matrix material for the layer once it is under compaction. Mineralogy and texture of the sediments in Astoria Fan indicate that these sediments maybecome gaywackes similar to those of flysch deposits.Whetten(1966)observed that the mineral composition of Columbia River sediments is identical to that of average graywackes.Previous data show that the coarse layers of the fan have the same mineralogy as the Columbia River sands.In addition, the sands of the fan have matrix naterial which was incorporated during the formation and flow of the density currents. New data of this study and other studies can be used to speculate on the future of Astoria Fan materials.The recent construction of dams in the Columbia River and the Holocene rise of sea level appear to result in entrapment of sediments long before they reach the Astoria Canyon-Fan sequence.The present canyon and fan valley systems are filling rapidly and no longer funnel coarse sediments to the deep-sea fan system.If this trend continues without renewed glaciation, thickening of the wedge of sediments on Astoria Fan will be very slight.If spreading of the sea floor continues at the postulated high rates (Vine,1966),the present sediments eventually will become part of the continent. Application of stratigraphic, textural, and compositional data of this study should aid in the identification of fossil submarine fan deposits with flysch and eugeosynclinal rocks.Wilde(1965)compiled a list of flysch type formations that appear to possess characteristics of present deep-sea fans.Well-documented reports of fossil deep-sea fans have appeared in the literature (Suliwold,1960;

Walker,1966;Bartow,1966).

Application to Ancient Rocks

Comparison of the data from this research with studies of other modern environments and rocks (see comparison sections in Discus- sion and Interpretation chapter) yields the following criteria for identification of fan sediments in the geologic column and suggests characteristics for a model of deep-sea fans (Figure 32).

1.Deep-sea fans may have an asymetric or semicircular shape depending upon the form of the basin and the tectonic framework (Table 4).

2.Fans have steep, narrow, and deep, discrete channel SIZE SORTING COMPOSITION LITHOLOGY GECNETRY

/ CHANNEL COARSE .r- ' LAYERS very graywacke sands lack of sandstone and / / Upper Fan gravel poor displaced fauna / grading and muddy conglomerates _ .j ., ,'(/ &detritals structures withinteibedded - I - I mudstone o - - - ' fine -' 5-', . / 4, Lower Fan sand moderate same as upper graded beds sorted sandstone -. - / channel plus cross-bedded intetheddedwith .- .,,- .. 7/ ', ,,,I/ grading of mica, laminated claystone --- light and heavy cut fill - /1 minerals, forasns mud claris -, 1,/,

5, ' ,i' / INTERcI-IANNV. 3 ,'J.' / COARSE LAYERS f/f,. .. Upper Fan fine very high mica& Silt laminae mudstone with (p/ ' -' suit poor plant fragments common silt lamina .'J/ 6 , - / .2 4 $ Lower Fan fine moderate same as lowet same as lower sorted sandstone 4 -/ sand fan channel fan channel inteibedded -. ,,i \ '5 coarse layers cosine layers withclaystone .

HeIIPELAGIC 5 I

Upper Fan silty very high terriginous worm burrows mudstone . / I clay poor &lo:planlc- :llets iL-' )

Lower Fan clay poor low terriginoua claystone 6 '. . . &planktonics -.

Indicate gradation and magnitude of parameters Figure 32.Characteristics of a deep-sea fan model. 200 fillings near the dominant sediment source, and branching, shallow distributary fillings at the distal end (Figure 5; Menard, Smith and Pratt, 1965; Wilde, 1965; Walker, 1966).

3.Divergent currert lineation patterns may be typical of fan sediments because of distributary patterns, "left hook" (inthe northern hemisphere) shifts of channel systems, and burial of old channel systems (Figure 5; Menard, Smith and Pratt, 1965; Wilde, 1965; Walker, 1966).Because channels tend to shift ("hook") in the same direction, they eventually parallel the slope.Corsequently, linear trends of fans are radial and may be parallel or normal to the continental slope or basin edge.

4.Upper channel deposits contain mainly coarse sediments and are flanked by levee deposits of numerous, thin interbeds of silt and clay:theymay cut clay-shale facies of density current "tail" deposits.Lower channel deposits may cut old distributary channel deposits (Figures 8,10, 27; Hand and Emery, 1964; Moore, 1965; Menard, Smith, and Pratt, 1965; Wilde, 1965; Walker, 1966).

5.Because of density current flow and coarse layer deposition in channels, and distributary development on the middle and lower fan, coarse layer:shale layer ratios are high in all the channels, high in the interchannel regions of the middle and lower fan, and low in interchannel regions of the upper fan (Figures 32 and 33; Appendix 14; Gorsline and Emery, 1959). PLEISTOCENE

27000 26000

'U 46

15 I- 45000

Piston Core and Phleger Core sample station. -( NAUTICAL MILES Contour Interval : 100 fathoms 50 fathoms 0- 10 20 D------Pleistocene not encountered KILOMETERS Compiled by Hans Nelson 202

PQST(1 AC1AI

12 7 0 0 12 6 00 400 300 200 1100 1000

i:3/ '44 1500 1:2,1

+fJ' + J1 1-) ( ,-aIl / 1:2,) la ci (1:3,/

1:4 / 1:18 -4 1:2 aIl clay 1:5

1:2 I550

\ ik

1:20 ------l:32 - 1.13 000 600 ASTORIA "-----', FA N ff1400 I500 11111<1:2 550 0 SO 20 Piston Core and Phieqer Core sample station. NAUTICAL MILES Contour Interval 100 fathoms 0 50 20 50 fathoms I_-_-_l KILOMETERS compiled by Hans Nelson

Figure 33 (a & b),Coarse layer:shale ratios for late glacialand postglacial sediments of Astoria Fan,Calculations are based on the assumption that compactionof mud to shale is approximately 35% of the formerthickness (Emery and Bray, 1962). 203

6.High clastic ratios and thickness of layers do not neces- sarily indicate nearness to source or basin margin in fans as has commonly been stated for turbidite environments (Figures 32 and 33; Appendix 14; Potter and Pettijohn, 1963; Kuenen, 1964; Emery,

1965).

7.Cia stic ratios may vary with depth in fans because channel patterns may shift, sediment source may change, and amOunt and size of source material may vary (Figures 10, 32, 33; Table 8).Lack of coarse beds throughout a stratigraphic init in a fan probably mdi- cates elimination of a source of coarse debris for canyons and slopes of the basin.Rise of sea level during interglacial periods may have resulted in such stratigraphic discontinuity in present deep-sea fans (Figures 32 and 33).

8.With the exception of the upper channel gravel layers, the fan coarse layers consist of fine-grained sands to coarse silts, are moderately sorted,. and have from about three to ten percent clay (Figures 11-16; Gorsline and Emery, 1959; Sullwoid, 1960; Shepard, 1961; Shepard and Einsele, 1962; Heezen, Hollister, and Ruddiman,

1966).

9.Proximal density-current deposits differ from the distal deposits in that they have gravels, relatively high clay content, poor sorting, poor grading, sharp top and bottom bedding contacts, and consist mainly, of thick beds with an absence of sedimentary MIE1 structures of Mturbite!J deposits (Table 10; Hand and Emery, 1964; Bartow, 1966; Walker, l966;Bouma, 1962).

10.Coarse layers become better sorted, contain less clay, and have higher silt:clay ratios away from the source.

11.All -characteristics attributed to Hturbiditefl sedimentation occur in the lithology of modern and fossil submarine fans and do not differer.tiate fan turbidites from those of other environments (Gorsline and Emery, 1959; Suliwold, 1960; Shepard and Einsele, 1962; Kuenen, 1964; Hand and Emery, 1964; Walker, 1966;Tab1e 9).

1 2. Sedimentary structures of both ancient and modern fan turbidite depo sits include graded beds, lamination, cross -lamination, cut and fill, and mud clasts; these are in typical sequences corn- parable to those of turbidites from any environment (Figures 23, 24, 25; Emery and Gorsline, 1959; Bouma, 1962; Heezen and Hollister, 1964; Kuenen, 1964).

13.Size grading is prominent and proceeds from irregular grading near the base tovery distinct grading at the top of the layer (Kuenen, 1964).

14.The following slump and bedding plane structures can be seen in the turbidite rocks of fans: flow markings, ripple markings, and load deformation structures (Sullwold, 1960).

15.The composition of coarse fraction of the coarse layers is graded both in ancient and recent fan deposits, but, the grading 205 characteristics do not differentiate fan sediments from other turbidites.

16.The coarse layers grade to a high content of mica and plant material at the top of the layer (Figure 25, Appendix 10; Gorsline and Emery, 1959; Sullwold, 1960; Shepard, 1961; Shepard and Einsele, 1962; Wilde, 1965).

17.Composition of heavy minerals grades vertically up mdi- vidual layers andhorizontally in the coarse layers (Appendices 7 and 10; Stanley, 1963; Wilde, 1965).

18.Generally, content of heavy minerals decreases in amount vertically up the layers and horizontally away from the source, even if size competency is maintained over a great horizontal distance (Appendices 7 and 10).

19.Displaced foraminifera in rocks and recent sand of fans grade from benthic species of a single environmental suite at the base of coarse layers to overlying material that has mixed displaced assemblages from all the depth environments through which the density current has passed (Appendix 8; Natland, 1963; Figure 25).

20.According to light mineralogy, the coarse layers of fans are generally arkosic or lithic wackes and arenites (Figure 17; Sullwold, 1960 Shepard and Einsele, 1962; Wilde, 1965).

21.Matrix amount increases vertically up a coarse layer; consequently, arenites may grade to wackes at the top. 22.Fine"tai11deposits of density currents are extensive above each coarse layer (or turbidite in rocks) and between closely- spaced coarse. layers. As a result, hemipelagic sediment is a small proportion of the total deposit in a density-current environment (Figures 10, 25, 33; Table 8; Appendix 11; Bouma, 1962; Buffington, et al. ,1967).

23.Horizontal textural trends in hemipelagic fan. sediments, such as finer size, decreasing silt:clay ratios, higher clay content, better sorting, and more negative skewness away from the fan apex and the bordering continental slope, help to identifysediment sources and outline the regional setting (Figures 12, 13, 14, 19; Table 5).

24.Horizontal trends of clay, composition also aid in finding the location of sediment source and basin margins because the amount of biologic coarse fraction increases away, from the continental slope and fan apex as the content of masking terrigenous debris decreases (Figure 18-21).Specific types of biologic materials increase (radiolarians and planktonic foraminifera) or decrease (pollen and plant fragment terrigenous debris) away, from the continental terrace.

25.Shifts in the shoreline distance and in distance of source of pelagic constituents can be detected in a vertical section of clays by changing ratios of lateral trends of texture and composition (Figure 18). 207

26.Hemipelagic sediments of the continental slope bordering the fans can be identified by the high quantity of terrigenous debris, the relatively high proportion of diatoms, and the general lack of turbidite beds (Maloney, 1965; Carlson, 1967).

27.Hemipelagic sediments from the abyssal plain bordering the fans have very high contents of planktonic organism, have low rates of deposition, and lack gradients of terrigenous and planktonic debris (Kuim and Nelson, 1967; Figures l8-2127). BIBLIOGRAPHY

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Blissenbach,. Erich.1954.Geology of alluvial fans in semiarid regions.Bulletin of the Geological Society of America 65: 175-190. 209

Boettcher, Richard.1967.Research assistant, Oregon State University, Department of Oceanography. Personal communication.Corvallis, Oregon.

Bouma, A. H.1962.Sedimentology of some flysch deposits, a graphic approach to facies interpretation. Amsterdam, The Netherlands, ElsevierPublishing Co.168 p.

Bouma, A. H.1964.Turbidites.In:Turbidites, ed. by A. H. Bouma and A. Brouwer. Amsterdam, The Netherlands, Elsevier Publishing Co.p. 247-256.

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Williams, H., F. J. Turner and C. M. Gilbert. 1958.Petrography. San Francisco, Freeman. 406 p. APPENDICES 225 APPENDIX I LOCATION OF CORING STATIONS AND LENGTH OF CORES OBTAINED PhlégerPiston Collec- Core corecore tion station Depthlengthlength date number Latitude Longitude(fathoms) (cm) (cm) 8/25/64 Al 45°51' 125°39.5' 1145 52 519 1/7/65 AZ 45°56.9' 125°46.5' 1265 38 620 1/6/65 A3-1 46°18.2' 126°40.0' 1460 45 600 1/6/65 A3-2 46°02.1' 126°06.4' 1405 40 582 1/6/65 A4 46°18' 126°48' 1472 36 234 1/6/65 A5 46°19.9' 126°49. 6' 1460 29 560 8/8/65 A4-A 46°11.O' l26°23.4' 1459 28 475 8/8/65 A4-B 46°08.9' 126°22.5 1458 52 21 1/8/65 B2 45°52.3' 125°43.7' 1225 29 400 1/7/65 B3 45°52.5' 125°53.5' 1330 41 262 8/26/64 B4 45053.1 126°34.0' 1460 51 609 8/7/65 B5 45053t 125°10' 1425 33 518 8/8/65 B6 45053t 126°47.5' 1481 45 356 8/25/64 C2 45°49' 125°45.5' 1233 42 560 8/25/64 C3 45°41.8' 126°07' 1393 48 470 1/5/65 C4 45°30' 126°45' 1500 40 600 1/6/65 C4-2 45°29' 126°46' 1504 28 585 1/7/65 D2 45°49.8' 125°35' 1185 53 405 1/7/65 D3 45°39.9' 125°47.5 1310 40 600 1/5/65 D4 45°21' 126°10' 1438 26 582 1/8/65 D10 45°48.5' 125°36.9' 1195 34 214 1/7/65 E2 45°433' 125°37' 1252 42 600 1/7/65 E3 45°29' 125°42.2' 1338 47 540 1/5/65 E4 44°58' 125°54' 1510 49 0 1/7/65 E7 45°38.2' 125°37.7' 1235 41 42 226

APPENDIX I (continued) PhiegerPiston Collec-Core corecore tion station Depthlengthlength date number Latitude Longitude(fathoms) (cm) (cm) 1/8/65. F2 45°497' 125o315t 1120 28 540 1/7/65 F3 45°37.2' 125°28.5' 1288 44 50 1/5/65 F4 45°132' 125°33.O' 1425 37 257 8/7/65 Gi 46006.11 12504771. 1370 41 396 8/21/62 Kl 45°08' 1260101 1458 51 530 8/21/62 K2 45°35.2' 126°25.8' 1446 50 600 9/7/65 6509-1 44°39.1' 125°23.1' 1540 8 275 9/8/65 6509-2 44°40.5' 1250401 1535 56 360 9/8/65 6509-3 44°42' 125°55.4' 1562 59 252 9/8/65 6509-4 440571 125°47.2' 1519 42 504 9/8/65 6509-5 45015.41 125°4i.8' 1450 67 148 9/9/65 6509-6A 440.38.41 12602941 1542 23 300 9/9/65 6509-7 44°59.2' 12603i.2t 1520 18 270 9/10/65 6509-8 45°i1' 126°47' 1529 27 0 9/10/65 6509-9A45°22.8' 127°06' 1541 15 230 9/12/65 6509-16 44°4O' 126°54.5 1548 18 270 APPENDIX II TEXTURAL ANALYSES OF SEDIMENT SAMPLES )* 1957)* SampieCoreDepth in Percentage Inman(1952 Folk and Ward( Mean Sothig Skewness - # # core (cm) Sand Silt Clay Median Mean Sorting Skewness 1.63 1 K-i 6 .73 23.29 75.98 9.54 9.32 1.81 -.12 9.40 -.12 2 K-i 47 .41 34.20 65.39 8.88 9.70 3.48 .23 9.42 3 37 .18 3 K-i 52 .73 57.30 41.97 7.44 8.11 2.95 .23 7.88 2.76 .22 4 K-i 55 64 36 28 67 6 01 6 81 2 62 30 6 54 2 46 38 5 K-i 57 i.02 34.98 64.00 8.80 8.76 2.09 .02 8.78 1.91 -.03 6 K-i 65 45 59 46 40 09 7 26 7 89 2 40 26 7 68 2 26 i9 7 K-i 70 15.06 71.77 13.17 5.06 5.75 1.73 .40 5.52 1.92 .46 8 K-i 73 .48 37.42 62.ii 8.87 8.64 2.45 -.09 8.72 2.34 -.15 9 K-i 108 33 46 75 52 92 8 21 8 42 2 60 08 8 35 2 44 04 10 K-i 122 1.00 43.94 55.06 8.35 8.55 2.94 .07 8.48 2.74 .05 ii K-i i49 41 57 4i 42 19 7 42 7 72 2 66 ii 7 62 2 39 10 41 12 K-i 152 23.04 74.31 2.65 4.19 4.49 .69 .43 4.39 .77 - -07 13 ic-i 155 1 02 35 63 63 35 8 79 8 73 2 36 02 8 75 2 25 15 14 K-i 213 24 34 41 65 35 9 04 9 47 3 04 14 9 33 2 76 64 15 K-i 216 90 85 01 14 09 5 14 5 95 1 45 56 S 68 1 73 16 K-i 170 .17 29.47 71.36 9.65 9.83 3.10 .06 9.77 2.95 -.00 03 17 K-i 310 08 35 01 64 91 9 18 9 28 2 66 02 9 25 2 42 1 57 19 18 K-i 313 85 86 12 i3 02 5 95 6 04 1 54 06 6 01 19 K-i 31S .19 39.28 60.53 8.97 9.46 2.74 .18 9.30 2.69 .08 20 K-i 374 12 48 66 51 22 8 09 9 37 3 14 41 8 94 2 96 34 21 K-i 376 88 87 54 ii 58 5 22 5 86 1 61 40 5 65 2 36 58 22 K-i 378 .00 39.52 60.48 8.77 9.51 2.89 .26 9.26 2.59 .25 23 K-i 510 08 39 41 60 51 8 75 10 35 3 96 40 9 82 3 62 42 24 K-i 513 5 70 89 88 4 42 5 14 5 39 91 27 5 31 1 01 31 25 K-i 518 1 65 44 02 54 32 8 57 9 48 3 80 24 9 17 3 48 22 26 K-2 316 1 24 31 30 67 46 9 09 9 15 2 13 03 9 13 1 96 00 27 K-2 340 31 74 67 25 02 6 30 7 28 2 13 46 6 95 2 07 46 19 28 I{-2 348 24 32 71 18 4 50 4 6i 4 61 85 01 4 61 96 29 K-2 355 50 36 23 63 27 8 73 8 67 2 01 -03 8 69 1 81 -03 APPENDIX II (continued) )* 1957)* SampleCoreDepth in Percentag Inman(1952 Folk and Ward( L. # core (cm) Sand Silt Clay Median Mean Sorting Skewness Mean Sorting Skewness 30 I{-2 450 23 37.03 62.74 8.80 8.95 2.09 .07 8.90 1.96 .03

