OREGON GEOLOGY published by the Oregon Department of Geology and Mineral Industries

VOLUME 61, NUMBER 1 JANUARY/ FEBRUARY 1999

IN THIS ISSUE:

GEOLOGIC FRAMEWORK OF THE CLARNO UNIT, JOHN DAY FOSSIL BEDS NATIONAL MONUMENT, CENTRAL OREGON

REPORTS ON EARTHQUAKE SWARM AT MOUNT HOOD AND EARTHQUAKE DAMAGE TO LIFELINES IN COLOMBIA OREGON GEOLOGY Mount Hood earthquake swarm of January 1999 VOLUME 61 , NUMBER 1 JAN./FEB. 1999 During the month of January, Mount Hood experi­

,...,.".... """"""""" 1Muo'y. MMII...... ,.. W\<. ~. w __ by "" 0."", 00pWnenI oJ enced an earthquake swarm similar to past events. This Gtoqy ... _~~~,,,,,,,,,,CI __ ""'o.,,,,) swarm produced 81 recorded events, including 4 events COoverning Board between magnitude 3.0 and 3.2, Events were felt at Jacqueline G, Haggerty, Chair ...... " ...... Ent e rpri~ Timberline, Brightwood, Parkdale, and Mount Hood A~een N. Barnett ...... " ...... ", .. Portland Donald W. Christensen.. ____ . Depoe Bay Meadows. The majority of events (41) occurred on State Geologist ...... " .... " .... " ...... " .... ,' .... , Donald A. Hull Monday, January 11, followed by 9 events on January Oeputy State Geologist ...... " .... " ..... " ...... " .. John D. Beaulieu 12, 1 event on January 13, 18 events on January 14, Editor .... " ...... " ...... Klaus K,E. Neuendorf and 12 events on January 15. The earthquakes Production Assistants ..... " ...... " .... " .... ". Geneva Beck were Kate Halstead focused approximately 6 km to the south-southeast of Main OHic~; Su ite 965. 800 NE Oregon Street II ~8. Portland 97132. the summit of Mount Hood, with hypocenter depths phone (503) 731·4100, FAX (503) 731·4066. ranging from 1.1 to 9.4 km below the surface. In the Interne!; http:// sarvis.dogami, state ,0r.Us 8ak~r City Field OHic~; 1831 First Street. Baker City 97814. phone last decade, 15 other similar swarms have been located (541) 523·3133. FAX (541) 523·5992. in approximately the same area, and the largest Mark t. Ferns. Regional Geologist. recorded earthquake was a magnitude 4.0 event in Granb Pass F i~ld OHic~; 5375 Monument Drive, Grants Pass 97526, phone (541) 476-~496. FAX (541) 474-3158. December 1974. Thomas /. Wjley, Regional Geologist. The location and concentration of earthquake Mined Land Reclamation Program: 1536 Queen Ave . Sf. Albany swarms in this specific area is believed to indicate a 97321, phone (541) 967·2039, fAX (541) 967·2075, Gal)' W. Lynch. Supervisor. northwest-trending fault that is in line with the overall Internet; http://www.proaxis.com/-dogami/mlrweb.shlml regional tectonic stresses. Fault plane analysis of the The Nature of the Northwed Information Center: Suite 177. 800 NE largest event (magnitude 3.2 on January 11) indicates Oregon SI. II 5. Portland, OR 97132·2162, phone (503) 872·2750, FAX (503) 731 ·4066, Donald j, Haines, Manager. normal faulting, Internet: http://www,naturenw.org Mount Hood is considered an active volcano with the Periodicals postage paid at Portland. Oregon. Subsoiption rates: 1 potential for damaging earthquakes, eruptions, dome year. SIO: 3 years, S22. Single issues, S3, Address subscriptIon orders, renewals. and changes of address to Oregon Geology, Su ite 965. 800 collapses, pyroclastic flows, lahars, debris flows, and NE Oregon Street II 2B. Portland 97232. jokulhlaups (glacial outburst floods). Current activity Or~.{on ~.{Y is designed to reach a WIde spe

For more information, visit the websites of the U.S. Cover photo Geological Survey Cascades Volcano Observatory: The Palisades, a prominent cliff in the Clarno Unit of http·//vulcan.wr.usgs.gov/Volcanoes/Hood/frame­ the John Day Fossil Beds National Monument. formed by the erosion of massive debris-flow depOSits. Article work.html; and the University of Washington Geo­ beginning on next page describes the geology of this physics Program: http://www.geophys.washington.edu region. Photo courtesy of Erick A. Bestland. / SEIS/ PNSN / HOOD/

2 OREGON GEOLOGY, VOLUME 61 , NUMBER I, JANUARY/FEBRUARY 1999 Geologic framework of the Clarno Unit, John Day Fossil Beds National Monument, central Oregon

1 ;/ I "d·' b~ EA. Best/and, PE Hammond, D.L.S Blackwell, M.A. Kays, GJ Retallack, an j Stimac