31 K-2 575 . 13 76.00 23.87 6.30 7. 34 2. 14 .49 6.99 2. 13 .50 32 K-2 583 45 31 51.30 3.39 4.09 4 21 .71 .16 4. 17 .84 .29 33 K-2 588 .04 43.35 56.61 8;42 &58 2;17 .07 8.53 2.09 .00 34 B-4 378 .00 40.19 59.81 8.62 8.81 2.06 .09 8.74 1.86 .09 35 8-4 498 .52 41.21 58.27 8.54 8.72 2.18 .08 8.66 2.02 .05 37 B-4 401 .05 43.49 56.46 8.41 8.63 2.12 .10 8.56 1.90 11 38 B-4 498 .52 41.21 58.27 8.54 8.72 2.18 08 8.66 2.02 05 39 C-2 298 .02 34.09 65.88 9.05 9.13 2.26 .03 9.10 2.05 .02 40 C-2 395 .04 36.92 63.04 9.01 9.21 2.50 08 9.14 2.27 .08 41 C-2 498 .17 36.34 63.49 8.95 8.97 2.47 .01 &97 2.33 -.04 42 C-2 561 .00 32.14 67.86 9.20 9.21 2.35 .00 9.21 2.15 -.01 43 B-4 595 .81 49.56 49.63 7.93 845 2.35 .22 8.28 2.23 .15 44 B-4 599 .25 65.39 34.36 6. 87 7 70 2 46 .34 7.43 2.25 .36 45 B-4 603 .08 49.58 50.34 7.99 8.38 2.33 .17 8.25 2.16 13 48 B-4 23 .63 79.00 20.37 539 6.75 2.27 .60 6.29 2.16 61

.14 50 B-4 103 .00 54.24 45. 76 7.56 7.99 2. 18 .20 7.85 2.05 51 B-4 239 .45 37.77 61.77 8.72 8.70 2.22 -.01 8.71 2.01 -.02 53 C-2 76 1.38 72.28 26.35 662 7.52 1.93 .47 7.22 1.98 .39 54 C-2 84 .32 75.89 23.79 6.67 7.27 1.57 .38 7.07 1.57 .35 55 C-2 90 1.47 38.19 60.34 8.69 8.78 2.29 .04 8.75 2.21 -.03 57 C-2 140 11.91 37.10 50.99 8.06 7.77 348 -.08 7.87 3.11 -.07 58 C-2 161 .00 36.91 63.09 9.03 9.04 2.77 .00 9.03 2.61 -.05 59 C-2 239 .00 31.15 68.85 9.52 9.54 2.79 .01 9.54 2.62 -.04 61 K-2 38 152 76.58 21.90 5.92 7.03 2.24 .49 6,66 2.27 .51 62 K-2 118 54.79 43.11 2.15 3.88 3.96 .79 .10 393 .91 .15 63 K-2 125 3.25 28.58 68.17 922 9.18 2.40 -.02 9.19 2.39 -.11 64 K-2 240 .86 59.56 39.58 7.52 9.76 3.84 .58 9.01 3.6S 65 K-2 246 23.95 70.69 5. 36 4. 74 4. 74 1. 08 -. 00 4.74 1.42 .12 66A K-2 252 .32 49.26 50.42 8.00 8.31 2.53 .12 8.21 2.33 .10 66B F-2 15 .41 31.18 68.41 9.15 9.23 2.10 .04 9.20 1.86 .06 APPENDIX II (continued) SampleCoreDepth in Percentage Inman(1952 )* Folk and Ward (1957)* # # core(cm) Sand Silt Clay Median Mean Sorting Skewness Mean Sorting Skewness

67 F-2 83 .00 31 18 68,82 9.30 9.44 2.28 .06 9.39 2.02 :06 68 F-2 160 .00 26.99 73.01 9.32 9.31 2.01 -.01 9.31 1.81 -.01 69 F-2 240 .00 29.80 70.20 9.41 9.52 2.33 .05 9,49 2.14 .03 71 C-42 78 .13 47.09 52.78 8.17 8.55 2.10 .18 8.42 1.92 .16

72 C-42 83 1.27 93.50 5. 24 5. 36 5. 49 .84 . 16 5.45 1. 01 .28 73 C-42 88 15.23 81.49 3.29 4.61 4.85 .83 .29 4.77 .81 .38 74 C-42 93 .00 4404 55.96 8.42 8.68 2.30 12 8.59 2.19 .05 75 C-42 185 .63 41.48 57.89 8.51 8,49 2.35 -.01 8,50 2 12 -.01 76 C-42 200 9.61 85.65 4.74 4.98 5.11 .89 .I4 5.06 1.02 .28

77 C-42 208 74. 81 23.22 1.96 3.55 3. 55 . 65 .01 3 55 .72 .13 78 C-42 215 5.04 90 63 4,33 5.01 5. 16 .81 .19 5. 11 .87 .27

79 C-42 300 .15 49.87 49.97 7.96 8.36 2.20 .18 8.23 2.07 13 80 C-42 428 1.39 89.37 924 5.22 5.62 1,00 .41 5.49 1.43 .56 81 C-42 433 .01 46.26 53.73 8.26 8.65 2.78 .17 852 2.05 .18 82 C-42 506 .73 87.93 11.34 5.57 5.83 1.05 .25 5.74 1.40 .41 84 A-2 2 1.24 27.39 71.36 9.19 8.98 2.15 -.10 9.05 1.96 -.11

85 A-2 60 1. 51 50. 35 27.77 7. 77 8.44 2. 75 . 24 8.22 2. 59 19 86 A-2 55 15.53 56.71 27.77 5. 81 6.95 2.93 .39 6.57 2.75 .38

. 87 A-2 59 .65 51. 10 48. 25 7. 81 8.38 2. 37 . 24 8. 19 2.25 17 88 A-2 150 1.86 71.68 26.46 6.62 7,41 1.90 .42 7.15 1.95 .33 89 A-2 200 .37 33.16 66.46 9.38 9.46 2.86 .03 9.43 2.69 -.02 90 A-2 300 .07 48.56 51.37 8.07 8.55 2.19 .22 8.39 1.99 .20 94 A-32 44 .67 51.34 47.99 7. 80 8. 12 2.45 .13 8.01 2.29 .09 95 A-32 48 9.27 69.61 21.11 5.51 6.88 2,64 .52 6.42 2.70 .57

. 96 A-32 505 .35 45. 19 54. 46 8. 36 8. 76 2. 58 .16 8,62 2.42 10

97 A-32 111 1.03 59.73 37. 16 6. 74 7. 73 3. 04 . 33 7.40 2.75 ..34 98 A-32 115 66.04 24.00 9.95 3,71 4.29 1.20 .49 4.10 1.74 .62 99 A-32 121 .00 40.36 59.64 8.63 8.80 2.16 .08 8.74 2.02 .04 101 A-32 186 2.98 78.16 18,87 5.25 6.49 2.01 .62 6.08 1.98 .63 102 A-32 234 55.38 41.38 3.23 3.73 3.90 .69 .24 3.84 .81 .38 '.0 .19 103 A-32 310 .64 55.73 43.63 7.53 8,07 2. 58 .21 7.89 2.38 APPEWDIX II (continued)

SampleCoreDepth in Percentage Inman(19521 Folk and Ward(1957) _# # core (cm) Sand Silt Clay Median Mean Sortix,g Skewness Mean Sorting Skewness 104 A-32 430 .39 42.43 57.18 8.51 8.76 2.32 .11 8.68 2.10 .10

105 A-32 475 .22 47.63 52. 15 8. 14 8.48 2. 35 .15 8.36 2.22 .09 107 E-3 32 5.22 37.47 57.30 8.55 8.57 2.68 .01 8.56 2.57 -.06 108 E-3 85 .08 38.32 61.60 8.89 9.00 2.62 .04 8.96 2.45 -.00 109 E-3 195 .26 37.71 62.04 8.88 8.95 2.52 .03 8.93 2.38 -.02 110 E-3 300 .32 46.65 53.03 8.22 8.45 2.65 .09 8.37 2.42 .07 111 E-3 398 .75 51.53 47.90 7.78 8.21 2.87 .15 8.06 2.59 .15 112 E-3 430 9. 19 40.80 50. 01 7.97 8.00 3.42 01 7.99 3. 15 -.01

113 F-4 4 10 42. 78 57. 12 8.43 8. 62 2. 02 . 09 8.56 1.92 .04

114 F-4 125 .18 39.73 58. 34 8.51 8. 70 2. 04 . 09 8.64 1.77 .14 116 D-3 308 1.10 66.63 32.00 6.48 7.44 2.61 .37 7.12 2.40 .38 117 D-3 315 35,79 55.83 8.38 4.27 4.55 .96 .28 4,45 1.37 .47 119 D-3 403 .36 59.58 40. 05 7.22 7. 87 2.69 .24 7.65 2.49 .22 120 D-3 408 17.68 69.38 12.94 4.71 5.53 1.61 .51 5.26 2.02 .52

121 D-3 412 49. 12 47.31 3.57 4. 02 4. 09 .73 .10 4.07 1.00 .32

122 D-3 415 .57 49.94 49.48 7.92 8.43 2. 61 19 8.26 2.49 .84

123 D-3 470 1. 17 60. 13 38.70 7.07 7.86 2.60 . 30 7.60 2. 36 31 124 D-3 473 16,81 72.85 10.34 4.68 5.30 1.32 .47 5.10 1.74 .59 125 D-3 476 56.32 39.96 3.72 3.87 3.93 .67 .10 3.91 .93 .34 126 D-3 480 .69 45.85 53.47 8.20 8,28 2.26 03 8.26 2. 16 -.03 127 D-3 500 15. 57 70.40 14. 02 4. 84 5. 66 1. 64 50 5.38 1.97 .58 128 D-3 503 60. 58 36.37 3.05 3. 85 3. 89 57 07 3.88 .70 .28 129 D-3 509 26.61 57.86 12,53 4.49 5.22 1.47 .50 4.98 2.03 .63 131 B-3 15 .85 55.40 43.75 7.57 8.17 2.47 .24 7.97 2.42 .17 132 B-3 19 42.60 51.27 6,13 4.16 4.46 1.36 .22 4.36 1.58 .36 134 B-3 65 .05 59.50 40.45 7.40 8.00 2.32 .26 7.80 2.21 .21 135 B-3 68 .17 84,20 15.63 5.66 6.31 1.55 .42 6.09 1.79 .50 136 B-3 71 02 48.77 51.20 8.05 8.38 2.11 .16 8.27 1.91 .15

137 B-3 170 . 05 57. 10 42.85 7.56 8. 01 2. 17 .21 7.86 2.01 .18 141 D-4 2 2.88 28.78 68.33 9.06 8.99 2. 09 -. 03 9.01 2. 14 -. 15 0 142 D-4 107 4.15 89.58 6.27 5.07 5.55 1.09 .34 5.32 1.35 .48 APPENDIX II (continued) SampleCoreDepth in Percentage Inman(1952)* Folk and Ward(1957)* // # Core (cm) Sand Silt Clay Median Mean Sorting Skewness Mean Sorting Skewing

143 D-4 112 .07 48.14 51.79 8.12 8.73 2.30 27 8.53 2.11 .24 144 D-4 210 .00 42.46 57.54 8.43 8.46 2.08 .01 8.45 1,93 -.02 145 D-4 215 .30 68.99 30.71 6,39 7.29 2.51 .36 6.99 2.31 .37 146 D-4 218 .04 47.22 52.74 8.18 8.59 2.20 .19 8.45 2.04 .15

147 D-4 306 07 46.26 53.67 8.26 8.67 2.28 .18 8.53 2. 19 11 148 D-4 310 1. 10 80.90 18. 01 5.45 6.49 1.94 .54 6. 14 2.00 .58 151 A-2 387 .14 52.00 47.86 7.86 8.51 2.23 .29 8.29 2.03 .28 154 E-2 4 1.66 29.64 68.70 8.92 8.76 1.90 -.09 8,81 1.95 -.20 155 E-2 70 2.77 38.44 58.80 8.65 8.44 2.26 -.09 8.51 2.20 -.17 156 E-2 107 9.09 34.05 56. 85 8. 54 8. 31 3. 02 -. 08 8.39 3.86 -.30 158 E-2 200 11.96 35.21 52.83 8.22 7.95 3.35 -.08 8.04 5.62 .38 160 E-2 295 1.41 38.95 59.64 8.90 9.26 9.94 .12 9.14 2.77 .07 161 E-2 305 17.64 32.78 49.58 7.92 7.65 3.93 -.07 7.74 3.62 -.09 162 E-2 361 2.36 33.84 63.80 9.16 9.18 2.91 .01 9.17 2.79 -.06

164 E-2 587 2.63 37. 12 60.24 8. 89 8.96 3. 01 .02 8.93 2. 82 -.02 168 D-3 90 2.77 41.07 56.16 8.41 7.98 2.85 -.15 8.12 2.55 -.14 169 D-3 120 .06 28.70 71.24 9.29 9.26 2.17 -.02 9.27 1.99 -.04 170 D-3 190 .35 60.79 38.85 6.90 7.66 2.65 .29 7.41 2.41 .28 171 D-3 194 4.54 67.09 28.37 6.00 7.22 2.87 .43 6.81 2.64 .46 172 D-3 197 .43 41.00 58.57 8.59 8.84 2.20 .12 8.76 2.00 .11

173 D-3 245 .10 54.00 45.90 7.66 8.22 2.67 .21 8.03 2.46 .18 174 D-3 250 13.01 72.50 14.49 4.78 5.82 1.74 .60 5.47 2.06 .67 175 D-3 278 3.15 65.31 31.55 6.25 7.34 2.77 .39 6.97 2.52 .41 176 D-3 282 19.88 66.88 13.23 4.70 5.34 1.46 .44 5.13 1.94 .56

177 D-3 285 76. 11 20.32 3.57 3.81 3.90 .38 .22 3.87 .59 .40 178 D-3 290 .56 55.82 43.62 7.51 808 2.81 .20 7.89 2.56 .20 180 B-2 40 1.73 45.05 53.22 8.19 8.45 2.11 .12 8.36 1.99 .07 181 B-2 45 .43 49.43 50. 14 7.98 8.47 2.26 .22 8.31 3.14 .16

182 B-2 50 ,.88 63. 15 35.97 6.93 7. 75 2. 56 .32 7.48 2.39 .30 183 B-2 54 .20 47.83 51.96 8.11 8.45 2.20 .16 8.34 2.05 .11 184 B-2 132 .09 50.14 49.78 7.95 8.42 2.25 .21 8.27 2.12 .15 APPENDIX II (continued) )* 1957)* SampleCoreDepth in Percentage Inman(1952 Folk and Ward( # core (cm) Sand Silt Clay Median Mean Sorting Skewness Mean Sorting Skewness

185 B-2 135 4.58 77. 17 18.26 5.42 6. 38 2. 09 .46 6.06 2. 10 .53 187 F-2 337 1.00 45.48 54.51 8.33 8.79 2.28 .20 8.64 2.11 .17 188 F-2 435 .02 36.00 63.98 8.93 9.03 2.26 .04 9.00 1.98 .08 191 D-10 14 56.71 18.45 24.84 3.41 5.96 3.28 .78 5.11 2.93 .76 193 D-10 90 51.97 23.30 24.73 3.86 5.93 3.31 .63 5.24 3.03 .59 195 D-10 100 61.42 17.24 21.34 3. 10 5.63 3. 34 76 4.79 3. 13 .70 196 D-lO 110 84.93 5.39 9.69 2.89 3.11 .72 .30 3.03 1.51 .54 197 D-10 116 8.80 30.75 60.45 8.72 8.81 2.38 .04 8.78 2.55 -.12 198 D-10 119 41.86 24.26 33.88 6.35 6.50 3.86 .04 6.45 3.43 .07 199 D-10 122 87.45 6.05 650 2.81 2.90 .68 .15 2.87 1.52 .46 200 D-10 125 64.08 13.69 22. 33 2.80 5. 55 4. 05 .68 4.63 3.80 .67 202 D-10 135 52.13 22.80 25.07 3.23 5.38 3.95 .54 4.67 3.58 .51 203 D-10 142 67.57 13.65 18.77 1.90 3.99 4.57 .46 3.29 4.09 .49 205 D-10 154 50.44 25.88 23.68 3.95 5.76 3.28 .55 5.16 2.99 .52 206 D-10 157 67.15 15.05 17.80 2.95 5.21 3.22 .70 4.46 3.11 .69 207 D-10 160 47.82 31.03 21.15 4.11 5.74 3.35 .49 5.20 3.25 .45 208 D-10 163 82.50 9.54 7.96 2.30 3.09 1.31 .60 2.82 1.99 .69 209 D-10 166 82.27 9.16 8.58 .25 1.79 2.50 .62 1.28 2.88 .69 211 D-10 192 82.52 10.34 7. 14 2.71 3.04 1. 09 .30 2.93 2.07 .36 212 D-10 207 77.39 10.35 12.26 3.20 5.02 2.30 .79 4.41 2.43 .79 214 D-2 28 6.65 38.61 54.74 8.41 8.S4 2.97 .05 8.50 2.82 -.01 216 D-2 97 6.32 38.55 55. 13 8.42 8. 37 3. 05 -. 02 8.38 2.83 -.05 219 A-S 286 21. 16 46.00 32. 84 6. 18 7. 14 3. 35 .29 6.82 3. 06 .30

220 A-S 299 .01 11 81 88.18 10.25 10. 25 2. 03 . 00 10.25 1. 86 -.01

221 A-S 304 . .02 50.00 49.98 7.96 8.93 2.37 .41 8.61 2.16 .39 222 A-S 332 3.93 24.54 71.53 9.58 9.50 2.63 -.03 9.52 2.65 -.13 223 A-S 336 49.56 45.85 4.59 4.01 4.05 1.21 .04 4.04 1.41 .15 224 A-S 353 67.85 29.92 2.23 3.43 3.42 .94 -.02 3.42 1.01 .10

226 A-S 115 .36 45.46 54. 18 8.34 8.84 2.59 . 19 8.67 2.43 .14 227 A-S 122 3.25 85.65 11.09 5.32 5.62 1.11 .27 5.52 1.61 .46 228 A-5 135 .10 37.50 62.40 9S1 10.20 3.55 .19 9.97 3.19 .19 N) APPENDIX II (continued)

SampleCore Depth in Percentage Inman(1952) Folk and Ward(1957) # core (cm) Sand Silt Clay Median Mean Sorg Skewness Mean Sortiflg Skewness 229 A-S 237 1284 43,35 43.81 7.42 7,74 3.51 .09 7,64 3,18 .09 230 A-S 249 33,76 44.79 21.45 4.88 6.13 3.03 .41 5,72 2,96 .41 231 A-5 254 2,75 40.13 57. 12 8.61 8.91 2.79 .11 8,81. 2,66 .04 232 A-31 65 21.52 71,82 6.67 4.37 4.89 1.04 .50 4.72 1.4 .62 233 A-31 85 31,84 61.36 6.80 4,43 4.77 1.04 .33 4,65 1.37 .49 234 A-31 106 84.32 4,02 11,67 2,05 2,46 1,49 .27 2.32 3.50 .53 238 C-4 86 86.56 10.92 2,52 3,15 3.29 .56 .26 3.24 .65 .37 239 C-4 96 9. 16 80,77 10. 07 5, 16 5.45 1. 23 .24 5.36 1,55 .39 240 C-4 103 6S,83 29.04 2,13 3,76 3,77 .55 .01 3,76 .70 .18 241 C-4 145 .91 54.13 44,96 7.65 8.28 2.43 .26 8,07 2,29 .21 242 C-4 150 4,05 84,37 11,58 5.37 5,69 1.22 .26 5.58 1,57 .42

244 C-4 168 .36 36. 87 62. 77 8. 77 8. 88 2. 04 .06 8.85 1. 85 .04

250 A-4 150 6. 15 81.72 12. 13 5.30 5,51 1. 16 .18 5.44 1,74 .40 252 A-4 158 57,85 39,11 3.05 3.91 3.98 .55 .14 3,96 .83 .31 253 A-4 164 15,55 76.34 8,11 5.15 5.17 1.14 .02 5.16 L50 .25 254 A-4 172 .09 37.78 62,13 9.03 9,36 2.65 .12 9.25 2.4Y .08 256 C-3 50 .00 34.32 65.68 9,22 9,40 2.54 .07 9.34 2.39 .02 257 C-3 60 1.91 51,85 46.96 7.73 8,23 2,59 .19 8,06 2.45 .13 260 C-3 85 53.11 57,08 42.39 7,42 8.16 2,34 .31 7.91 2,21 .26 262 C-3 98 .46 44.05 55,49 8,37 8,78 2. 08 .20 8.64 2,03 10 263 C-3 197 .74 53.86 45.40 7.55 8.34 2.64 .30 8,08 2,47 .25 264 C-3 203 65,84 22.04 12,12 3.48 4.73 1.84 .68 4.31 2,21 .74 265 C-3 208 .65 38.47 60,88 8,81 9.03 2.42 .09 8.96 2,25 .05 266 C-3 270 .92 53,11 45.97 7,59 8.40 3.02 27 8.13 2.76 .25

267 C-3 274 68.30 27, 14 4.56 3 57 3. 70 . 72 .19 3,66 1. 10 .42 268 C-3 285 88.52 9.37 2,11 3,08 3.13 .57 .09 3.11 .65 .20 269 C-3 297 84,91 3.59 1,50 2.67 2.71 .44 .09 2,70 .52 .22 270 C-3 310 93.83 4,09 2.08 2.66 2.68 .54 .04 2.68 .62 .15 271 C-3 314 .23 43,44 56.33 8.60 9.13 2.89 .18 8.95 2.70 .14 272 C-3 420 .50 41.60 57.90 9.01 8.98 3,29 -.01 8.99 3.01 .-,03 273 C-3 425 40,58 45.57 13,85 4.19 4.91 1.99 .36 4.67 2.51 .51 APPENDIX II (continued) SampleCoreDepth in Perceng Inman(1952jL Folk and Ward (195fl /f # core (cm) Sand Silt C1y Median Mean Sg Skewness Mean Sorting Skewness

274 C-3 450 66.72 17.23 16. 05 3. 03 5. 17 2. 82 .76 4.46 2.91 .78 2.75 C-3 460 62.09 22.01 15.90 3.46 5,26 2.67 .67 4.66 2.61 .68 279 G-1 95 .51 45.52 53.97 8.30 8.57 2.63 .10 8.48 2.47 .05 280 c-i 98 15.89 63.38 20.73 5. 56 6.63 2.62 .41 6.27 2.63 .47 281 c-i 101 .47 30,90 68.63 9.04 9.05 1.94 .00 9.04 1.82 -.04 282 G-i 251 2.27 67. 15 30. 58 6.49 7.36 2. 54 .34 7.07 2.35 35

283 C-i 254 .55 45.80 53.65 8.22 8.32 2.23 .05 8.29 2. 12 -,01 286 G-1 369 1.49 60.28 38.23 7.24 7.76 2.30 .23 7.59 2, 15 .20 2.87 G-1 372 60.59 31.66 7.75 3.87 4.52 1.16 .56 4.30 1,54 .66 288 c-i 376 1.18 33.19 65.63 8.98 9.08 2.11 .04 9,04 2,03 -.02 289 G-i 32 .44 30,03 69,54 9.10 9,13 1.96 .01 9.12 1.79 -.01 290 -5 233 3. 10 48.80 48. 09 7.81 8.00 2.63 .07 7,94 2,43 .04 291 B-S 238 .20 42.19 57.61 8.57 8.99 2.27 .19 8.85 2.12 .14 292 B-S 337 11.35 49.93 38.71 6,78 7.50 3.35 .22 7.26 3,07 .20 293 B-S 340 .43 45.52 54.05 8.26 8.63 2.12 .17 8,51 1,91 .17 294 B-S 429 16.07 51.53 32.41 6.52 6.91 3.42 .11 6.78 3.21 .10 296 B-5 510 .11 37.99 61.90 8.89 9.18 2.35 .12 9.09 2.08 .15 297 A4A 149 1.55 65.58 32.87 6.77 8.07 2.54 .51 7.63 2.45 .47 298 A4A 157 32.69 55.02 12.39 4.62 5.28 1.85 .35 5.06 2.05 .45 300 A4A 170 .57 32.13 67.30 8.99 9.01 2.01 .01 9.00 1.84 -.01 302 A4A 247 1.79 70.71 27.50 6.22 7.32 2.61 .42 6.95 2.48 .43

304 A4A 257 .11 34.77 65. 12 9. 18 9.46 2.44 .12 9.36 2,22 ,ii 306 A4A 366 28,54 67.34 4.11 4.43 4.57 .93 .15 4.53 1.09 .30 308 A4A 383 50.33 39.58 10.09 4.00 4.66 1.09 .61 4.44 1,64 .72 309 A4A 390 .87 34.73 64.40 9.07 9.23 2.44 .07 9.18 2.28 .02 310 A4A 455 8.62 63.10 28.28 5.49 7.82 3.60 .65 7.04 3.44 .66 311 A4A 462 26.25 66.08 7.67 4.32 4.57 .91 .28 4.49 1.76 .53 312 B-S 52 .32 35.76 63.92 8.98 9.02 2,37 .05 9.OS 2.13 .05 314 B-S 133 .22 44.32 53,47 8.25 8.54 2.55 .11 8.44 2.37 .07 315 B-S 138 .31 29.46 70.23 9.24 9.06 2.32 -.08 9.12 2.09 -.08, 316 B-6 30 9.13 84.23 6.65 5,08 5.25 1.06 .16 5.19 1.36 .34 '4 APPENDIX II (continued)

SampleCore Depth in Percentage Inman(19525 Folk and Ward(1957) # # core(cmj Sand Silt Clay Median Mean Sorting Skewness Mean Sorting Skewness 317 B-6 44 16.27 78.03 5.70 4.55 4.78 78 .30 4.70 1.19 .47 318 B-6 49 1.21 39.13 59.67 8.64 8.75 2.27 .05 8.72 2.19 -.02

319 B-6 89 8. 15 68.74 23. 11 5.84 6. 70 2.48 .35 6.41 2.35 .39 320 B-6 93 57.98 38.78 3.24 3.85 3.64 .85 -.25 3,71 1.07 .00 321 B-6 98 .22 46.53 53.25 8.21 8.50 2.28 .13 8.40 2.11 .10 326 6509-9 98 .89 71.31 27.81 6,53 7.62 2.64 .41 7.26 2.56 .42 327 6509-9 106 18.20 79.59 2,21 4.58 4.84 .90 .29 4.75 .90 .36 328 6509-9 112 .92 45.19 53.89 8.38 9.03 3.01 .21 8.81 2.83 .16 329 6509-9 170 18.90 77.53 3.57 4. 58 4. 80 .90 25 4.73 1. 02 .32

330 6509-9 180 66.64 30.39 2.97 3.53 3. 66 .73 .18 3.62 .87 .33 332 6509-7 34 3.31 26.50 70,19 9.09 8.97 2.03 -.06 9.01 2.07 -.17 333 6509-7 43 73.95 23.85 2,20 3.34 3.44 .80 .13 3.40 .93 .24 334 6509-7 49 2.43 27.44 70.13 9.22 9.18 2.17 -.02 9.20 2.28 -.15 335 6509 -7 111 60 34.01 65.39 9.25 9. 37 2. 72 05 9.33 2.47 .03 336 6509-7 117 32.38 61.30 6.32 4.52 4.06 1,91 -.24 4.22 3.69 .22 337 6509-7120 .42 31.57 68,01 9.20 924 2.29 .02 9.23 2.14 -.02 339 6509-7184 13.42 78.60 7.97 5.00 5.27 1.20 .22 5.18 2.05 .46 340 6509-7192 72.85 25.31 1.85 2.41 3.08 1.20 .56 2.86 1.26 .59 341 6509-7213 13.64 68.96 17.40 5.37 6.22 2.12 .40 5.94 2.31 .42 342 6509-7236 42.28 51.98 5.74 4.18 4.12 1.38 -.04 4.14 1.67 .17

343 6509-7240 2. 13 37. 15 60. 72 8. 77 8,95 2. 38 .07 8. 89 2.33 -. 01 344 6509-4263 14.17 57.40 28.43 4.94 7.11 3.07 .71 6.39 2.82 .70 345 6509-4274 7.33 56.31 36.36 6.23 7.27 2.95 .35 6.92 2.65 .35 346 6509-4279 .35 27.69 71.96 9.40 9.37 2.24 -.01 9.38 2.05 -.03 347 6509-7398 4.82 54.03 41.15 7.22 7.88 3.24 .20 7.66 2.91 .23 348 6509-7404 17.43 7396 8.61 4.74 5.07 1.13 .29 4.96 1.65 .48

349 6509-7420 69.58 26.37 4.05 3.45 3.30 I. 18 - 12 3.35 1.37 .13 350 6509-7425 .40 34.33 65.27 9.09 9.25 2,35 .07 9.20 2.13 .06 351 6509 -4433 8.83 82 33. 35 6. 18 7. 32 3. 08 37 6.94 2.78 .39 352 6509-4438 40.26 54.45 5.29 4.18 4.24 .1.06 .06 4.22 1.42 .23 354 6509-7453 51.55 45.20 3.25 3.99 3.81 .44 -.40 3.87 .75 -.05 Ui APPENDIX II (continued) Inman(1952)* Sa#mPleCore Depth in Percentage Folk and WardLl957)* # core (cm) Sand Silt Clay Median Mean Sorting Skewness Mean Sorting Skewness

355 6509-4 465 83.84 15.27 1.40 2. 71 3. 16 .86 .53 3.01 1.04 . 62 356 6509-6 82 .40 24.30 75.30 9.31 9.26 1.79 -02 9.28 1.70 -.08 357 6509-6 100 .13 25.99 73.88 9.64 9.26 2.02 -.19 9,39 1.81 -.18 358 6509-6 113 .22 37.56 62.22 8,96 9.14 2.57 .07 9.08 2.33 .07 359 6509-6 118 40.42 55.13 4.46 4.22 4.15 1.50 -.05 4.17 1.56 .11 360 6509-6 130 82.23 17.52 .25 2.57 3.06 .97 .51 2.90 .90 .49 361 6509-6 137 .13 28.12 71.75 9.53 9.48 2.49 -.02 9.50 2.21 -.00 362 6509-6 198 .05 43.03 56.92 8.52 8.89 2.36 .16 8.77 2.13 .15 363 6509-4 205 2.55 94.58 2.87 4.76 4.81 .60 .09 4.79 .65 .24 364 6509-6 210 .64 51.84 47.52 7.76 8.34 2.51 .23 8.15 2.37 .17 365 6509-6 289 9.78 63.91 26.31 6.17 7.08 2.76 .33 6.78 2.70 .32 366 6509-6 295 31.98 57.27 10.75 4.60 4.91 1.90 .16 4.81 2.19 .30 371 6509-4 182 11.09 64.34 24.58 5.57 6.81 2.66 .46 6.39 2,53 .47 372 6509-4 209 33.52 53.14 13.34 4.27 5,15 1.87 .47 4,86 2.05 .53 374 6509-5 96 15.93 64.21 19.86 5.23 6.42 2.41 .49 6.02 2.41 .51 375 6509-5 104 83.96 11.65 439 3.16 3.33 .68 .25 3.27 1.13 .45 376 6509-5 109 2.33 33.33 64.34 8.83 8.62 2.26 -.09 8.69 2.23 -.17 377 6509-5 116 11.16 59.45 29.39 5.92 6.88 2.77 .35 6.56 2,53 .35

378 6509-5 124 45.87 46.76 7.37 4. 05 4.20 1. 12 .13 4. 15 1.55 .35 379 6509-5 130 89.28 8.16 2.56 2.76 2.96 .58 .34 2.90 68 .40 380 6509-1 39 83.47 14.01 2.52 3.45 3.39 .63 -.10 3.41 1.00 .20 381 6509-1 93 4.73 43.75 5152 8.08 8.07 2.51 -.00 8.07 2.37 -.05 382 6509-1 69 37.82 54.08 8.11 4.19 4.62 1.27 .34 4,48 1.99 .52

383 6509-1 76 73.79 22.67 3.54 3.60 3.55 .71 -.08 3.57 1. 10 .23 384 6509-1 84 48.54 44.98 6.49 4.02 4.25 1.06 .22 4.17 1.48 .40 385 6509-1 199 4.31 73.98 21.71 5.45 6.75 2.50 .52 6.32 2.42 .57 386 6509-1 154 45.43 51.93 2.64 4.05 4,06 .54 .03 4.06 .68 .27 387 6509-1 157 .44 40.54 59.02 8.63 8.80 2.36 .07 8.74 2.18 .04 393 6509-3 179 .50 35.20 64.30 9.04 9.28 2.32 .10 9.20 2,18 .06

394 6509-3 183 14.74 71.88 13.38 4.74 5.51 1.48 .52 5.25 1.83 .57 r., 395 6509-3 193 63.25 26.81 9.94 3.64 3.80 .90 .17 3.75 1.52 .45 396 6509-3 199 .80 35.76 63.43 9.07 9,22 2.65 .06 9.17 2.53 -.00 APPENDIX II (continued) (1952 )* 1957)* Sample Core Depth in Percentage Inman Folk and Ward( # core (cm) Sand Silt Clay Median Mean Sorting Skewness Mean Sorting Skewness 397 6509-3 223 31.04 61.37 7.59 4.45 4.71 1.13 .23 4.62 1.56 .40

398 6509-3 234 50.58 44.23 5. 19 2.99 4. 10 .76 .14 4. 06 1. 19 . 34 399 6509-3 245 57.22 37.62 5. 16 3.88 4. 05 .68 .26 4.00 1. 14 .43

401 6509-2 128 .11 26.44 73.44 9. 32 9. 29 1 99 -.02 9.30 1.82 -.03 404 6509-2 270 60.99 22.75 16.26 3.86 5.68 2.36 .77 5.07 2.38 .78 405 6509-2 275 .69 24.72 74.59 9.69 9.65 2.41 -.01 9.66 2,20 -.03 406 6509-2 322 6.64 84.34 9.02 5.06 5.33 1.09 .25 5.24 1.47 .42 407 6509-2 327 85.29 12.37 2.35 2.68 3.04 .85 .41 2.92 1.07 .51 408 6509-2 346 92.11 4.57 3.32 2.45 2.49 .63 .07 2.48 1.13 .35 409 6509-16 0 .70 18.81 80.49 9.53 9.52 1.75 -.01 9.52 1.59 -.01 409a6509-16 6 .41 18.18 81.41 9.75 9,75 1.94 -.00 9.75 1,81 -.04 410 6509-16 89 1.02 81.44 17.53 5.94 6.66 1.67 .43 6.42 1.84 .47 411 6509-16 97 23.28 52,82 23.90 6.20 6.53 2.72 .12 6.42 2.52 .19 412 6509-16 101 1.10 35.75 63.15 9.08 9.13 2.84 .02 9.11 2,69 -.04 413 6509-16 142 .24 95.52 4.24 4.98 5.12 .82 .17 5.07 .91 .32 414 6509-16 147 51.56 42.76 5,67 3.97 4.23 .81 .32 4.14 1,26 .50 415 6509-16 158 50.30 47.79 1.91 3.99 4.11 .95 .12 4,07 .97 ,19 416 6509-16 162 1.04 48.98 49.98 7.96 8.69 2.86 .26 8,45 2.65 .22 417 6509-16 204 77.64 20.59 1.77 3.22 3.07 1. 11 -. 14 3. 12 1.22 .06 419 F-3 15 .72 36.99 62.29 8.89 9.06 2.39 .07 9.01 2.33 -.01 420 F-3 27 1.36 34. 12 64.53 8. 89 8.83 2. 21 -.02 8.85 2,03 -. 04 423 F-3 44 35.52 5.86 3,55 -1.67 -1.65 4.54 .01 -1,66 4,41 .08 424 E-7 1 1.86 32.22 65.92 8.99 8.94 2.34 -.02 8.96 2.24 -.12 425 E-7 5 62.30 25.56 12.14 3.48 4.83 2.09 .65 4.38 2.23 .70 426 E-7 22 44.33 38.79 16.88 4. 15 5. 70 2. 51 .62 5. 19 2. 53 .65 427 E-7 29 3.43 44.25 52.32 8.22 8.70 3.22 .15 8.54 3.02 .10 428 E-7 33 40.77 41.81 17.42 4.16 5.88 2.70 .64 5.31 2.93 .70 429 E-7 36 7.14 38.58 54.28 8.30 7.97 2.98 -.11 8.08 2.72 -.12 430 PA-2 0 .20 26.80 73.01 9.28 9.25 1.98 -.02 9.26 1.80 -.02 431 PA-31 0 .44 24.28 75.28 9,45 9.49 1.96 .02 9,48 1.85 -.03 t'J