ABSTRACT conglomerates but have, in addi­ These fossil leaf beds are thus earliest Two major geologic events are tion, fluvially reworked conglomer­ Oligocene in age, similar in age to the recorded in the Eocene-Oligocene ates, reworked tuff beds, a distinc­ type locality of the Bridge Creek flora volcaniclastic strata, volcanic fJows, tive amygdaloidal basalt flow (43.8 in the Painted Hills area. and paleosols of the Clarno Unit of ± 0.5 Ma), and the fossil site known the John Day Fossil Beds National as the "Nut Beds." Both units accu ­ INTRODUCTION Monument. A major plate-tectonic mulated on volcanic aprons in re­ The scenic high desert of north­ reorganization in the Pacific North­ sponse to volcanism (synvolcanic central Oregon contains a colorful west at about 40-42 Ma shifted vol­ sedimentation) in an area of irregular volcanic and alluvial sequence of Ter ­ canism from the Clarno volcanic topography, including hills of a pre­ tiary age (Figure 1). For the protection province, represented by Clarno For­ existing dacite dome. and appreciation of the geologic and mation andesitic flows and debris Above the conglomerates are paleontologic resources in this area, flows, to the Cascade arc, repre­ thick but discontinuous red clay­ three " Units" (Sheep Rock, Clarno, sented by John Day Formation tuffa­ stones (claystone of Red Hill), which and Painted Hills) were established in ceous deposits and ash-flow tuffs. record a long period of volcanic the John Day Fossil Beds National Evidence of the second major geo­ quiescence (2-4 m.y.), slow flood­ Monument. The strata exposed in the logic event comes from paleosols and plain aggradation, and long periods National Monument record two im­ fossil remains of plants and animals in of soil formation. The Red Hill pale­ portant geologic events: (1) The these two formations and indicates a osols and fossil plants from the Nut change from Eocene Clarno arc vol ­ global paleoclimate change centered Beds, which directly underlie the red canism, represented by the Clarno around the 34-Ma Eocene-Oligocene beds, are evidence of a climate that Formation, to late Eocene Cascade arc boundary, when the earth changed was subtropical and humid. Discon­ volcanism and John Day Formation from a tropical Eocene "hothouse" to form ably overlying the red beds are back-arc deposition is recorded in a temperate Oligocene "icehouse." gray-brown siltstones and conglom­ these two formations. (2) A dramatic In the Clarno Unit area, the lower erates of the Hancock Mammal paleoclimatic change occurred across part of the Clarno Formation consists Quarry, which have yielded a the Eocene-Oligocene transition dur­ of structurally domed debris-flow titanothere-dominated fossil fauna ing which conditions changed in cen­ conglomerates, andesite flows (51.2 (Duchesnean North American land tral Oregon from subtropical humid to ± 0.5 Ma), and a dacite dome (53.5 Mammal Age). semiarid temperate climate. The mag­ ± 0.3 Mal. both onlapped by less The Clarno Formation is overlain nitude and timing of these paleocli ­ deformed debris-flow conglomerates, abruptly by an ash-flow tuff of the matic changes as well as the strati­ andesite flows (43.4 ± 0.4 Mal. and basal John Day Formation (39.2 ± graphic positions and ages of fOSSil red beds. The onlapping conglomer­ 0.03 Ma). A major lithologic bound­ sites have been worked out from de­ ates are composed of two widespread ary occurs in the lower John Day tailed mapping and section-measuring units that are dominated by debris Formation between kaolinite- and in the Clarno Unit area of paleosols flows, are separated by red claystones iron-rich claystones (paleosols) of (ancient soils), fossiliferous beds, and (paleosols), and are each approxi­ the lower Big Basin Member (upper radiometrically dated tuff beds . This mately 60 m thick. The lower unit, Eocene) and smectite and tuffaceous mapping has also revealed a domal conglomerate of The Palisades, con­ claystones of the middle Big Basin volcanic edifice of Clarno age that was sists of channel and floodplain debris­ Member (lower Oligocene). An age emplaced early in the accumulation of flow conglomerates and lahar runout determination of 38.2 ± 0.07 Ma on the formation and was subsequently deposits. The overlying conglomer­ a tuff in the lower Big Basin Member onlapped by volcaniclastic deposits. ates of Hancock Canyon also contain and a 33.6 ± 0.19 Ma age determi­ The purpose of this paper is to channel and floodplain debris-flow nation for the Slanting Leaf Beds in provide a geologic and paleoenviron­ the middle Big Basin Member support mental summary of the Clarno and 1 Department of Geological Sciences, University the interpretation that the contact lower John Day Formations in the of Oregon. Eugene OR 97403-1272. between these two members is close Clarno Unit area of the John Day 1 Department of Geology, Portland State Uni­ versity, Portland OR 97207-07501 . to the Eocene-Oligocene boundary. Fossil Beds National Monument. Thfs

OREGON GEOLOGY, VOLUME 61 , NUMBER I, JANUARY/F EBRUARY 1999 3 74-207 H)7 208 ~--Heppner74 97

19

197 Shaniko Fossil 21 ~_1 1 CLA RNO UN IT an e op~ ..J l 207 218 " JOliN DA Y FOSSILIlEDS• NATIONAL MO{'iUMENT 97 207 Kimberly PAINTED ~LLS UN IT • 19 SH EEP ROCK UNIT 26 97 Dayville 26---0: 26 0 10 jO 30 mi Mt. Vernon I~.. ~,~~I",,,~,~,,~,,,,' Redmond r W 10 30 40km

Figure 1. location map of north-central Oregon showing units of the John Day Fossil Beds National Monument and major access roads. paper represents a synthesis of the The University of Oregon Field the National Monument. combined efforts of three different Camp has been mapping in this area The informal stratigraphic subdivi­ groups that have worked extensively since 1985 and is developing a re­ sions of the Clarno and John Day in the Clarno area . A three-year study gional map of the Clarno and John Formations presented here are based by Bestland and Retallack for the Na­ Day Formations along the north side on rock type and stratigraphic posi· tional Park Service generated an ex­ of the Blue Mountains uplift. Port· tion (Figures 2 and 3). New strati· tensive and detailed data base of land State University Geologic Field graphic units identified are all infor­ mapping, volcanic and paleosol stra· Methods students and staff have mal in accordance with rules about tigraphy, new 40Ar/9Ar age determi· been mapping in this area since such units in the North American nations, and discovery of new fossil 1988 and have concentrated on de­ Commission on Stratigra-phic Nomen· sites (Bestland and Retallack, 1994a). tailed lithostratigraphic mapping of clature (1983). The new subdivisions

4 OREGON GEOLOGY, VOLUME 61 , NUMBER I, JANUARYIFEBRUARY 1999 will be denoted by lower case such as

"lower Big Basin Member. H

GEOLOGIC SETTING Clarno Formation The Clarno Formation is a thick "italian hill" lui! jrnb, middle Member section (up to 6,000 ft (1 ,800 mn of "sLanting lear"" iliff " largely andesitic volcanic and volcani­ Member F tuff clastic rocks of Eocene age that crops out over a large area of north-central Ill. lower Big Oregon. Th e formation was named Mamaf B andeslll Lava by Merriam (1901 a,b) for exposures of volcanic rocks at Clarno's Ferry, now a bridge over the John Day River west of the National Monument boundary. The Clarno Formation dis­ cat!, andesite of Horse MIn conform ably overlies pre "Tertiary of "red h.ill" ro cks that include highly deformed metasediments of Permian to Trias­ sic age (Hotz and others, 1977), Cre­ ella, and&site of "Hancock" canyon taceous marine rocks in the Mitchell area and sedimentary rocks of uncer­ :nb ~ <43.8 ""' 1 tain age mapped as Cretaceous sedi­ eli!!s mentary rocks by Swanson (1969) ""~~l:~ff.E~~~ , ~ "" ' p" ..,,,' and interpreted as Paleocene or Eocene sedimentary equivalents of the Herren Formation (Wareham, 1986; Fisk and Fritts, 1987). The for­ mation is overlain for the most part lower Clarno Fonnation OOfICOnformity by the John Day Formation. Where , -HlUlCock" dacite dome the formation formed ancient vol­ canic highlands, younger rock units such as the Miocene Columbia River Fi gure 2. Composite stratigraphic section of the upper Clarno and lower B.asalt Group, Miocene Mascall Forma­ John Day Formations in the Clarno Unit of the John Day Fossil Beds National tion, Miocene-Pliocene Rattlesnake Monument. Diagram shows inform ally recognized stratigraphic units and Formation, and Miocene-Pliocene corresponding age determinations. For explanation of symbols to units, see Deschutes Formation, disconformably geologic map of Fi gu re 3. Additional symbols are: brn (brown); cgl overlie the Clarno Formation. (conglomerate); clst (claystone); ss (sandstone); st (siltstone); and wh (white). The Clarno Formation consists of nonmarine volcanic and volcaniclastic units that range in age from middle to Rogers, 1991; White and Robinson, John Day Formation late Eocene, some 54 to 39 m.y. old 1992; Bestland and others, 1995). The John Day formation consists of (Evernden and James, 1964; Evern­ The calc-alkaline volcanic rocks rep ­ rhyolitic ash-flow tuff and dacitic to den and others, 1964; McKee, 1970; resent subduction-related andesitic rhyodacitic tuffs and alluvial deposits Enlows and Parker, 1972; Rogers and volcanism , probably on thin conti­ of latest Eocene, Oligocene, and early Novitsky-Evans, 1977; Manchester, nental crust (Rogers and Novitsky­ Miocene (39-18 m.y.) age (Wood­ 1981, 1990, 1994; Fiebelkorn and Evans, 1977; Rogers and Ragland, burne and Robinson. 1977; Robinson others, 1982; Vance, 1988: Walker 1980; Noblett, 1981 ; Suayah and and others, 1990; Bestland . 1997; and Robinson, 1990; Bestland and Rogers. 1991). White and Robinson Bestland and others, 1997). Robinson others, 1997). Volcanic plugs, lava (1992) evaluated the sedimentology and others (1984) interpret these pri­ flows, and lahars, with convergent­ of the volcaniclastic deposits on a mary pyroclastic, alluvial and lacus­ margin andesitic compositions and regional scale and interpre ted the trine deposits as the distal deposits textures, indicate accumulation in and strata as nonmarine volcanogenic from vents to the west in the Western around andesitic volcanic cones deposits that were deposited in Cascades and from more proximal (Waters and others, 1951: Taylor, alluvial aprons and braidplains that vents now buried or partially buried 1960: Noblett, 1981: Suayah and flanked active volcanoes. by the High Cascade volcanic cover.