432 PA-32 0 .43 28.47 71. 10 9.25 9. 15 2. 17 -.05 9. 18 2.00 . 07 APPENDIX II (continued) )* 1957)* Sample Core Depth in Percentage Inman(1952 Folk and Ward( # # core (cmLSand Silt Clay Median Mean Sorting Skewness Mean Sorting Skewness 433 PA-4 0 .64 24.48 74.88 9.25 9.24 1.77 -.01 9.25 1.64 -.03 434 PA-5 0 .57 22.60 76.83 9.31 9.07 1.96 -.13 9.15 1.76 -.12 435 PB-2 0 2.36 25.75 71.88 9.08 8.85 1.95 -.12 8.92 1.89 -.18 436 P8-3 0 .75 26.73 72.51 9.33 9.28 2.10 -.02 9.30 1.93 -.04 437 PC-4 0 .43 21.80 77.77 9.61 9.61 2.01 -.00 9.61 1.84 -.02 437aPC-4 6 .56 19.32 8011 9.52 9.50 1.77 -.01 9.51 1.64 -.04 438 PC-42 0 .79 22.78 76.43 9.58 9.57 2.08 -.00 9.57 1.92 -.03 439 PD-2 0 1.72 34.01 64.27 9.06 9.26 2.40 .09 9.20 2.23 .05 443 PD-b 0 .34 36.06 53.10 8.22 7.89 3.10 -.10 8.00 2.91 -.13 444 PD-3 0 10.84 27.19 72.47 9.19 9.30 1.78 .04 9.23 1.68 -.01 445 PF-2 0 .62 30.93 68.45 8.98 9.00 1.86 .01 9.00 1.71 -.02

446 PF-3 0 .66 44.82 54.52 8.28 8.53 2. 12 .12 8.45 2. 10 .01 447 PE-2 0 .40 37.99 61.62 8.75 8.91 2.14 .07 8.85 1.92 .08 449 PE-3 0 .23 30.42 69.35 9.19 9.33 2.03 .07 9.28 1.83 .07 450 PE-4 0 .36 24,25 75.39 9.38 9.36 1.91 -.01 9.37 1.74 -.02 451 PE-7 0 .38 27.31 72.31 9.33 9.30 2.11 -.01 9.31 1.96 -.05 452 PF-4 0 .50 29.99 69.51 9.14 9.13 2.07 -.01 9.13 1,97 -.06 453 PA4B 0 .38 23.20 76.41 9,52 9.55 1.98 .01 9.54 1.81 -,00 454 PA4A 0 1.71 72.22 26.07 5,82 7.24 2.91 .49 6,77 2.74 .53 455 PA4A 6 .30 33, 10 66.60 9. 15 9. 14 2.44 -.00 9, 14 2. 18 .00 456 PB-4 0 .52 18.31 81,17 9,65 9.65 1.84 -.00 9.65 1.70 -.03 457 PC-2 0 .38 27,75 71.87 9.27 9.26 2.03 -.00 9.26 1.86 -.02 458 PC-3 0 .51 20.51 78.98 9,60 9.55 1,97 -.02 9.57 1.81 -.05 459 P6509-i 0 .60 44,78 54.62 8.29 8.55 2.13 .12 8.46 2.10 .02 460 P6509-2 0 .41 35,89 63.67 8,84 8,90 2.11 .03 8.88 2.11 -.07 461 P6509-3 0 .47 21,68 77.85 9,43 9.36 1.86 -.04 9.39 1,74 -.08 462 P6509-S 0 .32 34,76 64.92 8,98 9.29 2.59 .12 9.19 2.34 .11 463 PB-S. 0 .41 26.59 73.01 9.48 10.03 2.91 .19 9.85 2.79 .11 464 P8-6 0 .88 15.81 83.31 9.63 9.52 1.60 -.07 9.56 1.48 -.09 465 pG-i 0 .40 28.14 71.45 9.39 9.32 2,18 -.03 9.35 1.97 -.04 466 P6509-4 0 .37 24.96 74.68 9.53 9.49 2.06 -.02 9.50 1.84 -.01 oz APPENDIX II (continued) Sample CoreDepth in Percentage Inman ( 1952 Folk and Ward ( 1952_ # # core (cm) Sand Silt Clay Median Mean Sorting Skewness Mean Sorting Skewness 467P6509-6 0 .59 18.32 81.09 9.63 9.51 1.71 -.07 9,55 1.74 -.18 468 P6509-7 0 1.73 21.99 76.27 9.41 9.07 1.54 -.22 9.18 1.41 -.24 469 P6509-8 0 .45 21.11 78.43 9.53 9.20 1.57 -.21 9,31 1.44 -.23 470P6509-9 0 1.13 20.55 78.32 9.49 9.33 1.75 -.09 9.38 1.63 -.12 471 P6509-16 0 .68 21.98 77.34 9.47 9,24 1.71 -.13 9.31 (.56 -.15 472 PK-1 0 .39 21.88 77.74 9.55 9.29 1.72 -.15 9,38 1.55 -.15 473 PK-2 0 .40 18.95 80.65 9.73 9.54 1.74 -.13 9,58 1.59 -.14 474 F-3 55 21.95 4.02 3.05 -2,01 -1.75 1.91 .14 -1.84 2,47 .35 475 E-4 600 84.95 9.64 5,41 2.99 3.22 .70 .33 3.15 1.30 54

* Statistical parameters of these investigators based on calculations in the phi units( 4 = - in inches)

N) APPENDIX III COMPOSITION OF SAND FRACTIONS (Values given as number percent of sand fraction) Sample % Detritala Authieni< Biogeni Grains Io. Sand p H M Rx V Y Total G Py Total P B D R F Po 0TotalCounted

1 .73 5 Tr 3 3 11 1 1 3 2 16 63 4 Tr Tr 88 357 2 .41 4 3 18 24 11 55 8 2 66 301 3 .73 Tr Tr 2 50 53 4 4 35 3 2 47 311 4 6 1 88 95 0 2 3 5 100 5 [.02 3 Tr 2 43 48 7 32 11 Tr 1 52 3(Y? 6 .45 Tr 2 53 56 7 8 29 I 44 302 7 15.06 9 2 2 81 95 Tr 5 5 300 8 .48 4 1 3 35 42 9 36 11 Tr 2 58 306 9 .33 8 1 20 24 13 66 Tr Tr 2 12 15 1 4 34 336 10 1.00 16 1 14 14 7 52 Tr 1 16 29 Tr Tr 46 311 11 .41 2 Tr 14 8 3 27 3 3 5 4 59 4 Tr 72 273 12 23.04 49 9 38 8 Tr 99 Tr 1 2 280 13 1.02 35 5 11 34 3 88 1 1 1 8 9 291 14 .24 8 2 30 12 5 57 2 Tr 3 9 42 1 Tr 57 261 15 .90 7 2 45 10 6 Tr 70 Tr Tr Tr 27 1 28 314 16 .17 26 3 13 21 4 67 4 4 25 1 1 35 192 17 .08 4 26 1 31 6 Tr 14 2 45 1 68 327 18 .85 11 2 44 9 4 70 Tr Tr 29 Tr Tr 29 301

19 .19 4 27 21 52 4 3 40 1 48 277

20 .12 4 1 22 2 29 1 1 68 1 1 72 203 21 .88 26 Tr 42 11 3 Tr 82 Tr Tr 15 1 I 17 205 22 .00 3 Tr 35 2 1 41 3 Tr Tr 53 Tr 56 292 23 .08 3 40 3 2 48 Tr Tr 2 Tr Tr Tr 47 Tr 49 302 24 5.70 56 8 11 22 Tr 97 Tr 2 Tr 3 300 25 1.65 23 5 18 22 21 Tr 89 Tr Tr Tr 2 6 Tr 8 296 26 1.24 Tr Tr Tr 54 4 11 15 2 Tr 5 99 338 27 .31 13 2 56 3 4 78 Tr Tr Tr 20 Tr 22 358 28 24.32 30 21 10 35 3 Tr 99 Tr Tr Tr Tr 1 331 APPENDIX III (continued)

Sample % Detrital a Authigen&' iogen Grains No. Sand 0 H M Rx V Y Total G Py Total P B D R F Pc 0TotalCounted

29 .50 5 1 3 1 11 61 2 8 14 1 Tr 3 90 352 30 .23 7 1 8 4 20 7 7 42 7 Tr 13 5 Tr 5 72 352 31 13 3 1 62 4 Tr 71 1 1 Tr Tr 27 Tr 30 416 32 45.31 56 16 3 23 2 Tr 99 Tr Tr Tr 342 33 .04 7 2 57 3 1 69 Tr Tr Tr 2 23 1 4 31 404 34 .65 Tr Tr 6 Tr 8 3 3 74 3 Tr 5 2 Tr 1 89 319 35 .00 Tr Tr 45 5 Tr 51 Tr Tr 27 2 3 15 Tr Tr 49 406 37 .05 2 2 56 Tr Tr 61 2 2 26 2 2 1 5 Tr 1 37 326 38 .52 Ti' 38 Tr Ti' 40 Tr Tr 44 2 2 3 8 Tr 59 324 39 .02 Tr 50 Tr 51 3 3 16 1 Tr Tr 26 1 1 46 420 40 .04 Tr Ti' 67 Tr 67 4 4 13 4 1 10 Tr 29 352 41 .17 10 Tr 47 6 3 66 2 Tr 2 Tr 29 Tr 34 341 42 .00 9 1 50 Tr Tr 61 Tr Tr 18 2 Tr 3 14 Tr Tr 39 404 43 .81 1 20 Tr Tr 22 1 1 70 1 Tr Tr 4 Tr Tr 76 428 44 .25 18 2 66 8 Tr 94 2 2 Tr Tr 4 Tr Tr 5 482 45 .08 7 Ti' 70 6 Tr 85 2 2 2 Ti' 10 13 370 48 .63 14 6 53 19 4 96 Tr Tr 3 Tr 3 391 50 .00 2 2 76 2 86 2 2 Tr 12 12 343 51 .45 1 1 20 Tr Tr 23 4 4 53 2 Tr 10 7 Ti' 1 73 402 53 1.38 3 Tr 2 1 91 97 Ti' 1 1 Tr Tr 3 490 54 .32 Ti' Tr 95 96 1 3 Tr 4 421 55 1.47 17 1 17 20 8 62 Ti' Ti' 1 Tr Ti' 6 11 16 Tr 3 37 352 57 11.91 47 10 6 30 2 96 1 Tr Tr 2 4 368 58 .00 11 1 56 5 1 73 4 4 2 Tr 1 2 15 1 Ti' 23 496 59 .00 Tr 55 55 3 3 12 1 4 2 21 1 Tr 42 466 61 1.52 5 2 7 10 72 96 Tr 2 1 Tr 4 341 62 54.74 60 10 8 26 Tr Tr 100 348 63 3.25 54 9 2 23 3 98 Tr Tr Ti' Ti' Tr 2 368 64 .86 22 5 23 15 Tr 65 5 1 1 1 25 1 Tr 35 494 65 23.95 44 10 11 32 Tr 2 99 Tr Tr Tr Tr Tr 424 66A .32 2 Tr 69 5 Tr 77 Tr Tr 7 2 12 1 22 387 APPENDIX III (continued) Sample % Detritala Authigeniçb BiogenjC Grains No. Sand 0 H M Rx V Y Total G PyTotal P B D R F Po 0TotalCounted.

66B .41 15 Tr 8 5 3 31 Tr Tr Tr Tr 11 43 10 1 2 69 431 67 .00 7 42 2 Tr 51 2 2 21 Tr 7 4 2 Tr 47 637 68 .00 6 Tr 3 2 20 Tr 4 4 44 7 1 8 13 2 Tr 75 385 69 .00 Tr Tr 17 Tr 18 22 22 37 6 Tr 7 10 Tr 60 442 71 13 4 28 Tr 34 Tr Tr 40 2 Tr Tr 19 1 3 65 349 72 1.27 10 2 47 36 3 Tr 98 Tr Tr Tr Tr 1 582 73 15.23 58 7 3 30 1 Tr 100 Tr Tr 469

74. .00 7 29 2 39 Tr Tr 29 4 Tr 12 14 2 61 350 75 .63 Tr 14 1 16 Tr Tr 42 4 2 16 10 Tr 8 83 293 76 961 38 23 30 2 1 98 Tr Tr Tr Tr 1 439 77 74.81 61 10 2 28 Tr 100 372 78 5.04 48 4 20 26 2 100 349 79 15 5 Tr 59 6 Tr 70 2 2 19 Tr Tr Tr 8 Tr 28 489 80 1.39 13 7 62 13 3 97 Tr 2 3 416 81 .01 4 Tr 76 1 81 Tr Tr 3 Tr 1 13 Tr 2 19 420 82 .73 17 9 68 6 2 96 Tr Tr 4 Tr 4 405 84 1.24 8 1 3 7 Tr 20 Tr Tr 1 1 20 16 5 1 35 80 616 85 1.61 6 1 10 3 57 77 Tr Tr Tr Tr 5 8 9 Tr Tr 22 590 86 15.53 20 3 2 16 55 92 Tr Tr 1 3 Tr Tr 4 289 87. 65 3 Tr 8 Tr 57 70 Tr Tr Tr 5 6 15 2 2 30 325 88 1.86 2 2 3 8 82 96 Tr Tr Tr Tr 3 Tr 4 395 89 .37 18 3 43 6 Tr 71 Tr Tr 9 Tr 4 3 10 Tr 1 29 431 90 .07 Tr Tr 36 1 38 11 11 7 Tr Tr 44* 52 533 94 .67 10 4 36 10 1 61 Tr Tr 1 1 7 25 22 1 2 39 521 95 9.27 25 6 17 42 Tr 90 Tr Tr Tr Tr Tr Tr Tr 8 Tr 10 363 96 35 10 2 28 6 Tr 46 Tr Tr 3 2 14 10 18 Tr 7 54 421 97 1.03 40 6 15 34 Tr 95 Tr 1 Tr 3 Tr 5 389 98 66.04 56 11 2 30 Tr 98 Tr Tr Tr 2 360 99 .00 6 4 36 2 47 Tr Tr 29 2 Tr 10 11 Tr 53 530 101 2.98 32 7 24 34 Tr 2 99 Tr Tr Tr Tr Tr 500 102 55. 38 58 12 2 27 Tr Tr 100 Tr Tr 372 t'.) APPENDIX III (continued)

BiogencC Sample °/ Detritala Aueniç Grains No. Sand p H V Y Total C Total P B D R F Po 0 TotalCounted

103 .64 23 5 41 15 1 Ti' 86 5 5 Ti' 9 Ti' 10 651 104 .39 33 5 20 34 1 92 1 1 3 Ti' Tr 2 7 232

105 .22 16 4 51 19 Ti' Ti' 89 2 Ti' 8 Ti' 11 466 107 5.22 37 10 11 30 Ti' Ti' 88 Ti' Tr Tr Ti' 2 4 4 Tr Ti' 12 450

108 .08 Tr Ti' 59 1 Ti' 63 Tr Ti' Tr Ti' 34 Ti' 2 38 311 109 .26 10 2 56 8 Ti' 77 1 1 Ti' Tr 20 1 Ti' 22 421 110 .32 29 2 53 4 89 Ti' Tr Tr 11 Tr 12 484

111 .75 20 1 61 Ti' 91 Ti' 9 Tr 9 362 112 9. 19 58 8 5 25 1 Ti' 99 Ti' 1 1 356

113 . 10 30 3 35 19 Ti' 87 1 1 4 6 1 12 286 114 , 18 53 1 54 5 5 23 Ti' Ti' 17 Ti' 41 403 116 1. 10 16 51 16 3 2 90 Ti' 10 Tr 10 290 117 35.79 51 9 7 31 Tr 1 99 Ti' Ti' Ti' Ti' Tr 301

119 .36 7 3 64 14 1 Ti' 90 Ti' Ti' Ti' Ti' 8 1 10 482 120 17.68 50 8 5 36 Ti' Ti' 99 Ti' Ti' 334 121 49. 12 53 14 6 27 Ti' 2 100 346 3* 122 .57 4 54 9 Ti' Ti' 72 Ti' Ti' 13 Ti' Ti' 10 26 347 123 1, 17 14 2 60 17 Ti' 1 95 5 5 257 1.4 16.81 35 4 15 42 3 Ti' 100 280 125 56.32 52 12 4 31 Ti' 1 100 Ti' Ti' 508 126 .69 10 3 40 25 1 1 81 15 Ti' Ti' 4 19 288

127 15.57 47 3 13 36 Ti' Ti' 100 Ti' Ti' 530

128 60.58 54 10 3 30 Ti' 3 100 304 129 26.61 50 9 10 30 Ti' Ti' 99 Ti' Ti' 434 131 .85 22 2 54 7 1 86 4 Ti' Ti' 8 Ti' 14 373 132 42.60 63 5 13 18 Ti' 99 Ti' Ti' 350

134 .05 Ti' 2 71 73 Ti' Ti' Ti' Ti' 24 3 Ti' 25 344 135 , 17 88 3 91 9 Ti' 10 370

136 , 02 Ti' Ti' 76 5 83 Ti' Ti' 17 18 428

137 .05 Ti' Ti' 67 3 71 1 1 Ti' Ti' 26 Ti' Ti' 28 448 141 2.88 17 2 7 19 5 50 3 Ti' 7 34 4 Ti' 2 50 476 APPENDIX III (continued) Sample % Detritala Authigeni Biogenit Grains Sand 0 H M Rx V Y Total G Pv. Total P B D R F Po 0 TotalCounted

142 4. 15 43 4 31 20 1 1 98 2 2 398 143 .07 Tr Tr 82 Tv 83 Tr Tr Tr 14 2 17 338 144 .00 Tr Tv 86 Tr 88 Tr Tr Tr Tv 10 Tr Tr 11 564 145 .30 92 92 Tr Tr 8 8 279 146 .04 Tv 56 Tr 56 Tr Tr 8 Tr 1 32 Tv 1 44 825 147 .07 Tr 75 Tr 75 Tv Tr Tr 23 Tr 24 284 148 1. 10 21 1 71 3 Tr 97 Tr 3 4 510 151 .14 9 Tr 32 3 45 34 34 16 Tr 4 Tr 21 429 154 1.66 16 2 7 13 Tr 39 Tr Tr Tr 15 30 9 4 2 61 382 155 2.77 21 4 3 13 38 79 4 4 1 5 10 1 Tv 17 300 156 9.09 52 5 10 29 Tv Tv 96 Tr Tv Tv 3 3 475 158 11.96 31 3 23 25 Tr Tr 83 Tv Tv Tr 16 Tr 16 287 160 1.41 36 1 21 33 Tr 91 9 1 10 414 161 17.64 44 3 12 37 Tr Tv 98 3 Tv 3 335 162 2.36 49 3 14 31 97 Tv Tv 3 3 314 164 2.63 35 3 21 28 Tv 88 13 13 272 168 2.77 30 2 24 32 1 Tv 89 Tv Tr Tv 1 1 Tv 2 6 11 421 169 ,. 06 3 Tr 24 Tv Tr 28 15 3 26 10 12 3 4 72 451 170 .35 3 2 75 3 1 84 Tv Tv Tv Tr 13 1 Tv 16 394 171 4.54 17 5 34 41 1 Tr 98 Tv Tr 1 Tv Tv Tv 316 172 .43 2 8 Tv 10 Tv Tv 48 5 24 10 2 89 297 173 10 2 3 72 7 Tv 85 2 2 Tv 12 Tv 14 362 174 13.01 24 3 25 35 2 2 97 Tv Tr Tv 2 Tv 3 360 175 3. 15 26 4 31 33 1 1 97 3 Tv 4 377 176 19.88 34 4 8 50 2 2 99 Tr Tv Tv Tv 431 177 76. 11 46 6 3 44 Tv 1 100 Tv Tv 432 178 .56 5 3 67 15 Tv 2 93 Tv Tv 1 Tv 6 Tv 8 305 180 1.73 28 3 9 16 56 Tv Tv 3 2 40*44 347 35* 181 43 3 48 Tv 52 2 2 4 Tv Tv Tv 6 Tv 47 770 182 .88 1 Tv 69 10 Tv 81 11 11 8 8 318 t\ 183 .20 1 48 2 Tr 55 10 10 8 1 Tv 4 21* 35 322 APPENDIX III (continued) Sample % Detrital a Authigeni' Biogenié Grains No. Sand p H M Rx V Y Total G PyTotal P B D R F Po 0TotalCounted

184 .09 Tr Tr 73 1 Tr 77 5 5 7 Tr 2 9 18 461 185 4.58 45 Tr 43 1 2 99 3 3 Tr Tr Tr 400 187 1.00 60 60 Tr Tr 13 1 1 24 Tr Tr 40 902 188 .02 37 37 6 6 19 2 Tr 4 20 2 10 57 457 191 56.71 46 8 4 36 Tr 94 2 2 Tr Tr Tr 3 4 333 193 51.97 39 5 2 45 6**Tr 97 2 2 Tr Tr Tr Tr 2 335 9** 195 61.42 33 4 5 28 78 2 Tr 2 Tr 17 Tr 2 19 342 196 84.93 47 7 1 42 1 99 1 1 473 197 8.80 17 1 6 23 18** 65 1 1 Tr 1 9 10 5 2 7 34 399 198 41.86 44 6 Tr 44 98 1 1 Tr Tr Tr 1 330 4**3' 199 87.45 39 8 2 44 97 Tr Tr Tr 2 Tr 2 349 200 64. 08 38 2 2 34 7 Tr 83 1 1 Tr Tr 14 1 16 393 202 52. 13 23 3 Tr 20 13** 59 1 1 2 Tr Tr 1 37 Tr 39 405 203 67.57 33 2 1 37 20** 92 31 Tr 4 Tr' 2 2 4 347 205 50.44 22 4 1 18 53' 98 Tr Tr 1 Tr Tr Tr 1 367 206 67.15 29 3 2 23 38** 96 1 Tr 2 2 2 315 207 47.82 26 3 Tr 32 31** 93 1 Tr 2 Tr Tr 4 1 5 436 9** 208 82.50 38 7 3 40 95 2 Tr 2 Tr 2 2 4 386 209 82.27 27 4 1 48 10 90 2 Tr 2 1 3 4 8 303 211 82.52 47 10 2 67 Tr 98 1 Tr 2 366 212 77.39 48 7 2 40 Tr 98 Tr Tr 1 Tr Tr 292 214 6.65 45 3 18 22 1 89 Tr Tr Tr Tr 10 10 365 216 6.32 51 3 10 33 Tr Tr 98 Tr Tr 1 1 470 219 21. 16 59 3 18 28 Tr 98 Tr Tr 1 Tr 2 294 220 .01 5 Tr 6 1 13 2 Tr 2 6 76 2 87 494 221 .02 1 Tr 51 Tr 53 15 Tr 31 Tr 47 675 222 3.93 51 3 13 28 Tr 95 5 5 337 223 49.56 60 8 3 28 100 336 224 67.85 66 15 1 18 100 Tr Tr 467 226 .36 8 1 26 5 39 Tr 6 4 50 1 Tr 61 401 227 3 25 32 2 35 26 Tr Tr 95 Tr Tr Tr Tr 1 1' Tr Tr 5 380 ji APPENDIX III (continued) Sample % Detrital Autlni_ Biog Grains No. Sand p H M Rx V Y Total G Pylta1 P B D R F PoOTotal Connted

228 10 4 Ti' 37 2 Tr 44 Ti' 2 3 49 2 Tr 56 394 229 12.84 62 S 7 24 98 Ti' Ti' Ti' 1 2 539 230 33.76 65 6 3 25 Ti' 99 Tr Ti' Tr Ti' Tr 328 231 2.75 58 3 8 28 Ti' 98 3 3 474 232 21.52 52 4 12 29 1 98 1 1 Tr Tr 298 233 31.84 61 7 6 26 100 Ti' Ti' Ti' 528 234 84.32 55 8 Ti' 36 100 363 238 86.56 67 14 19 Ti' Tr 98 Ti' Ti' 298 239 9. 16 56 3 25 16 Ti' 100 Ti' Ti' 347 240 68. 83 69 14 3 13 Ti' Tr 100 Ti' Tr 288 241 .91 24 2 33 16 1 Ti' 76 Tr 1 2 8 Ti' Ti' 5 7 Tr Ti' 22 461 242 4.05 19 3 46 25 1 1 94 Ti' 1 2 Ti' Ti' 4 4 315 244 .36 22 5 9 10 Ti' 46 4 4 38 2 6 6 50 330 250 6. 15 61 5 13 20 Tr 99 Ti' Ti' Ti' 302 252 57.85 73 9 18 100 Ti' Tr Ti' 367 253 15.55 61 5 7 26 Ti' 100 Ti' Tr 311 254 .09 35 4 34 13 85 Ti' Ti' 15 15 472 256 .00 6 Ti' 7 7 25 46 Ti' Ti' 7 Tr 5 35 6 Ti' 2 54 368 257 1.91 1 Ti' 6 3 69 79 Ti' Ti' 2 Ti' Ti' 2 16 Tr Ti' 20 455

260 53.11 Ti' Ti' 5 Ti' 68 74 Ti' Ti' Ti' Ti' 2 19 2 Ti' 26 345 262 .46 4 Tr 19 4 14 42 Ti' Ti' Tr 8 19 28 12 Ti' 58 331

263 .74 5 Ti' 45 8 2 60 Ti' Ti' Ti' Ti' 3 4 30 1 Ti' 39 308 264 65.84 52 8 2 35 Tr 97 Ti' Ti' Ti' Ti' 2 Ti' 2 409 265 .65 18 2 9 2 32 Ti' Ti' 6 2 10 34 13 2 1 68 291 266 .92 26 2 34 17 Ti' 79 1 1 3 Ti' Ti' 4 11 Ti' Ti' 20 414 267 68.30 53 7 5 35 Ti' 100 Ti' Ti' 320 268 88.52 56 6 2 35 100 346 269 94.91 54 8 1 37 Ti' 100 Tr Ti' 334 270 9383 50 15 35 Ti' 100 Ti' Ti' 278 271 23 2 1 48 2 Ti' 53 Ti' Ti' 10 3 31 2 Ti' 46 313 0' 272 .50 7 1 61 6 Ti' 76 1 1 2 21 Tr Ti' 24 301 APPENDIX UI (continued)

BlogerncC Sample l Detrital a Athgeni Grains No. Sand p H M Rx V Y Total C y_Total P BD R F Po 0TotalCowited 273 40.58 52 7 6 33 36 99 Ti' Ti' Tr Tr Ti' 309 274 6.72 50 8 2 40 Ti' 100 304 275 62.09 52 8 7 29 1 Tr 97 Ti' Tr 2 2 286 279 .51 9 2 32 8 2 52 Tr Ti' 1 Tr 3 6 30 3 5 47 420 280 15.89 40 7 11 27 1 Ti' 86 Ti' Ti' Ti' Ti' 2 2 6 1 1 13 364 281 .47 9 1 10 6 Ti' 27 Ti' Ti' 7 3 10 47 5 Ti' 1 72 433 282 2.27 29 49 14 Tr Tr 96 2 2 Ti' Ti' Ti' Ti' 2 369 283 .55 2 83 1 86 Tr Ti' 11 Tr Ti' 2 14 496 286 1.49 7 Ti' 64 6 79 2 2 4 Tr Ti' Tr 13 1 20 443 287 60.59 53 6 3 35 Ti' Ti' 97 1 Ti' 2 Ti' Tr 1 321 288 1.18 18 1 18 14 Tr 51 4 4 31 Tr Ti' 9 2 Ti' 1 45 504 289 .44 12 Ti' 11 11 16 51 7 2 5 4 3 1 49 378 290 3. 10 5 1 12 8 53 Ti' 79 6 Tr 6 Ti' Ti' Tr 12 1 1 15 419 291 .20 Ti' Ti' 8 2 9 19 9 9 21 26 13 Ti' 11 71 343 292 11.35 Ti' Tr 3 5 65 74 1 1 Tr Ti' 24 Ti' Ti' 25 492 293 .43 Tr 5 Ti' 11 17 28 28 2 Ti' 9 17 25 1 Ti' 56 483 294 16.07 10 2 4 19 53 88 Ti' Ti' 2 11 11 331 296 .11 Ti' 18 Ti' 1 20 1 1 24 Ti' 50 4 Tr 79 357 297 1.55 6 Ti' 10 5 53 74 2 2 2 Tr 21 Ti' Ti' 24 336 298 32.69 12 2 8 13 60 96 3 3 Ti' Tr 1 2 265 300 .57 24 6 5 17 5 Ti' 57 Tr Tr 2 10 21 8 Tr Ti' 42 384 302 1.79 Ti' Tr 39 9 2 56 Ti' Ti' Ti' Ti' Ti' 4 3 35 1 1 44 414

304 .11 6 Ti' 7 6 20 2 2 3 Ti' 13 39 12 Ti' 10 78 298 306 28.54 56 6 4 32 98 1 Ti' 1 Ti' Ti' 1 299 308 50.33 49 5 5 37 Ti' 96 Ti' Ti' Ti' Ti' 1 2 4 425 309 .87 1 3 4 19 47 Ti' 20 20 5 Ti' 9 12 5 Ti' Tr 33 454 310 8.62 31 1 28 28 Ti' 89 3 3 Ti' Tr 7 8 445 311 26.25 49 5 10 32 Ti' 97 Ti' 1 2 Ti' Ti' Ti' 1 330 312 .32 3 Ti' 12 43 7 25 1 1 9 13 44 2 6 74 299 314 .22 10 Ti' 12 10 24 57 2 1 3 Ti' 5 3 24 1 6 40 298 315 .31 3 Ti' 2 1 9 15 Ti' Ti' Ti' 7 Ti' 8 60 6 Ti' 2 85 355 APPENDIX III (continued) Sample % Deti'itala Authigeni BiogeicC Grains No. Sand p H M Rx V Y Total G otal P B D R F Po 0TotalCounted

316 9, 13 44 3 19 29 3 1 99 Tr Tr Ti' Tr Tr 442 317 16,27 48 S 38 1 2 99 Ti' Tr 302 318 1,21 54 8 5 24 Ti' 1 92 6 Ti' Ti' Tr 7 480 319 8. 15 21 3 31 29 Tr 85 Ti' Ti' 1 Ti' 13 14 350 320 57.98 51 8 2 35 1 98 Ti' Ti' 1 1 279 321 .22 26 4 21 14 Ti' 64 25 2 8 Tr Tr 36 307 326 .89 13 3 32 12 1 Ti' 61 21 2 1 S 8 Ti' Tr 39 393 327 18.20 60 6 5 27 Tr Tr 99 Ti' Ti' Ti' Tr Ti' 373 328 .92 15 3 45 18 Ti' 81 Ti' Ti' 2 Tr Ti' 5 10 Ti' 19 318 329 18,90 58 6 11 25 Ti' Ti' 100 Ti' Ti' 358 330 66.64 59 9 3 28 Ti' 100 Tr Ti' 367 332 3.31 40 3 9 23 2 77 Ti' Ti' 3 18 Ti' Ti' 23 328 333 73.95 46 9 3 39 2 Ti' 100 Ti' Ti' 319 334 2.43 22 Ti' 8 14 2 46 2 Ti' 3 45 3 Ti' 54 430 335 .60 34 3 14 22 Tr Tr 73 4 Ti' 2 12 8 Ti' Tr 27 344 336 32.38 55 4 4 37 Ti' Tr 100 433 337 .42 11 Ti' 31 7 50 1 1 16 5 Ti' 7 16 2 3 49 336 339 13.42 41 2 27 27 Ti' Ti' 98 Ti' Ti' Tr Tr Ti' Ti' 1 379 340 72.85 56 9 4 30 Ti' Ti' 99 Ti' Ti' Ti' Ti' 363 341 13.64 41 2 24 29 Ti' 96 4 4 324 342 42,28 52 5 15 24 1 Ti' 98 1 1 Ti' Ti' 370 343 2,13 50 4 9 31 Tr 94 Ti' Ti' 6 6 304 344 14,17 35 2 17 32 1 Ti' 86 4 Ti' 4 Ti' 2 8 10 484 345 7,33 34 4 11 37 4 Ti' 90 4 4 Tr Ti' 1 3 6 333 346 .35 5 7 1 1 16 Ti' Ti' 8 1 13 44 12 1 3 84 419 347 4.82 25 20 25 1 71 3 3 1 5 20 27 348 17.43 43 1 13 38 Ti' Ti' 96 1 1 Ti' Ti' Ti' 2 3 409 349 69.58 55 9 2 31 1 Ti' 99 Ti' Ti' 1 384 350 .40 14 3 7 10 Ti' 34 Ti' 2 3 7 1 25 13 15 2 Ti' 63 374 351 8.83 30 2 26 24 1 82 Ti' Ti' 1 16 Tr 17 336 352 40.26 52 2 11 32 Ti' 97 3 3 323 00 APPENDIX III (continued) Sample % Detritala Authigeni Biogenj& Grains No. Sand p H M Rx V Y Total C PyTotal P B D R F Po 0TotalCounted