OREGON GEOLOGY, VOLUME 61 . NUMBER I, JANUARY/FEBRUARY 1999 5 120025'00;;;,'/-.,-____...,,---, GEOLOGIC MAP OF CLARNO UNIT OF JOHN DAY FOSSIL BEDS NATIONAL MONUMENT AND VICINITY, WHEELER COUNTY OREGON Geology by EA. Btstland. P. E. Hammond, D.L.S. Blackwell, M.A. Kays, G.J. Retallack, 1. Stimac, and Portland Slate University geology students, 1988- 1994

o j I mi l~---~~:---~'~"'~krn Sc:aIe: -1 :34.250 N MN A

I2702T3O"

•

B

~~~~~~~~--~~~~:J~~~~~2:~£L,,"~~,,~w=·~~~~------~

Fi gure 3. Informal geologic map of the Clarno Unit of the John Day Fossil Beds National Monument and vicinity (modified from Bestland and Retallack, 1994a; unpublished mapping by P.E . Hammond and Portland State University students; and unpublished mapping by M.A. Kays, D.l.S. Blackwell, J. Stimac, and E.A. Bestland).

6 OREGON GEOLOGY, VOLUME 61 , NUMBER I, JANUARY/fEBRUARY 1999 Thus, the transition between the tuff beds), and Haystack Valley Mem­ EXPLANATION Clarno and John Day Formations ber (tuffaceous conglomerates). We Rock units are symbolized here and on records a late Eocene westward jump report stratigraphic subdivisions of the map without the usual period des­ of the subduction zone in the Pacific the John Day Formation in the Clarno ignation: in this case, "Q" for some Quaternary surficial units and "T" for Northwest and a corresponding Unit area following both the A­ all other, Terti ary, units. change from Clarno andesitic volcan­ through-I system of Peck (1964) and ism to Cascade volcanism and John the identification of formal members Surficial deposits Day back-arc basin deposition. of the eastern facies by Fisher and The John Day Formation is divided Rensberger (1972) as modified by Re­ , Alluvium into eastern, western, and southern tallack and others (1996) and Best­ I, Landslide facies on the basis of geography and land and others (1997). t, Talus lithology (Woodburne and Robinson, P Pediment 1977; Robinson and others, 1984). Physiography Bedrock units The Blue Mountains uplift separates In the John Day River canyonlands "b Columbia River Basalt Group the western and eastern facies; it also of north-central Oregon, each of the John Day Formation restricted deposition of much of the three major geologic divisions has a jmb Middle and upper Big Basin members coarser grained pyroclastic material to distinctive geomorphic expression jfb Member F basalts the western facies. (Figure 4): (1) Resistant andesite and jib Lower Big Basin Member claystones The western facies is informally debris-flow units of the Clarno Forma­ ift White tuff of member F divided into members A through I on tion form dissected hilly canyonlands the basis of laterally extensive ash­ that are largely covered by thin soils. jba Member B basaltic andesite flow tuffs sheets (Peck, 1964; Swan­ (2) The much finer grained and less jat Welded tuff of member A son and Robinson, 1968; Swanson, volcanically dominated John Day For­ Clarno Formation 1969). This facies contains coarse­ mation forms broad benches that are ,mq Siltstone of Hancock Mammal Quarry grained volcaniclastic deposits, commonly covered by coarse collu­ "h Andesite of Horse Mountain welded ash-flow tuff sheets, and a vium and landslide debris originating Upper andesite of Horse Mountain variety of lava flow units, including from resistant units upslope. (3) Cap­ "" trachyandesite flows of member B, ping many of the canyons and form­ "h Claystone of Red Hill rhyolite flows of member C, and alka­ ing impressive cliffs are the resistant ,h, Andesite of Hancock Canyon line basalts of member F. The Clarno rocks of the Columbia River Basalt '" Conglomerate Unit area is in the western facies, Group. Another prominent feature of ," Tuff of Currant Creek where the John Day Formation has this area is the thick and resistant ,hb Basalt of Hancock Canyon been mapped in reconnaissance style welded tuff of member A of the basal "h Conglomerate of Hancock Canyon by Robinson (1975), who used the John Day Formation, which forms a cawf Andesite of West Face Cliffs stratigraphic divisions of members A cuesta that can be traced throughout through I. the area. The John Day Formation Conglomerate of The Palisades "P The eastern facies is divided into above this marker bed can be divided "P Andesite of Pine Creek four formal members (Fisher and into·a lower and upper part on the d Lower Clarno Formation Rensberger 1972). From bottom to basis of geomorphic expression. The ,d Hancock dacite dome top they are Big Basin Member (red lower part consists of clayey and claystones). Turtle Cove Member kaolinite-rich strata of the lower Big -- - (green and buff tuffaceous clay­ Basin Member, which weather to form --- Contact stones), Kimberly Member (massive a gently-sloping bench covered with ---- Indefinite contact ______Clarno FormatioD'--"7=c_ I_John Day Formatioo_1 Iron Mtn Strike and dip of bedding local CoIumb"i"c::::=:'::: Horse Mtn ~~~ 11 landSlidede~ & ~t I Fault, showing displacement: :. :." _ clifted dissected canyons pediments P Iments cliffs - slopes Big Basin bench .~ _ U=upthrown side, andesitic I~\I" andtIows __ , ,', """. ",""'-- D=downthrown side '~ ...... ~~~Oc ...... ~~%~ ~.. ,'.~ 9"_'~~ .... .If~ Indefinite fault ... ~~~ ...... 1 --.. , ~ Fold a ~ is, showing plunge Fi gu re 4. Sketch cross section of the Clarno area, i1Justrating the physiographic Anticline differences between the dissected canyons of the Clarno Formation, the broad, gently sloping benches of the lower John Day Formation, and the prominent cliffs x, Syncline of the Columbia Ri ver Basalt Group.

OREGON GEOLOGY, VO LUME 61 , NUMBER I, JANUARY/FEBRUARY 1999 7 thick clayey soil. The Oligocene part Formation and Columbia River Basalt northeast-plunging folds (Figure 3). of the John Day Formation contains Group have slid over clayey soils, This orientation is parallel to the elon­ tuffaceous strata rich in smectite clay confusing some of the distribution of gation of the Blue Mountains in that weather into steep badlands and basalt units (see map by Robinson, northeastern Oregon. Faults, on the sloping hills, 1975). Pediment surfaces and collu­ other hand, strike west to northwest. The erosional history of the area to vial soils dominated by basaltic frag­ generally in a direction normal to fold its present-day topography began in ments veneer much of the land­ axes. They commonly show right­ the late Miocene after cessation of scape. Small alluvial fans and dis­ lateral strike-slip movement with dis­ Columbia River Basalt Group volcan­ sected fanglomerate deposits of Qua­ placements less than a few hundred ism and deposition of the mid­ ternary age are common occurrences meters. Deformation was caused by a Miocene Mascall Formation. A major proximal to small canyons draining northwestward-directed compressive tectonic break occurred in north­ steep terrain of the Columbia River (shear) stress which folded the strata central Oregon between the Mascall Basalt Group. Most of these Quater­ and moved fault-bounded southern Formation, dominated by fine-grained nary deposits overlie the John Day Clarno blocks westward, relative to alluvium, and the disconformably over­ Formation. The fanglomerates contain the northern blocks. Because dips of lying late Miocene Rattlesnake For­ caliche-cemented paleosol horizons. the strata decrease upward strati­ mation, dominated by fanglomerates graphically, deformation was under­ of basaltic composition. Thus, faulting Structure way during deposition of Clarno For­ and uplift of central Oregon must have Strata of the Clarno and John Day mation, between 55 and 45 Ma, and begun sometime in the late Miocene. Formations and overlying flows of continued past the outpouring of In the Clarno area, landslides con­ the Columbia River Basalt Group Columbia River Basalt Group lava at sisting of large and seemingly coher­ are gently to moderately folded, 16-15Ma. ent blocks of basalt from the John Day forming broad, open, generally

CLARNO FORMATION LITHOSTRATIGRAPHIC UNITS (CLARNO AREA) In the Clarno Unit area, the Clarno and of local extent (Hanson, 1973, 1994a). The overlying pebbly clay­ Formation contains laterally extensive 1995) and are exposed in a struc­ stones contain boulders exclusively of and mappable lithostratigraphic units tural dome or anticline west of Han­ weathered, altered hornblende (Figures 2 and 3). These units are of cock Field Station (Figure 3). The dacite. The claystones are interpreted three types: (1) andesitic debris-flow anticline is a structural window into as well-developed paleosols of the packages, (2) andesite lava flows, and lower Clarno Formation strata that Pswa pedotype (Bestland and Retal­ (3) claystones. Smaller scale litho­ have been onlapped by later Clarno lack, 1994a) that developed on an stratigraphic units, such as basalt flows Formation deposits. The strati­ igneous body and incorporated collu­ or thin andesite flows, tuff beds, and graphic position and relationship of vial debris (dacite clasts) from the minor red beds, were used to charac­ these older deposits with the dacite underlying dacite. Thus, the dacite terize and help identify larger strati­ body are not clear. body was an erosional feature that graphic packages. Of the three litho­ was mantled by colluvium and soils. stratigraphic types, the debris- and Hancock dacite dome (unit Tcd) andesite-flow units constitute the A plagioclase-hornblende dacite Andesite of Pine Creek (unit Tcap) majority of the cliffs along the John porphyry is exposed in the hills and The base of the stratigraphically Day River in the area south of Clarno gullies to the northeast of Hancock coherent section in the Clarno Unit bridge along the John Day River and Field Station (Figure 3, unit Tcd). The area is a thick andesite flow referred along the western part of Pine Creek. dome-shaped rock body is perva­ to as the andesite of Pine Creek sively altered and in the northern (Figure 5a). The lava flows consist of Lower Clarno Formation (unit Tel) part of its outcrop consists of com­ dark-colored pyroxene-plagioclase an­ Some older debris flows underlie pact breccia. Massive, nonbrecciated desite, and a sample from the west the main Clarno Formation sequence dacite is exposed in the bottom of lobe was dated at 51.2 ± 0.5 Ma in the Clarno Unit area (Figure 3). gullies, from which a sample was (Table 1, sample no. 93603). West of These debris flows consist of a se­ dated at 53.6 ± 0.3 Ma (Table 1, The Palisades a single flow (>50 m quence of boulder-sized, matrix­ sample no. 93602). Stratigraphic thick) occurs in two lobes, judging by supported conglomerates that are ex­ sections of strata directly overlying their similar lithologies and chemical posed just to the west of Hancock this igneous body do not show intru­ composition. These lobes terminate Canyon and are referred to as lower sive features such as baking, veining, along the north side of Highway 218 Clarno conglomerate. These debris­ hydrothermal alteration, and miner­ and extend northward no more than flow deposits are of uncertain affinity alization (Bestland and Retallack, 600 m into the Clarno Unit. The an-

8 OREGON GEOLOGY, VOLUME 61 , NUMBER I, JANUARY/FEBRUARY 1999 desite flows have a very irregular up­ per surface that consists of breccia mantled by a weathered red saprolite. Paleorelief of this unit is best ex­ posed in cliffs along Pine Creek be­ tween Th e Palisades and the entrance to Hancock Field Station, where more than 40 m of paleotopography is on­ lapped by debris flows over a lateral distance of 200 m. Pockets of red and white claystones (paleosols) are pre­ served between the andesite and overlying debris flows and were mapped separately (Bestland and Re­ tallack,1994a). Conglomerate of The Palisades (unit Tcep) Onlapping the irregular surface of the andesite of Pine Creek is a thick (55 m) sequence of debris flows dom­ inated by clasts of andesitic composi­ tion (Figures 5b,c). The conglomerate of The Palisades weathers to form the spectacular hoodoos along Pine Creek and in the lower part of the West Face Cliffs along the John Day River (Figures Sa-c), Most of the conglom· erate is matrix-supported, moderately clast- rich, laterally continuous, and interpreted as floodplain debris flows (in the sense of Scott, 1988). The Palisade cliffs contain numerous clast­ rich , channelized debris flows. Some are clast supported at their base. Hy­ perconcentrated flood flow deposits (in the sense of Nemec and Muszyn­ ski, 1982; and GA Smith, 1986) are common at the base of debris flows where they grade into debris-flow deposits. Well exposed at approxi ­ mately the middle of this unit are several thin, green, clayey paleosols with wood fragments and leaf im · pressions (Figure 5c). To the east of Cove Creek, con­ glomerate of The Palisades on laps, thins, and pinches out against an ­ desite of Pine Creek. Mantling the conglomerate of The Palisades is a saprolite horizon that is overlain by Figure 5. Photographs of West Fa ce Cliffs: (a)-View to the south toward Horse brown and red claystones (paleosols) . Mountain, showing lithostratigraphic units in the Clarno Formation. (b)-View to These claystones erode to form a the north at West Face Cliffs. (c)-Debris- flow deposits and paleosols in conglom­ bench on the mesa between Hancock erate of The Palisades in West Face Cliffs. Rock unit symbols as in map of Figure 3, Canyon and Indian Canyon . Th is but "T" added and Tcam=cawf. bench is also present on the north and