354 51.55 55 4 5 35 Tr Tr 99 1 1 Tr Tr 438 355 83.34 60 7 2 30 Tr 99 1 Tr 1 382 356 .40 6 Tr 3 1 16 Tr Tr 4 Tr 10 61 5 Tr 3 83 427 357 13 4 16 2 23 Tr Tr 1 3 55 16 1 1 77 297 358 .22 19 1 20 9 Tr 50 Tr Tr 4 Tr Tr 20 21 3 49 367 359 40.42 58 3 13 24 1 100 Tr Tr 392 360 82.23 59 6 2 33 Tr 100 330 361 .13 8 37 6 50 Tr Tr 6 42 2 49 429 362 .05 3 67 1 70 Tr 27 2 30 439 363 2.55 15 Tr 55 6 1 Tr 78 Tr 22 22 312 364 .64 1 76 Tr 78 Tr 22 22 339 365 9.78 43 2 48 Tr 92 7 7 327 366 31.98 60 3 14 20 2 Tr 99 Tr Tr Tr 406 371 11.09 Tr Tr 6 5 71 83 Tr Tr 16 Tr 17 367 372 33.52 2 Tr 4 5 67 78 Tr 22 Tr 22 410 374 15.93 15 1 6 15 63 100 Tr Tr Tr Tr 384 375 83.96 54 7 2 35 2 Tr 100 Tr Tr 460 376 2.33 6 Tr 5 5 71 87 Tr Tr Tr 2 8 2 12 406 377 11.16 2 Tr 5 5 87 99 Tr Tr 1 382 378 45,87 14 3 5 13 65 Tr 99 Tr Tr Tr Tr 384 379 89.28 55 9 Tr 30 4 Tr 100 Tr Ti' 330 380 83.47 65 6 3 26 Ti' 100 Ti' Ti' 340 381 4.73 40 2 34 18 94 Ti' Ti' Ti' 4 2 6 407 382 37.82 51 2 21 24 Ti' 99 Ti' Ti' Ti' 230 383 73.79 57 5 14 23 Ti' 99 Ti' Ti' Tr Ti' 451 384 48.54 56 3 19 22 Ti' Tr 100 513 385 4.31 34 Ti' 46 14 Tr 95 Ti' Ti' 4 Tr 5 507 386 45.43 59 5 9 24 Ti' 100 386 387 .44 26 2 25 9 Ti' 62 1 1 4 2 5 13 11 Ti' Tr 36 335 393 ,50 15 2 21 18 Tr 56 Ti' Tr 3 Ti' 4 16 20 Ti' 1 44 307 N.) 394 14,74 30 3 23 39 2 Ti' 96 1 1 Tr Ti' 1 Ti' 3 405 APPENDIX III (continued) Sample % Detrital a Authigeni° BiogeninC Grains No. Sand 0 H M Rx V Y Total G Ps' Total P B D R F Po 0TotalCounted 395 63.25 51 5 6 37 Tr Tr 99 Tr Tr Tr Tr Tr Tr 527 396 .80 29 Tr 15 22 66 4 Tr 2 21 7 Tr Tr 34 408 397 31.04 41 1 13 37 Tr Tr 94 Tr Tr Tr 5 5 372 398 50.58 43 2 16 35 2 Tr 99 Tr Tr 1 1 330 399 57.22 52 4 7 46 Tr Tr 100 Tr Tr 452 401 .11 2 15 Tr 18 Tr Tr Tr 3 Tr 5 46 11 2 16 82 883 404 60.99 42 4 5 49 Tr 100 Tr Tr 328 405 .69 14 9 13 36 6 3 6 34 13 3 Tr 64 284 406 6.64 SO 3 25 17 Tr Tr 98 Tr Tr 1 1 327 407 85.29 51 8 1 37 Tr 98 2 2 Tr Tr Tr 339 408 92.11 36 8 3 53 Tr 100 308 409 .70 Tr Tr Tr 9 78 7 1 4 99 281 409a .41 Tr Tr 1 5 83 7 Tr 3 99 333 410 1.02 21 1 50 21 Tr 92 Tr Tr Tr 6 Tr 7 293 411 23.28 47 2 10 41 Tr 100 Tr Tr 312 412 1.10 36 Tr 20 18 76 7 2 12 3 1 24 331 413 .24 24 2 25 12 Tr 64 Tr Tr 19 Tr 1 14 Tr Tr 36 332 414 51.56 54 2 9 34 Tr Tr 100 Tr Tr 279 415 50.30 59 5 2 35 100 Tr Tr 370 416 1.04 39 4 15 29 2 Tr 89 6 Tr 1 3 Tr 11 578 417 77.64 54 9 1 35 100 Tr Tr 421 419 .72 17 Tr 23 20 4 64 1 1 Tr 5 18 9 1 2 35 283 420 1.36 5 Tr 6 7 64 83 1 1 Tr 2 8 5 Tr Tr 16 299 423 35.52 30 5 5 55 5 100 Tr Tr estimated 424 1.86 15 2 10 11 34 72 1 1 Tr Tr 2 19 3 2 Tr 27 412 425 62.30 28 5 4 30 30 97 Tr Tr Tr 1 Tr 2 221 426 44.33 32 4 5 53 2 96 Tr 4 4 362 427 343 34 4 17 33 Tr Tr 88 Tr Tr 1 Tr Tr Tr 3 7 11 356 428 40.77 34 4 7 48 Tr 94 Tr Tr Tr Tr Tr 4 Tr 6 344 429 7.14 29 3 20 36 88 Tr Tr Tr Tr Tr 3 7 11 456 430 .20 Tr 5 Tr Tr 7 Tr Tr 15 47 20 1 2 92 327 0 APPENDIX III (continued)

Sample o/ Detritala Authigen&' BiogenicC Grains No. Sand p H M Rx V Y Total C Py Total P B D R F P0 0TotalCounted

431 .44 3 3 Tr 2 9 3 Tr 10 68 8 1 91 423 432 .43 4 10 5 3 22 1 1 Tr Tr 6 55 12 Tr 3 77 489 433 64 8 Tr Tr 4 Tr 14 5 Tr 7 69 4 1 86 384 434 .57 Tr 2 Tr 3 3 Tr 9 77 6 Tr Tr 97 367 435 2.36 30 1 6 27 4 68 3 3 Tr 4 18 6 Tr Tr 29 388 436 .75 13 Tr 7 16 2 39 2 2 2 Tr 6 41 7 Tr 4 61 421 437 .43 1 Tr 1 3 Tr 2 25 64 7 98 275 437a .56 4 Tr 2 3 Tr 10 2 1 11 74 2 90 295 438 .79 2 3 2 1 7 2 Tr 8 76 4 Tr 3 93 428 439 1.72 22 4 5 16 1 49 Tr Tr Tr Tr 4 33 10 Tr 2 51 346 443 .34 39 4 3 41 Tr 88 4 4 1 2 3 Tr Tr 9 422 444 10.84 Tr 1 1 Tr 3 Tr 15 71 6 1 4 97 314 445 .62 7 Tr 5 3 1 16 Tr Tr 1 Tr 13 51 13 2 3 83 366 446 66 7 1 10 8 1 29 1 1 19 21 24 2 5 70 301 447 .40 5 Tr 6 3 Tr 15 Tr Tr Tr Tr 39 13 30 3 Tr 85 664 449 .23 2 Tr 6 3 2 13 Tr Tr Tr 1 7 70 8 Tr 86 369 450 .36 5 3 2 5 15 Tr 1 6 68 9 Tr Tr 85 426 451 .38 2 6 1 Tr 10 Tr Tr Tr 9 61 15 1 3 89 410 452 .50 19 12 7 Tr 38 5 40 14 Tr 2 62 330 453 .38 3 Tr 3 1 5 13 Tr Tr 4 Tr 8 63 10 Tr 3 87 446 454 1.71 14 Tr 21 18 12 66 2 2 Tr 4 6 21 Tr Tr 32 463 455 .30 1 6 Tr 5 12 Tr Tr 1 12 25 46 1 2 87 296 456 .52 2 Tr Tr 2 3 8 4 1 10 72 3 Tr Tr 92 288 457 .38 3 7 2 Tr 12 1 1 12 50 11 1 12 87 379 458 .51 Tr 2 2 3 7 Tr Tr 3 62 7 Tr 2 94 340 459 .60 11 1 33 7 Tr 53 Tr Tr 11 11 20 Tr 6 47 386 460 .44 3 41 2 Tr 46 Tr Tr 1 5 35 12 1 Tr 54 378 461 .47 3 3 1 13 20 4 Tr 9 60 6 Tr 1 80 457 462 .32 3 12 4 3 22 Ti' Tr Tr Tr 14 35 18 Ti' 8 77 322 463 .41 Tr 4 2 Tr 7 Tr Tr 33 45 14 Tr 93 388 'J 464 .88 9 Ti' 2 7 Ti' 18 Tr Tr Tr 1 9 66 4 1 82 407 i. APPENDIX III (continued)

Sample 90 Detritala Authigenlc1' Biogeni Grains No. Sand p H M Rx V Y Total G Pv,Total P B D R F Po 0TotalCounted

465 .40 5 1 11 6 3 27 3 3 Tr Tr 11 44 8 Tr 6 70 419 466 .37 2 Tr 2 4 Tr Tr 22 54 11 Tr 8 96 639 467 .59 2 Tr 1 Tr 5 1 Tr 8 76 7 3 96 331 468 1.73 18 2 6 15 1 42 Tr Tr Tr Tr 4 50 2 Tr 59 486 469 .45 2 1 Tr 4 Tr 4 87 4 Tr 96 325 470 1.13 2 2 3 Tr 7 Tr 8 74 3 8 93 453 471 .68 Tr Tr Tr Tr 2 1 Tr 11 71 3 Tr 11 98 500 472 .39 3 4 2 3 12 2 Tr 9 68 7 Tr Tr 88 295 473 .40 2 1 2 2 6 1 1 5 81 4 Tr 1 94 372 474 21.95 5 1 1 90 1 97 1 1 1 1 2 est. 475 84.95 52 6 2 39 Tr Tr 99 Tr Tr Tr Tr Tr Tr 442 a b Detrital minerals Authigeni.c minerals cBiogenicmaterial Q = Light colored minerals (quartz and feldspar) G = Glauconite P = Planktonic foraminifera H = Colored minerals (ferromagnesians) Py = Pyrite B = Benthonic foraminifera M = Mica D = Diatoms Rx = Rock fragments R = Radiolarians V Volcanic glass F = Plant fragments y = Yellow grains Po Pollen 0 = Other (includes Spicules, Echinoid Spines, Shell fragments). Tr= <1% * Hydrotrillite (complex organic iron authigenic mineral) includes pumIce fragments

(.%) u-I 253

APPENDIX 4

METHODS OF SEDIMENT SAMPLING AND ANALYSIS

Core Sampling Methods

Forty cores up to 600 cm in length were taken with a Ewing piston corer modified to take a plastic liner. A Phieger corer, used to trip the piston corer, obtained undisturbed surface sediment cores up to 60 cm in length (Appendix 1). The liner containing the core was removed from the piston corer, cut into ten foot sections, put in galvanized tubing,and stored in a refrigerated cooler at 4°C.Later, to sample and log the core, the plastic liners of the ten foot sections were cut with a circular hand saw.The sediment itself was cut with a violin string while the core was still quite moist and before dessication cracksdeveloped. Immediately after cutting, the cores were photographed in black and white, and color; then they were logged.Lithology, sedimentary structures, biological features, and notable compositional characteristics were described.Four hundred and seventy-five samples 3 cm long were cut from one-half of the original core.The other one-half was archived intact. 254

Coring Anomalies

Vacuum action of the piston as a core is being taken and pulled out of the ocean floor occasionally may cause deformation, false sedimentary structures, and loss of the upper portions of piston cores. As a result, in some Astoria Fan cores, a few thin coarse layers were flipped to vertical orientation, sections were pulled apart, and portions were stretched due to variation in cohesiveness of material. Completely "slurped up" material occurred at the bottom of the cores when the corer had only partial penetration into the sediment; as the piston was drawn up the barrel to pull the corer out of the sea bottom, material was drawn in from only. the stratigraphic level at the bottom of the barrel. Correlation of different cores was affected by anomalies of the coring process and by rapid lateral changes in stratigraphy of fan sediment.About one-half of the Phieger trigger weight and piston core pairs could not be correlated.Either there was a change of the stratigraphic succession in the distance betweenthe two cores, there was a coring anomaly, or there was no lithologic difference to use for correlation.Sometimes,stratigraphic difference between the two cores resulted from loss of olive gray clay at the top of the piston core.Usually. this was true when there was evidence for much sucking in the core.Possibly, because of the great 255 vacuum when pulling the sediment into the corer, the less cohesive material at the top of the piston core was homogenized with water and lost before storage.Another explanation for loss of upper core material may be that the beginning penetration of the barrel occurred with the piston fixed at the bottom of the barrel.This would prevent the surface and upper sediment from entering the barrel. Occasionally, two piston cores were taken at the same station and correlation was not possible between the corase layers.Since the ship's drift probably was no more than a mile between stations, it appears that a facies change may have prevented stratigraphic correlation. About one-fourthof the trigger and piston core pairs had a positive correlation using color features and lithologic changes such as ash layers.Another one-fourth of the pairs of trigger and piston cores had a probable correlation.

Methods of Analysis

Size Analysis

Size analyses were done for 350 samples.First, the coarse fraction (> 62i) was removed by wet-sieving and the fine fraction was collected in a one liter cylinder.Then the hydrometer method, ASTM designation: D422-54T, 1954, was used for size analysis of fine fraction because results of hydrometer and pipette methods on experimental samples were comparative (Sternberg and Creager,

1961).The ASTM method was modified slightly so that the total weight of the fine size fraction was determined by taking an initial hydrometer reading or a pipette split of the total sample of fines; then total sample weight was obtained by adding weights of fine and coarse size fraction.The size classes of the coarse fraction were 4 determined by sieving on three inch'VTstandard sieves or by using the Emery sedimentation tube, as modified by Poole (1957). Statistical parameters of Trask (1932), Inman (1952), and Folk and Ward (1957) were calculated by the IBM 1420 computer.In addition, percentages of sand,. silt, clay, and mud (silt and clay), and ratios of silt:clay, sand:clay, and sand:mud were determined. From these data, X-Y plots of mean versus sorting,, mean versus skewness, and sorting versus skewness were made by the IBM 1620 computer coupled with the X-Y plotter.With the same computer equipment, sand:silt:clay percentages were plotted on the triangular diagram of Shepard (1954), and the silt:clay ratio was plotted versus the water depth. All the samples were used for plots of Inman statistical parameters, even though the sediment samples of clay, size had open ended curves without measured data. points in the finest sizes.To obtain the size statistics for the clay size samples, the computer 257 extrapolated from a straight line interpolation of the last two data points.The 48 hour values extrapolated by the computer were within the accuracy of the 48 hour hydrometer reading.Using this com puter extrapolation method, sample curves terminated naturally before 14 size.Since Stokes law has been found to hold to colloidal size (1/10, 000 mm or i3-l44) (Krumbein and Pettijohn, 1938), the extrapolated computer values were not of a smaller size than would settle according to Stokes law.

It appears that the method of extrapolation used in this study is more valid than the artificial termination of all cumulative size

curves at 14c (Folk and Ward, 1957) or 10 (Van Andel, 1964) that previous investigators have used.With Folk and Ward's or Van Andel's methods, slopes of cumulative size curves are artificially changed so that the 100 percent termination of the curve occurs at 14 or 10 j.As a result, statistical parameters from artificial termination may be different than values from original empirical data.In the author's method, the slope of the natural curve is ex tended to obtain extrapolated data points and statistics. Inman statistics are used for two reasons.These statistics give a better estimate of the moment measures of the sample than do the Trask (1952) statistics; extrapolation for the Inman (1952) statistics is necessary only to the 84th percentile, rather than the

95th percentile which is required by Folk and Ward (1957). Coarse Fraction Analysis

General.The same samples that were analyzed for texture were also analyzed for coarse fraction composition (Appendix 3). After the coarse fraction was wet-sieved from a sediment sample, a wet split of the coarse fraction was taken with a reagent pipette and spread over a micropaleontology slide.This method was more accurate than dry splitting because static electricity attracts diatoms to the sheet metal of the dry splitters. A binocular microscope was used in counting 300 or more constituents on each slide.Con- stituents were classified into the following groups and number percentage for each group was calculated. Quartz-feldspar Group.It includes light colored, pure mineral crystals of quartz, feldspar, and possibly some carbonate minerals. Acid digestion indicates that the amount of carbonate generally is low (Appendix 6).Yellow, weathered quartz-feldspar grains are counted separately. Ferromagnesian Group.It contains colored, pure mineral crystals of ferromagnesian minerals.Those of questionable identification are counted as rock fragments. Mica.All types of mica, including biotite, muscovite, phlogo- pite, plus other closely related platy minerals, such as chlorite and talc, constitute this group. Z59

Rock Fragments.This group includes all aggregates of minerals in which any one mineral crystal makes up less than 50 percent of the grain. Any grains of indefinite identification are included, but these comprise only a small part of the rock fragments group.Generally, rock fragments are chips of volcanic rocks, mainly basalts and andesites. Volcanic Glass.\Titr.ic ash, glass shards, and pumice fragments are all included in these counts.The pumice is mainly, found in core D-10 samples.The glass grains are readily distinguishable with a binocular microscope. Glauconite.Only. typical botryoidal, fissured, and rounded glauconite grains have been counted, and these are only rarely encountered. Pyrite.The pyrite typically is in reniform, botryoldal shapes and is tarnished.Nearly, all the pyrite appears to be. authigenic and probably is formed during reduction of organic material. Very often the tests of foraminifera contain pyrite. Planktonic Foraminifera.The planktonic foraminifera are mainly Globigerina pachyderma, 0. bulloides, 0. quinqueloba, 0. eggeri, Globigerinita uvula, Globorotalia scitula, and Orbulina universa.Globigerina pachyderma and 0. bulloides.T h e planktonic fórami.nifera are readily distinguishable; only fragrnnts over one-half of normal size have been counted. Benthic Foraminifera.In the total coarse fraction only small quantities of total deep-.sea benthic foraminifera and displaced shallow water benthic foraminifera are encountered.Flotation separation of foraminifera for study of displaced benthic fauna shows that a variety of forms are present in the sediments (Appendix 9). Diatoms.The most common and best preserved diatoms are the centric forms, particularly the Coscinodiscoid type.Each disk has been counted as one diatom.Occasionally, species of Bidduiphia of Rhizosolenia, and Chaetoceros are observed. Radiolarians. A wide variety of unidentified types is present and the preservation is quite good.Radiolarians are readily distinguishable from the diatoms. Plant Fragments.This category includes all fibrous and cellu- lose types of organic material.Algal type fragments are most common, but wood fragments occasionally are numerous. Pollen Grains.Primarily coniferous types of pollen, such as pine, cedar, hemlock, fir, and spruce are found.Because of the size selection at 62 smaller non-coniferous types are rare in the coarse fraction. Other Biogenous Remains.This group contains spicules, macroscopic shell fragments, echinoid spines and fecal pellets.All of these constituents are rare except for the spicules.Spicules 261

sometimes become very numerous when assemblages of bathysiphon tests are in the sediment.In these samples the anomalously high spicule counts have been disregarded because bathysiphons selectively pick sponge spicules for their tests and because distribution of bathysiphon tests is patchy.

Mineralogy

The refractive index was determined by oils for 30 samples that contained a significant quantity of ash (Appendix 8).These oils were calibrated to.002increments of refractive index.Heavy mineral separations were made using a centrifuge (Fessenden, 1959) with tetrabromethane (sp. gr. = 2.96)as a heavy liquid.Twenty representative layers were analyzed for heavy and light minerals

(Appendices6and 7).Light mineral analyses were completed by using a modified form of Bailey. and Stevenst(1960)method of staining feldspars,. by making coarse fraction counts, and by determining carbonate with acid digestion.Heavy and light mineral percentages were estimated by counting more than64or 100 grains respectively

(Dennison and Shea,1966). The light mineral groups have been described mainly in the discussion of coarse fraction divisions or are rnonomineralic.The heavy mineral groups include the following mineral species: Rock Fragments and Weathered Grains.Generally, rock 262 fragments are the dominant constituent of this group.The weathered grains often are highly stained with limonite and hematite. Many of the rock fragments contain magnetite crystals which probably cause their separation with the heavyminerals. Opaque Minerals.Magnetite, combined with variable 'amounts of illmenite, is usually the most abundant opaque mineral. As an alteration product, leucoxeneis quite common and occasionally is as abundant as magnetite.Hematite and limonite often occur as an alteration of other minerals and sometimes are nearly as common as magnetite.In layers with a very low sand content (Appendix 7, samples 27, 371 and 80) authigenic pyrite is occasionally the most abundant opaque mineral. Igneous Amphiboles. Common brown and green hornblendeis most important in this group, but usually basaltic hornblendeis present in small amounts. Metamorphic Amphiboles.Blue-green hornblende makes up nearly the entire amount in this category. Orthopyroxenes.Hypersthene makes up nearly all the grains in this group.Typicaily. the grains contain a high number of magnetite inclusions and occasionally the grains have borders with a coxcomb shape or glass rims.Enstatite possibly is present in some samples. Clinopyroxenes. Augite is the most important clinopyroxene, 263 and diopside appears to be present in most samples in small amounts. Titan-augite usually is found, but in very small amounts. Garnet.Pink and colorless varieties of garnet are present. Epidote.In the epidote group epidote is most common, but zoisite and clinozoisite usually are present in small amounts. Zircon and Apatite.Both zircon and apatite occur in small and nearly equal amounts. Andalusite.The analusite group includes kyanite as the most common constittent, but silimanite may be present occasionally. Micaceous Group.Biotite and chlorite are the most important micaceous minerals and are present in all samples; muscovite usually is found but is not as common as the other minerals. Other Minerals.Other minerals that occasionally are present include sphene, rutile, tourmaline, monazite, and some of the zeolites.