OREGON GEOLOGY, VOLUME 61 , NUMBER I, JANUARY/FEBRUARY 1999 9 west sides of Horse Mountain and site, a 7-m-thick by 300-m-wide 1, sample no. 93613). The basalt can along the canyon walls of Cove Creek. lens of silica-cemented sandstone be mapped from the Hancock Field and conglomerate that contains pro­ Station area to the Gable, is thickest Andesite of West Face Cliffs lific floral remains. Radiometric age (23 m) in the West Face Cliffs, but is (unit Tcawf) determinations on the Nut Beds and not present east of Indian Canyon This thick andesite is locally present the Muddy Ranch tuff (also known (Figure 3). This basalt flow can be in the southern part of the project as the "Rajneesh Tuff " and named traced along the cliffs of the John Day area south of Clarno along the John in this paper the "tuff of Currant River south to Melendy Ridge, a dis­ Day River (Figure 5a). Here, the unit is Creek," unit cct in Figure 3) are tance of 14 km. The flow is very exposed in the lower half of the approximately 44 Ma; c.c. Swisher vesicular at its base, indicating that it monolithic buttes on the west side of obtained a date of 44 Ma from a flowed over moist terrain, where heat the river (Hills 2441 and 2373, sec. 9, plagioclase separate from a re­ from the lava vaporized the moisture, T. 8 S., R. 19 E.) and consists of blocky, worked crystal tuff in the Nut Beds, and the steam penetrated upward dark-colored, pyroxene-plagioclase using the 4°Ar/l9Ar method (oral in to the still molten lava. locally, andesite. At the base of Hill 2441 communication, 1992), and Brent these gas holes are filled with agate. along the John Day River, the unit fills Turrin (for Manchester, 1990, 1994) a paleovalley cut into the conglomer­ used the same method on plagio­ Claystone of Red Hill (unit Tcrh) ates of The Palisades. In the West Face clase of the Nut Beds for an age of In the Clarno Unit area, a thick Cliffs, the unit is clearly onlapped by 43.76 ± 0.29 Ma. Vance (1988) sequence of reddish and grayish­ conglomerate of Hancock Canyon. obtained dates of 43.6 and 43.7 Ma purple claystones overlies the con­ from fission track of zircon crystals glomerate of Hancock Canyon Conglomerate of Hancock Canyon in the Nut Beds and 44 Ma in the (Figure 7a,b). The unit is 59 m thick in (unit Tcch) Muddy Ranch tuff near the Gable the Red Hill area (Figure 2) but thins Overlying both the red claystone (Figure 3). The Muddy Ranch tuff is dramatically to the east. In the cliffs beds at the top of the conglomerate stratigraphically below the Nut on the west and north side of Horse of The Palisades and the andesite of Beds. Many large, well-preserved Mountain; only a reddish saprolite West Face Cliffs is the conglomerate permineralized tree trunks and with thin clay layer is present at this of Hancock Canyon (Figure 6). like limbs of Cercidiphyllum (katsura) stratigraphic level. The unit at Red Hill the conglomerate of The Palisades, and Macgil7lfea (sycamore) are in contains a lower reddish paleosol se­ clasts in this unit are principally of the conglomerates of Hancock quence of very deeply weathered andesitic composition. This unit in­ Canyon. Ultisol-like paleosols (lakayx pedo­ cludes tuffaceous beds and a distinc­ type) and an upper, less well devel­ tive basalt flow but is dominated by Basalt of Hancock Canyon oped Alfisol-like paleosol sequence matrix-supported boulder-debris flows. (unit Tchb) (Luca pedotype, Retallack, 1981; G.s. Deposits of this unit onlap the Han­ A distinctive and widespread Smith, 1988;). A stony tuff bed above cock dacite dome. In the Clarno Unit amygdaloidal basalt flow occurs the lowest luca paleosol approxi­ area, the conglomerate of Hancock stratigraphically in the upper half of mately divides the two paleosol se­ Canyon can be distinguished from the the conglomerates of Hancock quences and has been dated at 42.7 conglomerate of The Palisades by Canyon (Figure 6c). The basalt is ± 0.3 Ma (Table 1, sample no. their more prominent bedding, less holocrystalline, contains common 93653). coarse-grained and massive texture, plagiodase and pyroxene grains, dis­ Conglomeratic beds are locally pres­ and common thin tuff interbeds. plays pahoehoe flow structures and ent in the claystones. At the southern The conglomerate of Hancock local columnar jointing, and has tip of the Gable, a thick (18-m) coarse­ Canyon contains the Nut Beds fossil been dated at 43.8 ± 0.5 Ma (Table grained conglomerate body (unit

Table 1. 4OAr/'Ar incremental heating ages for rocks from the Clarno Formation, eastern Oregon, by R.A. Duncan

Sample Total fusion Plateau Age 1 19Ar % Isochron age oo Ar/l~A r M. Material Age (Ma) (Ma) of total (Ma) N' intercept ~ 1s J'

93634 Andesite (plagioclase) 45.1 43.4 :!: 0.4 70.3 44.1 :!: 1.9 6 306.9 ~ 14_6 0 .001658 93653 Tuff (plagioclase) 43.0 42.7 :!: 0.3 91 .6 43.7 :!: 0.6 5 289.8 ~ 5.8 0.001403 91613 8asalt (plagioclase) 43.2 43 .8 :!: 0.5 74.3 45.2 ~ 8.1 5 217.4 ~ 264.9 0.001349 93603 Andesite (whole rock) 50.8 51 .2 ~ 0.5 62.4 48.3 ~ 4.4 6 233.6:t 339.2 0.001555 93602 Dacite (plagioclase) 57.2 53.6 ~ 0.3 44.4 56.1 ~ 0.6 5 289.8 :t 2.2 0.001680

1 Plateau ages are the mean of concordant step ages (! J = number of steps), weighted by the inverse of their variances. J is the neutron fluence factor. determined from measured monitor 4/JAr/,9Ar .

10 OREGON GEOLOGY, VOLUME 61, NUMBER I, JANUARYIFEBRUARY f999 Figure 7. Photographs of upper Clarno Formation units. (a)-View to the north showing Red Hill and lithostrati­ graphic units in upper Clarno Formation (Nutbeds are In the upper part of the conglomerate of Hancock Canyon. (b)-View to the north showing Red Hill East and lithos· tratigraphic units exposed in the badlands. Rock unit sym­ bols as in map of Figure 3, but "T" added and Teq "'emq.

Figure 6. Photographs of The Palisades and Hancock The claystones of Red Hill are prone to landslides. Canyon . (a)-View to the west showing the conglomerates Most landslides in the area occur where thick exposures of The Palisades overlain by bench·forming claystone unit of these claystones are overlain by the welded tuff of which in turn is overl ain by conglomerates of Hancock member A of the basal John Day Formation. Good exam· Canyon. (b)-View to the east showing the conglomerate pies of these landslides occur on the east side of Indian of Hancock Canyon overlain by claystone of Red Hill and Canyon . The landslides do not appear deep seated; the the upper andesite unit. (c)-View to the east showing the coherent blocks of member A form shallow, rocky slides. margin of the dacite dome and onlapping strata. A series of trenches was dug down to bedrock at this location and Andesite of Horse Mountain (unit Teah) documented the onlapping nature of a series of colluvial paleosols onto the dacite igneous body. Rock unit symbols This thick andesite unit is extensively exposed in the as in map of Figure 3, but " T" added. Clarno area where it caps much of Horse Mountain (Figure 5a,b) and has been dated at 43.4 ± 0.4 Ma (Table 1, sample no. 93634). The unit consists of platy to blocky Tag) is interbedded with red claystones. The conglomer­ andesite that varies from pyroxene-plagioclase andesite ates are clast supported and contain rounded clasts of to very porphyritic plagioclase dacite with traces of andesite and amygdaloidal basalt. They cut into red hornblende. Along the west and north side of Horse Moun· claystones and underlying units of the conglomerate of tain, the unit overlies a 2-m-thick red saprolite developed Hancock Canyon. on the amygdaloidal basalt flow (unit Tchb) in the con-

OREGON GEOLOGY, VOLUME 61, NUMBER I, JANUARYlfEBRUARY 1999 " glomerate of Hancock Canyon. tified by bulk rock geochemistry locally present in the Red Hill-Indian Ramplike flow structures are common (Bestland and Retallack, 1994a). Canyon area (Figure Sa) . A diverse in lava flows exposed in the West lithologically and geochemically and important vertebrate fauna has Face Cliffs. The base of the unit dips similar andesite crops out in the been excavated from the Hancock gently to the west. probably follow­ upper part of Hancock Canyon, Mammal Quarry, located stratigraphi­ ing a paleoslope. where it underlies the siltstone of cally in the uppermost Clarno Forma­ An upper andesite (unit Tcau) is Hancock Mammal Quarry. In bad­ tion and below member A of the John recognized above the andesite of land exposures to the east of Red Day Formation (Hanson, 1973, 1989, Horse Mountain, based on strati­ Hill, a saprolitized andesite breccia 1995). Pratt (1988) described graphic position and lithology. On the can be traced into coherent expo­ Inceptisol-like paleosols from the roiling top of the western part of su re of this upper andesite unit. Hancock Mammal Quarry. 8y her in­ Horse Mountain, a plagioclase phyric, terpretation, the fOSSil remains accu­ basaltic andesite flow is exposed Siltstone of Hancock M ammal mulated as carcasses and were disar­ above a 1 - to 3-m-thick red claystone Quarry (unit Tcmq) ticulated in a fluvial point bar. unit (paleosols) and below member A The tan, dayey siltstones and of the basal John Day Formation. This cobble conglomerates of the Han­ andesite has been mapped and iden- cock Mammal Quarry beds are only

JOHN DAY FORMATION LITHOSTRATIGRAPHIC UNITS (CLARNO AREA)

In the Clarno Unit area, the John Welded tuff of member A (unit pyramidal quartz crystals but less Day Formation has been mapped and Tjat}-Rhyolitic pyroclastic volcan­ lithic fragments than the lower stratigraphically subdivided by Robin· ism of the John Day Formation is first densely welded part. son (1975) following Peck's (1961, recorded in north -central Oregon by Member B basaltic andesite (unit 1964) informal subdivision of the an ash-flow tuff now redated in the Tjba)-In the Clarno Unit area, dis­ John Day Formation on the basis of Clarno area at 39.2 Ma and by a tinctive aphanitic basaltic andesite distinctive pyroclastic and lava flow 39.7 Ma date from this tuff in the flows overlie member A. Red clay· units. In this paper, these pyroclastic Painted Hills area (Bestland and oth­ stones are 10caJJy present between and lava flow units are recognized ers, 1997). This basal ash-trow tuff the two units. The flows consist of and given the names defined by Peck sheet is extensively exposed in the aphanitic to sub·glassy basaltic an · (1964) and mapped by Robinson western fades (Peck, 1964; Robin­ desite that weathers into cobble-sized (1975); however, only distinct litho­ son, 1975) where it is useful for blocks. These basalts correlate with logic units were mapped in the Clarno delineating the Clarno surface at the the member B trachyandesites of Peck Unit area. These volcanic units, along onset of John Day volcanism (Figu re (1964) and (Swanson, 1969) and with the interbedded claystones, la­ 8a) have also been mapped in the Clarno custrine shales, and tuffs, are here A lower, densely welded tuff Unit area (Robinson, 1975). Peck assigned to eastern facies members of forms prominent outcrops in the (1964) identified 460 m of very dark the John Day Formation (Fisher and Clarno Unit area and is approxi· gray·aphanitic flows of trachyandesite Rensberger, 1972). mately 30 m thick. A perlitic vitro­ in the Ashwood area. In the Clarno phyre occurs locally at the base and Unit area, a 21-m-thick columnar­ l ower Big Basin Member is best exposed in roadcuts at the jointed basaltic andesite lava flow (unit Tjlb) Gable. At the very base of the ash­ crops out at the head of Indian The lower 8ig 8asin member in the flow tuff are unwelded tuff deposits, Canyon and is the thickest occurrence Clarno Unit area includes all lithos­ some containing accretionary lapilJi of member B in the area. Other smarr tratigraphic units from and including and plant rema ins (Figure 8b). lithic exposures are scattered throughout the welded tuff of member A of the fragments are common in the lower the area and are recognizable by their basal John Day Formation up to a tuff as are bi-pyramidal (beta) quartz aphanitic texture and a weathering truncation surface marked in places crystals. An upper, weakly welded to character that produces small, cobble­ by conglomerates and sandstones of unwelded part of the ash-flow tuff, sized blocks-similar to Peck's (1964) probable Oligocene age (Figure 2) . approximately 25 m thick, crops out description of member 8. A set of These sandstones and conglomerates extensively in the Clarno Unit area, basaltic andesite intrusions of this are exposed in gullies to the west of where it commonly forms the dip lithology forms a smarr hill between the Slanting leaf 8eds which they slope on the member A cuesta. This Hancock Canyon and Indian Canyon stratigraphically underlie. unit also contains abundant bi- (NE V~ sec. 26, T. 7 S. , R. 19 E.). The

12 OREGON GEOLOGY, VOLUME 61 , NUMBER I, JANUARY/F EBRUARY 1999 Figure 8. Photographs of lower John Day For­ mation. (a)-View to the east showing the Han­ cock Mammal Quarry area and the welded mem­ ber A tuff (unit Tjat) of the basal John Day Formation overlying the Hancock Mammal Quarry beds (unit Tcmq) and the conglomerate of Han cock Canyon (unit Tech). (b)-Carb onized plant debris and accretionary lapilli from the unwelded base of the member A tuff. (c}-Tuffa­ ceo us claystone of the lower Big Basin member overl ain by siltstone channel depOSits. rock contains pebble-sized cognate xenoliths of gabbro. Geochemically, lava flows and dikes are very similar in composition (Bestland and Retal­ lack, 1 994a). White tuff of member F (unit Tjft)-A massive, white vitric tuff approximately 1-3 m thick is widespread but poorly exposed in the lower John Day Formation in the Clarno Unit area. This tuff is interbedded with clayey red beds of the lower Big Basin Member and has been referred to previously as the member F tuff. This vitric tuff was dated at the Whitecap Knoll (=White Knoll on map in figure 3) locality at 38.2 Ma (Bestrand and others, 1997). Getahun and Retallack (1991) identified an Alfisol-like paleosol (luca pedotype) directly below this tuff at Whitecap Knoll. Robinson and Brem (1981) identified a massive, white, vitric tuff located in a road cut just west of the Clarno Grange Hall on Highway 218 as the base of member F in this area. However, recent 4f)Ar/'1Ar age determinations on the member F C tuff in its type area in the western facies indi- cate an early Oligocene age (GA Smith, oral comm un ication. 