Analysis of Benthic Foraminifera

Total benthic foraminifera were counted in the coarse fraction analyses.Qualitative lists of species of displaced benthic foraminifera were made for 25 representative samples from coarse layers, clayey- silt layers, and clay layers.The samples that were analyzed for the faunas were washed carefully, screened at the 62 j. size, and then floated with tetrachiorethane to separate the micro fauna from 264 the detrital material.For each of these samples the relative abundance of in situ and displaced benthic foraminifera was estimated. APPENDIX V

CORRFLATIONOF STRATIGRAPHY IN PISTON AND PHLEGER CORES(ALL DATA IN CM)

Core Nuni- Brown- PC-PH Olive to Radio Foram Ash Remarks ber P.C. a/ OUve/ Correl. c/ Gray J*

A-i 519 NP No Basis 105 95 105 92 claywith 15% ash

A-2 620 NP No Basis 170 No 200 150 90-160 cm stretched Data A-3 582 1.,5 40 no 58 50 121 21 ash centered in olive correlation gray

A-4A(C) 475 6 2.75-cor- all olive 400 No 170 top 60 cm stretched relation gray clay Data

B-2 400 NP 29 no cor- 15 No 40 NP top of core deformed relation Data

B-3 262 1 41 no cor- 1 No 15 NP nearly all olive gray clay relation Data lost from piston core. Pheleger entirely olive B-4 609 52 no cor- 0 No 239 22 (in gray clay relation Data Phleger)

B-5** 518 NP 32. 5 no all olive 238 No 50 anomalous core** correlation gray clay Data

B-6 356 4. 5 44. 5 no 50 No 55 NP 140-200 pulled correlation Data 220-280/apart

C-2 560 NP No Basis 145 90 239 80 N) 0' Continued on next page Ui APPENDIX V

CONTINUFD Core Num- Brown- PC-PH Olive to Radio Foram Ash Remarks ber P.C. a! Olivek/ Correl. LI Grayd/* f/*

C-3** 470 NP correla- allolive 420? No 97 325-425 cm stretched tion? gray clay Data

K-2 600 2 correlation 100 No 125 50 Data

C-4 600 4 40 50 No 145 NP 15-50 cm stretched Data

C-4 2 585 3 30 corre- 15 No 78 NP lation? Data

6509-9A 230 4. 5 correlation 100 No 98 NP top 30 cm stretched Data

D-10(c) 214 NP 25 corre- all olive 160 No 165 core pulled apart lation gray clay Data 180-205 cm

D-2 405 NP 53 no 16 No No NP Phieger all olive gray correlation Data Data clay

D-3 600 0.5 3Ono 90 90 120 12-15 correlation

D-4 582 1 26 no 40 2 112 10 correlation Continued on next page APPENDIX V CONTINUED Core Num- Brown- PC-PH Olive to Radio Foram Ash Remarks ber P. C. / Ol4ve J Correl. LI Gray d/* LI

K-i 530 correlation 210 180 210 70

6509-8 0 2 No Basis No No No NP No piston core Data Data Data

6509-7 270 3 correlation 100 111 120 NP 2% ash 35-50 cm

6509-6A 300 1 No Basis 100 140 No NP 1% ash 0-85 cm; Data 0% below

6509-16 270 4 correlation 90 101 142 NP

E-2 600 NP 10 correla- 79 70 No 70 No biogenous material tion Data after 70 cm

E-7 42 NP 41 no corre- -. all olive 45 No 10 lation gray clay Data

E-3 540 NP 47 no corre- 80 32 85 50 20-50 stretched lation

6509-5 (C) 148 NP correlatioii? all olive 116 No 125 gray clay Data

E-4 0 1 No Data No Data No No No no piston core Data Data Data t'J Continued, on next page APPENDIX V

CONTINUED Core Num- Brown- PC-PH Olive to Radio Foram Ash Remarks ber P. C. a/ Olive b/ Correl. LI Gray /*

6509-4 (C) 504 0.5 correlatioii? all olive 430 No 170 Piston core stretched 20 gray clay Data cm at top

6509-3 (C) 252 correlation ll olive 199 No 125 gray clay Data

F-2 540 NP No Basis 70 15 83 NP 3% ash at 15 cm

F-3 (C) 50 NP 44 no all olive 27 No 40 correlation gray clay Data

F-4 257 NP 36..5 no 0 No 4 NP Phieger all olive gray;0.g. correlation Data missing from piston core

6509-1 (C) 275 NP 8 all olive 157 No NP correlation gray clay Data

6509-2 (C) 360 NP No Basis all olive 235 No NP grayclay Data

C-i 396 NP No Basis 100-150 101 254 58 30 cm stretched

Footnotes continued on next page Appendix V footnotes

a Length of piston core b.Depth in Phieger core of color change from brown to olive gray clay c Correlation of piston and Phieger core; (20) = number of cm positive adjustment in piston core d.Depth of change from olive gray to gray silty clay in piston core e.Deepest sample with a dominance of radiolariam. f. Shallowest sample with a dominance of Foraminifera g.Deepest ash layer NP Not Present (C) Channel Core * Depth in piston core without correction for stretching and Phieger core correlation ** Anomalous core with repetitive bedding c1* Top of Pbleger core missing APPENDIX VI

LIGHT MINERAL ANALYSIS OF SFLECTFD SAMPLES (PERCENTAGE BY NUMBER)

sub Total Sample Flag K and tot griü2 9 No. SaaI Malaix** Carb.** Qtz. K-Felds Plag An_B* K-RxCa-Rx Ca-Rx Rx count Felds Felds+Rx

Up,er Fan 112 9.2 77 5.2 44. 1 20.3 16.9 ol* 5.1 8,5 5. 1 19 159 1.62 0.79 191 56. 7 39 4.2 36.3 15. 1 17. 8 2,7 8.9 19. 2 31 146 1.09 0. 56 196 84. 9 13 4.6 32. 5 8. 5 4.0 17.0 11.0 27.0 55 200 2. 54 0. 49 202 77.4 44 5.2 26.6 11.6 4.3 ol 8.2 11.6 37,7 58 207 1.69 0.31 205 50. 4 40 5. 9 15. 5 10,0 6. 5 ol 2.5 7.0 58. 5 68 200 0. 94 0. 19 212 77. 4 17 5. 2- 28. 5 7.0 12. 5 and, ol 9.0 15.0 27. S 52 200 1. 45 0. 40 428 40.8 28 6.0 24.6 14.9 17.7 alb,ol 4.6 2.3 36.0 43 175 0.76 0.38 Middle Fan 28 24.. 3 15 27.0 13. 0 24.0 al,ol 6.0 12.0 18.0 36 100 0. 73 0. 37 32 453 8 7.1 32.0 9.3 30.0 1,3 15.3 11.3 28 150 0.82 0.48 62 54.7 6 6.6 34.8 12.9 19.7 2.7 19.7 10.2 33 264 1.1 0.53

267 683 10 4. 5 26.0 10.0 16. 5 ol, and 1.5 8.0 38.0 48 200 0.96 0. 40

270 93,8 5 2.5 29.4 17.5 15.6 lab,ol 2.5 1.9 33.1 38 160 0.88 0.41.

379 98.3 1 2.8 28.6 14.9 14,3 4.6 29 34.9 42 175 1..O 0.41

Lower Fan -

73 15. 2 18 36.-0 18 0 25.0 0 9.0 13.0 22 101 0. 84 0. 55 76 9.6 23 46.7 11,7 16..8 aud,ol 1.5 7.3 16.1 25 137 162 0. 87 aib,- lab Continuedon next page 0 APPENDIX VI

CONTINUED sub Tothi Sample Plag K and tot grainQtz Qtz No. Sand Matrix** Carb.** Qtz. K-Felds Plag An-B K-RxCa-Rx Ca-Rx Rx countFelds Felds+Rx

77 74.8 5 6.0 31,4 9.8 26.8 4.6 22.9 4.6 32 153 0.84 0.45 224 67. 8 5 33. 1 11. 4 25. 9 aib, lab 1. 8 0. 6 27. 1 30 166 0. 89 0. 49 330 66.6 7 6.5 31. 4 12.2 14. 5 and, ol 3.4 8.7 30. 2 42 172 1. 15 0. 45 345 7. 3 61 9. 9 33. 3 13. 1 16. 7 4.2 13. 7 9.0 37 168 1. 10 0. 49

352 40. 3 13 5. 7 24. 0 18.0 18. 0 ol, and 3.0 9. 6 27. .5 40 167 0. 67 0. 32 355 83. 3 6 3. 1 30. 2 18. 1 18. 8 3. 3 4.0 26. 2 34 149 0. 81 0. 42 395 63.2 14 4.0 27.8 14..4 13.3 6.1 6.1 32.2 44 180 1.0 0.39

* al = albite,ol = oligoclase, and = andesine, lab = labroadorite ** Matrix defined by Williams, Gilbert, Turner (1958) <20i,andcarb = carbonate % by weighty and the other constituents are % by number; Qtz = quartz,K-felds = potassium feldspar, Plag = plagioclase, Plag. An-By. = variety of plagioclase found, K-Rx = potassium rich rock rock fragments, Ca-Rx = calcium rich rock fragments, Tot. Rx = total rock fragment %,Qifeldsquartu feldsparatio, 9/fel + Rxquartz: feldspar + rocks.

I- APPENDIX VII

HEAVY MINERAL ANALYSIS OF SELECTED SAMPLES (PERCENTAGE BY NUMBER)

V. V. 0. 4) U v 0

bO C) 4)

I - . 8 L 4)00)4) ,-i ( p.. oo (I Z v XOX oQ 0 . 0 0 E0 Upper Fan 191 56.7 8 35.3 12.3 233 17.8 4.111.0 17.82.8 2.8 1.41.4 2.8 2.8 73 193 52.0 5 3.1 21.1 73 20.2 4.611.0 18.42.8 1.8 3.60.9 7.3 0.9 109 196 85.0 7 5.5 11.3 17.5 16.3 3. 821.3 21.3 1.3 2.6 1.3 1. 3 1. 3 2.6 80 198 41.9 6 4.8 21.6 5.2 19.8 4.312.1 21.63.4 1.8 1.80.9 5.2 2.6 116 202 52.1 3 4.0 21.1 16.7 13.3 4414.4 16.72.2 2.2 442.2 2.2 90 205 50.4 4 1.5 25.3 8.4 19.3 7.2 6.0 19.3 1.2 1.2 1.21.2 7.2 2.4 83 207 47.8 3 3.0 36.5 0. 8 13. 5 5. 4 6.8 16.2 1. 4 1. 4 2.7 1. 4 1. 4 2.7 74 212 77.4 7 3.8 30.1 22.9 8.4 3.6 4.8 16.8 1.2 2.4 3.6 6.0 83 Mdd1e Fan 27 0. 3 2 13.2 11.0 6.0 3.0 1.0 1.0 1.0 77. 0 64 28 24.3 5 3.0 24.0 22.0 10.0 6.0 26.0 2.0 2.0 8.0 100 31 0.1 1 24.1 1.4 1.4 1.4 1.4 94.4 71 32 45.3 16 5.2 23.4 11.7 11.7 1.3 1.3 39.0 1.3 3.91.3 1.3 3.9 77 62 54.7 10 9.0 21.2 14.1 13.0 13.0 13.0 4.7 5.9 3.5 5.9 5.9 85 65 23.9 10 5.2 33.8 16.9 12.3 1. 5 4 6 20.0 1. 5 1. 5 6.2 3. 1 65 Lower Fan 72 1.3 2 3.9 2.0 2.0 4.0 1.0 91.0 100 73 15.2 7 4.5 29.7 12.2 9.5 1.4 54 24.3 4.1 13.5 4.1 74 76 9.6 0.826.4 9.7 15.3 2.8 5.619.4 2.8 1.416.7 72 77 74.8 10 8.1 18.1 13.9 18.1 2 8 5.6 29.2 1.4 1.4 2.8 2.8 4.2 72 80 1.4 7 14.9 54 48.6 45.9 74 82 0.7 9 15. 8 10. 8 44.6 44.6 65 N) N APPENDIX VIII CHARACTERISTICS OF ASH-RICH LAYERS

Inman Core (cm) °A % Refractive Type of Core# Sample# Depth* Thkkness Sand Silt Clay Mean Sorting Glass Index Layer**** Interchannel Upper Fan C-2 54 84 14 0.3 75.923.8 7. 4 1.6 95 1. 504-1. 508 V A-2 86 50 3 15.5 56.7 27. 8 7.0 2. 9 55 1. 504-1. 509 TI A-2 88 100* 2 lf9 71.726.5 7.4 1.9 82 1.500-1.510 V E-3 105 50 1 1. 504-1. 509 - E-2 155 76 3 2.8 38.4 58. 8 8. 4 2 2 38 1. 504-1. 509 TI D-3 166 60 3 1. 504-1. 509 TI G-1 277 58 5 >90 1.504-1. 509 V E-7 424 51 3 1.9 32.265.9 8.9 2.2 34 1. 504-1. 508 TI Middle Fan K-i 4 54 5 6.9 64.428.7 6. 8 2. 6 88 1. 504-1. 508 V K-i 7 70 5 15. 1 71. 8 13. 2 5.8 1. 7 81 1.504-1. 508 V K-2 61 50 3 1.5 76.6 21. 9 7.0 2 2 72 1.504-1. 508 V A-3-2 92 54 4 1.504-1.508 V A-3-2 93 61 3 1. 504-1. 509 V C-3 267 69 5 1.9 51.847.0 8.2 2.6 69 1. 504- 1. 508 TI C-3 260 97 5 .5 57. 1 42. 4 8. 2 2. 3 68 1. 504-1. 508 TI 290 233* 3 3.1 48.848.1 8.0 26 53 1.500-1.510 TI B-S 292 337*** 1 11.4 49.938.7 7.5 3.4 65 1.504-1.508 TI B-5 294 429*** 4 16.1 51.532.4 6.9 3.4 53 1.504-1. 508 TI

hapnel Upper Fan D-iO 197 113 23 8. 8 30. 5 60. 4 8. 8 2 4 18 1. 504-1. 508 D-I0 203 148 35 67.6 13.7 18.8 4.0 4. 6 20 1. 504-1. 509 D-10 205 154'L 25 50.4 25,923,7 5,8 3.3 53 1.504-1.509 TI -J f (J Continued on next page APPENDIX VIII

CONTINUED

Core (cm) Ininan Refractive Type of Core# Sample II Depth** Thickness Sand Silt Clay Mean Sorting Glass Index Layer****

D-iO 207 l7OJ \25 47.8 31.021.4 5.7 34 53 1.504-1. 509 TI F-3 420 87 10 1. 4 34. 1 64. 5 8. 8 2. 2 64 1. 504-1. 508 Tf Middle Fan 6905-5 374 96 _--12 15.9 64.2 19.9 6.4 2.4 63 1.504-1.509 TI 6509-5 375 104J 83.9 11.7 4.4 3.3 68 2.2 1.504-1. 509 TI 6509-5 377 116 -20 11.2 33.364.3 8.6 2. 26 71 1. 500-1. 510 TI 6509-5 378 120 r 45 9 46 8 7 4 4.2 1 1 65 1 504-1 509 Tf 6509-5 379 125 J 89.3 8.2 2.6 3.0 6 4 1.504-1.509 Lower Fan A-4A 297 149 -26 1.6 65.6 32.9 8.0 2.5 53 1. 500-1. 510 TI A-4A 298 170J 32.7 55.0 12.3 53 1. 4 60 1.504-1. 509 TI 6309-4 369 158 23 50.0 65 1.504-1. 509 - 6509-4 371 170 -1,..- -26 11. 1 64.3 24.6 6. 2 7 71 1. 504-1.509 TI 6509-4 372 196J 33.553.1 13.3 5.2 1.9 67 1.504-1.509 TI 6509-3 391 126 15 1.504-1.509 -

*Core probably stretched ** Depth in core of bQttom of ash-rich layer (Depth corrected for Phieger to piston core correlation) *** Repetitive bedding in core **** V = Vitric ash T'tuffaceous coarse layer } = same layer LZ

costata hispido perigrina J. C) B

perigrina Jvigerina C)

eckisi uggunda

pseudobeyrichi ,oxoatomum

soldanli ;yroidiva C) ariculata lobobuiimina smithi

pacifica pisnine11a a a o o mechani ibicides

delicata califomica assidulina

exitis luliminella . . .

mexicana Iuiimina

suliureceis subadvena I. .spiasa P

seminuda I. argentea olivina fl

juncea Jvigerina o o

angulcea ritaria

miocenica . labradorica . basipInata obioneUa 0 btadyana pstomineila limbata Caidulina z 276

APPENDIX X GRADING CHARACTERISTICS OF COARSE LAYERS--THICK SAND LAYERS

- Depti Weight or Number Percent of >62 ii Fraction Sam- in Ma- Plant Core pie Core tix frag-Fe- Sort- No, No (cm) % Md4 Sand Silt Clay Mica menuMg 1pg( PpperFan F-3 423 44 7 -2 91 6 4 5 0 5 4.5 F-3 474 50 6 -2 93 4 3 1 0 1 1.9

D-10 193 90 40 4 52 23 25 2 1 5 3. 3 D-1O 195 100 35 3 62 17 21 5 17 4 3.3 D-10 196 110 13 3 85 5 10 1 0 7 0.7

D-10 198 119 6 42 24 34 1 1 6 3.8 D-10 199 122 11 3 87 6 7 2 2 8 0.6 D-10 200 125 36 3 64 14 22 2 14 2 4.0 Middle Fan C-3 266 270 81 8 1 53 46 33 Ii 2 3.0 -3 267 274 10 4 69 27 4 5 7 0.7 C-3 268 285 5 3 89 9 2 2 0 6 0.5 C-3 269 298 3 3 96 3 1 1 0 8 0.4 C-3 270 310 5 3 94 4 2 0 0 15 0.5

D-3 119 403 77 7 1 60 40 64 8 3 2.6 D-3 120 408 22 5 18 69 13 5 0. 5 8 1.6 D-3 121 412 9 4 50 47 3 6 0 14 0.7

D-3 123 470 79 7 1 60 39 60 6 2 2.6 D-3 124 473 15 5 7 73 10 15 0 4 1.3 D-3 125 476 89 4 56 40 4 4 0.4 12 0.7 6509-5377* 116 55 6 12 59 29 5 1 1 2.8* 6509-5378* 124 iS 4 46 47 7 5 1 3 1. 1 6509-5379* 130 5 3 89 8 3 1 0 9 0.6 Lower Fan 6509-3397 223 20 5 31 61 8 14 5 2 1.1 6509-3398 234 10 3 51 44 5 16 .9 2 0.8 6509-3399 245 10 4 57 38 5 7 0 4 0.7 6509-4351 433 60 6 9 58 33 26 16 2 3.1 6509-4352 438 13 4 41 54 5 11 3 2 1.1 6509-4354 453 7 4 52 45 3 5 0 4 0 4 6509-4355 465 82 3 84 15 1 2 0 2 0.9

*377 has 87% volcanic glass; 378 has 65%; 379 has 4%.