1996; Smith and others, 1996). And, according to Peck (1964), the weakly welded ash-flow tuff that defines the base of member F is not a widespread unit. Thus, the correlation of this tuff in the Clarno area with the western facies type area is not tenable with these recent dates. l ower Big Basin Member claystones (unit Tjlb)-Widespread, thick, clayey. red beds in the lower part of the John Day Formation in the Clarno Unit are mapped as lower Big Basin Member, based on lithologic and stratigraphic similarities with the type section of this member in the Big Basin area of Picture Gorge. Recently recognized subdivisions of this member in a reference section from the Painted Hills area (Bestland and others, 1996, 1997; Bestland and Retallack, 1994b) are also recognized in the Clarno Unit.

OREGON GEOLOGY, VOLUME 61 , NUMBER I, JAHUARYIFEBRUARY 1999 13 MARINE NON-MARINE OXYGEN ISOTOPES STRATIGRAPHY

Painted Hills 28.7 28.8 lower Turtle Cove 29.8 Member w ~ ii5 u upper Big Basin o Mamber t:) '2 :::; ~ 32.7 middle Big Basin o 33.0 Member

"'11--1 '3 r-~---"

rower Big Basin Member

(,/arno IIttlB 38.2. w ii5 u 39.7 member A tuff :;""mammal qU8,ry- ow ~ ( upper "Red Hill" f' claystone. 42.7

Figure 9. Correlation of nonmarine stratigraphy from central Oregon with marine oxygen isotopic record, using the geomagnetic time scale of Cande and Kent (1992, 1995) as modjfied by Berggren and others (1992, 1995) and ,oAr/nAt radioisotopic age determinations from tuffs interbedded with paleosols. From Bestland and others, 1997.

The Eocene-Oligocene boundary is placed at 34 Ma (Swisher and Prothero 1990; Berggren and others, 1995). Marine isotopic data are from benthic foraminifera and are smoothed by linear interpolation (Miller and others, 1987). Oi1 and Oi2 are oceanic oxygen isotope cooling events (Miller and others, 1991 ).

The first major change in paleosol type occurs between the lower and upper red claystones of the Clarno Formation and corresponds with the chron 19 plate-tectonic reorganization (McGowran 1989). The dramatic change in paleosol type and the large truncation surface between the lower and middle Big Basin Members support the placement of the Eocene­ Oligocene boundary at approximately 34 Ma according to .oAr/9Ar age determinations from the central Oregon section. An early Oligocene climatic recovery is indicated by the presence of well-developed, clayey paleosols at the top of the middle Big Basin Member approximately dated at 32.0 to 32.7 Ma. A third major change in paleosol type between the upper Big Basin Member and lower Turtle Cove Member, at approximately 30 Ma, is synchronous with the Oi2 oceanic oxygen isotope cooling event.

14 OREGON GEOLOGY, VOLUME 61 , NUMBER I, JANUARY/FEBRUARY 1999 Middle and upper Big Basin M em­ Beds, brown, calcareous paleosols units are significant iri the context of bers (unit Tjmb) overlie these conglomerates and un­ correlating the Turtle Cove Member of The middle and upper Big Basin derlie the lacustrine and carbona­ the John Day Formation with the west­ Members were not delineated in the ceous shales of the Slanting leaf ern facies of the John Day Formation. Clarno area as they have been in the Beds. These conglomerates fill an Member G ash-flow tuff and re­ Painted Hills area (Bestland and Retal­ incised surface cut into underlying lated units are extensively exposed in lack, 1994b). In the Clarno area, red­ claystones of the lower Big Basin the western facies (Robinson, 1975) brown silty claystones, tuffs, and la­ Member and represent a major and in the Clarno area along the Iron custrine shales with leaf impressions, truncation surface, similar to a trun­ Mountain escarpment. This sanidine­ similar to the middle Big Basin mem­ cation surface identified in the rich tuff has been correlated with a ber in the Painted Hills, occur above Painted Hills area (Bestland and Re­ sanidine tuff in the Painted Hills area clayey red beds (lower Big Basin tallack, 1994b). This truncation sur­ (Hay, 1963; Woodburne and Robin­ Member) and below green tuffaceous face approximates the Eocene­ son, 1977) which has been recently strata with sanidine tuff. A sanidine Oligocene boundary. dated at 29.8 ± 0.02 Ma (Bestland tuff occurs in the lower part of the Member F basalts (unit Tjfb)­ and others, 1997). Turtle Cove Member in the Painted Al kaline olivine basalts of member F The ash-flow tuff sheet of member Hills (see Figure 9), where it was of the John Day formation H is also widespread in the western dated at 29 .8 Ma. Additionally, the (Robinson, 1969) occur extensively facies (Peck, 1964; Robinson, 1975) 33 .6 Ma age determinations from the in the Clarno area . Below Iron as well as in the eastern facies (Fisher, Slanting leaf Beds and the weIJ­ Mountain, John Day Formation 1966), where it is referred to as the documented Bridge Creek flora basalts of member F are in contact "Picture Gorge ignimbrite. " Member (Manchester and Meyer, 1987; with Columbia River Basalt Group. H has been correlated with the Pic­ Meyer and Manchester, 1997) from lava flows of this unit are also in ­ ture Gorge ignimbrite on the basis of these strata allow correlation of this terbedded with tuffaceous deposits lithology and stratigraphic position package with the middle Big Basin and paleosols of the middle and (Robinson and others, 1990). Two re­ Member. In the Painted Hills area, age upper Big Basin Members. The cent age determinations of this unit in determinations of 33 .0 Ma and 32 .7 stratigraphically lowest alkaline the Painted Hills are both 28.7 ± 0.07 Ma on tuff beds (Bestland and others, basalt is less than 10m above the Ma (Bestland and others, 1997). This 1997) are associated with the type Slanting leaf Beds. tuff is crystal poor and contains vari­ locality of the Bridge Creek flora able amounts of lithic fragments of (Chaney 1924, 1948) and are con­ Turtle Cove Member rhyolite and tuff. In the Clarno area, tained within the middle Big Basin Tuffs and tuffaceous siltstones two cooling units are present in the Member. Red, silty claystones strati­ and claystones of the Turtle Cove tuff, as has been recognized in the graphically above the Slanting leaf Member are recognized in the eastern facies by Fisher (1966). To the Beds and below a cliff-forming chan­ Clarno Unit on the basis of correla­ west of Clarno, closer to the