Continued on next page 277

APPENDIX X Cont. GRADING CHARACTERISTICS OF COARSE LAYERS--AVERAGE SAND LAYERS Depth Weight or Number Percent of>62i Fraction Sam- in Ma- PlUt Core pie Core trix frag- Fe-Soi't- No. No. (cni % Md Sand Silt ClayMica ments Mg thg Upper'Fan B-2 181 45 8 1 49 50 48 6 0 2. 3 B-2 182 50 6 1 63 36 69 8 1 2.5

D-10 212 207 17 3 77 11 12 2 0 7 2.3 Middle Fan K-i ii 150 78 7 1 57 42 14 59 1 2.6 K-i 12 153 9 4 23 74 3 0 1 9 0.7

B-3 134 65 86 7 i 60 40 71 24 2 2.3 B-3 135 68 52 6 1 84 16 88 9 0 1.5

A.-32 97 iii 75 7 1 60 37 15 18 6 3.0 A-32 98 115 18 4 66 24 10 2 3 11 1.2

D-4 147 306 8 1 46 54 75 23 0 2.3 D-4 148 310 5 1 81 18 71 3 1 1.9

C-i 286 369 82 7 2 60 38 64 13 1 2.3 C-i 287 372 19 4 61 32 8 3 1 6 1.2

6509-5374 96 42 5 16 64 20 6 0 1 2. 4 6509-5375 104 9 3 84 12 4 2 1 7 0.7 Lower Fan B-4 43 595 91 8 1 50 50 66 4 0 2.3 B-4 44 599 74 7 1 65 34 20 4 2 2.4

C-4 239 95 5 9 81 10 25 1 3 1.2 C-4 240 103 5 4 69 29 2 3 1 14 0.6

A4a 306 366 iS 4 29 67 4 4 1 6 0.9 A4a 308 383 16 4 50 40 10 5 2 5 1. 1

B-S 319 89 55 6 8 69 23 31 13 3 2.5 B-S 320 93 7 4 58 39 3 2 1 8 0.9

Continued on iiex page 278

APPENDIX X Cont.

GRADING CHARACTERISTICS OF COARSE LAYERS--AVERAGE SAND LAYERS

Deth Weight or Number Percent of> 62/i Fraction Sam- in Ma- Plant Core pie Core trix frag- Fe- Sort- Nc No. (cm) % Md4 Sand S1t Clay Mica menu Mg ing

6509-9329 170 18 5 19 78 4 11 1 6 0.9 6509-9 0 180 6 4 67 30 3 3 9 0.7

6509-4347 398 71 7 5 54 41 20 20 0 3.2 6509-4348 404 23 5 17 74 9 13 2 1 1.1 6509-4349 420 11 4 70 26 4 2 0 9 1.2

6509-6358 113 95 9 1 38 62 20 21 1 2.6 6509-6359 118 15 4 40 55 4 13 1 3 1.5 6509-6360 130 3 3 82 18 1 2 0 6 1.0

6509-16 413 142 25 5 1 96 4 25 14 2 0.8 6509-16 414 147 13 4 52 43 6 9 0 2 0.9 6509-16 415 158 8 4 50 48 2 2 1 5 1.0 APPENDIX XI**

CONTINUED

#of Coarse Beds Total Coarse Layer Thickness(cm) Average Thick.Coarse Beds(cm) Sedimentary Structures

G) 0 ° o Depth in core Depth in core U Depth in core .3 Q 0 bO E E E E E E E ° U C) U ° ° ° C) C) C) 8 8, 0 0- 88 Cores 8888en c' en 't u, rr, o H 8888 8888i c1 en o o H 0 1 CO < 0 < U C) Lower Fan B-6 3 3 49 13 13.0 x 80 47 C-4 3 4 7 29 46 10 12 10.8 x x x ? 67 30 C-4 3 2 1 6 38 4 31 13 2 30 14.9 x x x 27 6509-9 5 2 7 9 23 2 14 7.7 60

6509-7 1 3 3 7 9 20 27 9 7 12 9.3 top 62 55 6509-6 1 7 6 14 3 42 37 3 6 9 6.0 x x x top 70 6509-16 1 4 5 11 68 38 11 17 14.0 x ? x x top 6509-2 0 1 5 6 0 4 64 23 0 4 13 5.7 x x all clay Chaimels Upper Fan *78 D-10 2 5 6 *37 60 18 20 16.0 x x x 78 * 4 43 5 4. 5 x x x all clay 42

F-3 3 3 43 6 6.0 x all clay 53

Continued on next page - SUMMARY OF COARSE APPENDIX XI** LAYER LITHOLOGY # Depth inof Coarse Beds core Total Coarse Layer DepthThickness(cm) in core Average Thick. Depth in core Coarse Beds (cm) o Sedimentary Siuctures '' . UpperInterchannelCores Fan 0 -4 m 'i U) 8tO E 0 8 c 88 8U) t8 H o 888- c' en 8 to8 o ci ci p888881 B-2A-2 1 3 4 '52 10 0 64 25 23 2.04.0 x D-2,E-3 C-2E-2 2.1 21 41 10 18 3 *18 *2 22 41 10 60 54 18 1 21 1 1 1.07.0 x B-3MiddleF-2,F-4 Fan 16no coarse beds; 10 only laminations 26 34 19 31 2 2 2.0 x 2 ii 3 2 12: 58 x E I Continued on next page 0N) APPENDIX XI

CONTINUED

#of Coarse Beds Total Coarse Layer Thickness (cm) Average Thick. Coarse Beds (cm) Sedimentary Structures

Depth in core Depth in core Depth in core o 0 ' C) U U U U U U U U U U U-1 U U U U U U O 0 ' 0 0 0 0 I 0 0 0 0 0 '-4 Lf) Lf) E- ,- en CO >< Cores 0 Et'-:,J m '0E- 0 - Cs) m CO 0 csj 0 Middle Fan 20 6509-5 1 1 2 *12 - 21 10 20 15.0 x all clay 40 Lower Fan 20 A.-4A 1 4 4 3 12 2 *42 33 66 35 2 11 8 22 10.6 x x x all clay

6509-4 0 2 2 3 7 0 *45 35 75 42 0 23 8 25 16.2 x ? x all clay 42 6509-3 1 4 3 8 *4 *44 - 36 4 11 4 9. 7 x x all clay 30 6509.-i 5 11 58 - 51 10 6 7. 8 x x all clay 6 55

* includes mainly ash layers ** coarse layer = 1 cm or thicker *Ic channel? 37 cm of coarse layer lithology 62 cm to core bottom whith occurs in this hundred cm interval

N) OD: APPENDIX XII

SEDIMENTATIONRATES ON ASTORIA FAN (CM! YEARS) Clay Clay Total Rate Rate Depth Depth to thickness thickness Rate post- Rate Pelagic Pelagic to lowest radiolariantoto lowest to first Rate Total glacial Pelagic Clay Clay ash layer Forarniniferaash layer faunal Total post Mt.to Mt. clay post Mt.postglacial Ito Station# (cm) transition (cm)(cm) changcrn)postglacia1 MazaniaMazama postglaciaL MazamaMt. Mazama UpperFan A-i 92 105 9 14 2 4 F-2 - 70 -- 70 6 - 6 -- -- F-4 - 37* -- * 3* -- * D-2 -- 70 -- 70 6 -- - 6 -- -- E-2 78 89 76 89 7 12 2.4 7 12 2,4 c-2 80 145 62 125 12 12 12..0 10 9 i17 B-2* -- 45* 45* 4 -- -- 4 -- -- 100 120 95 115 10 15 3.7 10 14 3.7 50 100 50 100 8 8 9.2 8 8 9.2 1 D-10 170 215* 88 * * 25 -- * 13 -- 51 81* 46 * * 8 -- * 7 -- F-31 86 91* 68 * * 13 -- * 10 -- Middle Fan D-3 60 120 57 117 10 8 7.4 10 9 10.6 B-3* -- 42* -- 28* 4* -- -- 2* -- C-I 58 101 53 91 9 9 8.0 8 18 7.0 A-3 61 100 55 65 8 9 7.2 6 8 1.9 B-S anomelous core ------D-4* 36* 66* 34* 60* 6 5* 56* 5* 5* 4.8* K-i 90 210 81 182 17 14 22.2 15 12 8.7 K-2* 51 100 51 100 18* 8 9.0 8 8 9.0 C3* 97 265* 57* 158* 22* 14 31. 1* 13* 10 16 9* B-4 22* 52* 19* 50* 4 4* 55* * 3* 57* 6509-5 125 148* 95 * * 19 -- * 14 -- Continued on next page APPENDIX XII

CONTINU Clay Clay Total Rate Rate Depth Depth to thickness thickness Rate post- Rate Pelagic Pelagic to lowest radiolarian totcs lowest to first Rate Total glacial Pelagic Clay day ash layer Foraminiferaash layer faunal Total post Mt. to Mt. clay post Mt. postglacial to Station# (cm) transition (cm)(cm) change(cm)postglacial MazaniaMazama postglacial Mazama Mt. Mazama Lower Fan 6509-6A -- 115 -- 112 10 -- -- 9 -- B-6 -- 95 -- 56 8 -- -- 5 -- -- C-4 -- 55* -- 55* 4* .-- * -_ C-4 -- 45* -- 40* 4* -- * _ -- 6509-7 -- 100 -- 91 8 -- -- 8 -- -- 6509-2 -- 235* -- -- * -- * 6509-16 -- 90 -- 90 8 -- -- 8 - -- 6509-9A -- 80 -- 80 7 -- -- 7 -- -- A-4A1 170 400* 130 257* 30* 25 42.6* 20* 20 23.5 650941 190 430 145 275 36 29 48.1 22 19 37.3 6509_31 126 200* 101 * * 19 -- * 15 -- 6509_li -- 157* -- * -- -- * --

* Core did not reach definite trasition to Glacial gray silty clay or coring anomaly caused loss of a portion of postglacial clay. Not calculated in averages if estimate number is present. 1 Channelcores - No ash layer present, therefore no calculation.

t") 03 APPENDIX XIII

SUMMARY OF METHODS OF AGE CALCULATION 10R ASTORIA FAN

Geophysical Data (Shoretal,, 1967)

Fan Apex (Station 5) Lower Fan (Station 12)

Thickness Velocity Layer Thickness YlpcIty 2. 19 km 2 30 km/sec unconsolid. sediments 1. 17km 1.83 km/sec 0. 29 km 6.36 km/sec conolid. sediments 1.33km 5.89km/sec 5.67 km 6. 87 km/sec basalt layer 4.32 km 6. 86 km/sec below 7.94km/sec mantle below 7.91km/sec

Volume of Unconsolidated Sediments 3 a)wedge thickening to one. km at fan apex 7, 500 km 4 2 b)1 km unconsolidated xfan area (2.0 X 10 km ) 3 2 000 km TOTAL 27, 500 ii

Volume of Consolidated Sediments 2.0 X km2X0. 81 km average thickness 16, 200km3 between station 5 and 12 Fan Age Calculate4y Rate of Sedimentation On Fan 1 Unconsolidated sed!ments 1. 675 km average thickness unconsolidated sediments 0 40 rn/jO3 yrs minimum possible fan rate of Pleistocene sedimentatioJ' = 4,018,750 max. est. yrs. for uncon. sed. deposition-" 1. 674 km average thickness unconsolidated sediments 2 1. 7 m/ yrs. max. rate Pleistocene sedimentation for unconsolidated sediments 98S,OOO years observed on Cascadia Abyssal Plain deposition. Considering these as semi-Uthifiedsediments with a compaction loss of 0.25 (Hamilton, 1959) would increase age estimates 1.33 times. r\)

Continued on next page AEPEt'TDIX XIII

CONTINUFD

2 Consolidated sediments 0.81 km average thickness consolidated = 29,000,000 max. years 0. 08 average interglacial, rate X 0. 35 compaction factor for clays to shale (Emery and Bray, 1959)

0. 81 km average thickness consolidated = 940,000 mm. years 1.7 km/103 yrs. max.Pleistocene rate X 0.50 for sand and clay compaction

Fan Age Calculated by Sediment Load of Present Columbia River

1. River Sediment Load (Carlson, 1967) River Sed2eutLo5d (Livinzjton,' 1967;arlson1967) 12, 100, 000 Suspended Sediment 12, 950,000 m3 1,485,000 Bed Load 2, 500,000 m3 Littoral Drift 3, 100,000 m3 13, 585, 000 m /yr Minimum Estimate 18, 550,000 m3/yr Maximum Estimate

2. Unconsolidated 275X104km3 =2,014,000yrs 2.75X104km3 =1,480,000yrs 1. 358 X 10km3/yr with no compaction 1.855 X I0km /yr with no compaction Compaction 25% = 1. 33 times above data (Hamilton, 1959)

3. Consolidated 1.62 X 10 km =3, 440,000 yl's 62 X km 2, 920,000 years 3 1. 358 X 100. 35 compaction km /yr) 1. 855 X 10' (. 35 km /yr compaction)

Chtistmas Flood -- December. 19640.Glenn, 1967)

1.iss x10 km3sediments

MMazama Ash Slump -3 3 00 0. 256xtO km sediments Continued on next page Ui APPENDIX XIII CONTINUE)

Rate Denudation to Columb Ia River Basin to Provide Unconsolidated Sediments to Astoria Fan in Pleistocene Drainage Basin 6.71 X1O5 km2 3 -2 Volume unconsolidated sediments 2.7 X 10m = 4. 1 X 10km eroded off Columbia River drainage to form fan. Assume erosion in Pleistocene (1, 5xio6yrs) or 0, 27 Cm! 10yrs. denudation rate.

11Ifthe following is assumed: 1.Interglacial periods of high stabilized sea level occupied half of a Pleistocene Epoch of 3,000,000 years. 2.For 1, 500, 000 years (one-half of Pleistocene) deposilion rate was 40 cm/103 years. 3 3.The remainder of the original 1. 675 km average thichness (1.08 km) was deposited at the present observed rate of 8 cm/10 years. Then maximum estimate of fan age (unconsolidated sediments) equals about t9, 400,000 years including correction for compaction.

VThe maximum rate would require no significant alteration for Pleistocene glacial and ijerglacial sedimentation rates since less than 1, 500,000 years would be required for deposition of unconsolidated sediments at a rate of 1. 7m/10 287

APPDIX XIV COARSE LAYER: SHALE RATIOS FOR THE CORES FROM ASTORIA FAN Uncompacted Compacted Coarse Layers:Shale % %fine* Core Coarse Fine X .35 Ratio Whole# Interchannel Upper Fan A-2 4 96 33.6 .12 1:8 B-2 6 94 32.8 18 1:5 C-2 4 96 33.6 ,12 1:8 E.-3 5 95 33.2 .15 1:2 D.2,E...2,F-2,F...4 nocoarse beds average .14 1:6 Middle Fan B-3 31 69 2442 1.28 1:1 A-32 43 57 199 2.16 2:1 C-i 19 Si 28.4 .67 1:1 C-3 39 61 21.4 1.82 2:1 D-3 19 81 28.4 .67 1:1 K-i 9 91 31.8 .28 1:3 B-4 10 90 31.5 .32 1:3 D-4 12 88 30. 8 39 1:3 K-2 13 87 30.4 .43 1:2 average 89 1:2 Lower Fan B-6 49 51 17.8 2.76 3:1 C-4 46 54 1&9 2,44 3:1 C-42 3i 69 24.2 1.28 1:1 6509-9 23 77 26.9 .86 6509-7 27 73 25.5 1,06 1:1 6509-6 37 63 22. 1 1.68 2:1 6509-16 38 62 21.7 1,75 2:1 6509-2 23 77 26.9 86 1:1 average 1q59 2:1 Channel Upper Fan D-1O 60 40 14.0 4.28 4:1 E-7 43 57 19.9 2.26 21 F-3 43 57 19.9 2.26 2:1 average 2.93 3:1 Middle Fan 6509-5 41 79 27.6 1.50 2:1 average 1.50 2:1 Lower Fan A-4A 35 65 22.7 i.58 2:1 6509-4 42 58 20.3 2.35 2:1 6509-3 36 64 22.4 1.61 2:1 6509-1 51 49 17.1 2.98 3:1 average 3, 13 2:1 *Compaction rate based on Emery and Bray (1962). an unconsolidated clay will be reduced to 35% of its original volume when it is a lithified shale.