source, nel complex (Figure Be) are similar to tion of tuffs in the western facies only one cooling unit is recognized Ticam and Skwiskwi pedotypes iden­ with this member in the eastern (Robinson and others, 1990). tified in the middle and upper Big facies (Woodburne and Robinson, Member I tuff in the Clarno area Basin Members from the Painted HiJJs 1977). The Turtle Cove Member as consists of a distinctive coarse-grained (see Bestland and others, 1997, for well as the ash-flow tuffs of mem ­ ash-flow sheet that occurs in scat­ pedotypes) , bers G, H, and I are exposed in The tered exposures high on the slopes of At the base of the middle Big Basin Cove , on the west side of Iron Iron Mountain. The tuff is up to 15 to Member and locally present in the Mountain above the John Day River, 20 m thick and contains coarse pum­ Clarno area , are conglomerates con­ and have been mapped previously ice fragments, coarse vitric shards, taining weathered clasts of tuff and by Robinson (1975) and by Bestland, and obsidian fragments. igneous flow rocks (Figure 2) . In gul­ BlackweJJ , and Kays (unpublished lies to the west of the Slanting leaf mapping 1986 and 1988). These tuff

SEDIMENTATION , VOLCANISM, AND PAST CLIMATE CHANGE

Clarno Formation deposi tional grained , alluvial paleosol or over­ flanked stratovolcanoes, possibly in setting bank deposits . White and Robinson fault-bounded minibasins in a ten ­ The Clarno Formation sed imentary (1992) interpret the coarse -grained sional arc setting-similar to the Qua­ units in this area can be broadly Clarno Formation deposits as proxi ­ ternary High Cascade graben of the grouped into coarse-grained debris­ mal, nonmarine lahar aprons and central Oregon Cascades (Smith and flow-dominated deposits and fine- reworked fluvial deposits that others, 1987; Taylor, 1990). Fine-

OREGON GEOLOGY, VOLUME 61 , NUMBER I, JANUARY/FEBRUARY 1999 IS grained overbank deposits and pale­ stack of red Luca paleosols with few John Day and Clarno Formations are osols are common in the formation, gleyed intervals. A large channel-fill now thought to be dominated by however due to the poor exposure of conglomerate is interbedded with paleosol horizons (Retallack, 1981, these claystone units, their distribu­ the claystones of Red HiJI at The 1991 a,b; Bestland and others, 1994, tion and sedimentology has been Gable (Bestland and Retallack, 1996, 1997; Bestland, 1997). Fur· largely ignored (Robinson, 1975; 1994a), which indicates that large thermore, most of the paleosols and Swanson, 1969) except in a few channels did exist on the alluvial their associated, although pedogeni­ places such as Red Hill (Retallack, plain. cally modified, substrates are inter­ 1981; 1991 a) and in the Cherry Creek Thick accumulations of alluvial preted as alluvial, and in a few cases area where White and Robinson paleosols occur in scattered pockets colluvial. deposits. Most of the pale­ (1992) briefly describe a thick section elsewhere in the Clarno Formation. osols in the John Day and Clarno of clayey red beds. Their distribution is not widespread, Formations are interpreted as flood­ Depositional setting of fossil probably due to rapid aggradation plain paleosols, based on the follow· sites in conglomerate of Hancock of coarse-grained units followed by ing general considerations: They are Canyon-Conglomerates of Hancock incision during volcanic quiescence. relatively laterally continuous and Canyon have a mix of debris-flow Only occasionally did alluvial plains show evidence of both well- and deposits, fluvial conglomerates, and exist for a sufficient length of time poorly drained conditions. They lack tuff beds. Compared to the conglom­ for the accumulation of finer grained coarse·grained channel bodies, which erate of the Palisades, the conglomer· alluvium. Red Hill sits stratigraphi­ indicates the predominance of vertical ate of Hancock Canyon, with its cally near the top of the Clarno floodplain accretion. Many different abundance of flood-surge or hyper­ Formation and probably marks the paleosol horizons have been identi­ concentrated deposits and fluvial re­ end of explosive andesitic volcanism fied and interpreted, and these pale­ worked beds, indicates a lower gradi­ in this part of the Clarno arc. osols can be broadly grouped into ent or more distal depositional setting. floodplain setting (alluvial) and hills· Within the Clarno area are numer­ John Day Formation depositional lope setting (colluvial) soil·forming en· ous fossil plant localities (including setting vironments. Landscape aggradation in several new sites, see Bestland and The John Day Formation repre­ the form of floods, pyroclastic air fall, Retallack, 1994a) that indicate appar­ sents a nonmarine back·arc basin wind-blown dust and ash, and colluvial ently dissimilar climates. The classic that received mostly pyroclastic de­ movement from upslope locations Nut Beds site yields plant fossils tritus from Cascade sources to the caused vertical accretion of soil hori­ strongly indicative of a tropical to west. The formation becomes finer zons. Larger scale additions of alluvium paratropical climate (Manchester, grained from west to east, following and colluvium periodically buried the 1981, 1994). In contrast, at the same the dispersal pattern of pyroclastic landscape and caused new soils to form stratigraphic level and in a similar material (Fisher, 1966; Robinson and on these deposits. Aggradational peri­ debris-flow depositional environment. others, 1984). The ash-flow tuffs of ods were interspersed with episodes of some fossil plants found in Hancock the John Day Formation contain downcutting, during which the alluvial Canyon suggest temperate condi­ sanidine and quartz and are rhyolitic and colluvial basin fill would be partially tions. It is likely that the Nut Beds (Robinson and others, 1990). Addi· removed (Bestland and others, 1997). flora represents a lowland, floodplain tionally, geochemical analyses of tuff rain forest, like the selva of tropical beds (Hay, 1962, 1963; Fisher, 1966) Eocene-Oligocene transition Mexico, whereas the Hancock Tree and C horizons of paleosols (Fisher, The long stratigraphic sequence of flora represents an early successional 1966; Getahun and Retallack, 1991 ; paleosols in the upper Clarno and forest located on an unstable braid Bestland and Retallack, 1994a,b) in· lower John Day Formations record a plain. The flora has similarities to dicate a rhyolitic to rhyodacitic com· dramatic paleoclimatic change. This is higher altitude forest with affinities to position for the tuffs and tuffaceous the transition from the Eocene to the cooler climate, like the Liquidambar alluvial deposits. The western facies Oligocene, when the Earth's climate oak forests of Mexico (G6mez· ash-flow tuff sheets thicken toward and biota changed from the warm, Pompa, 1973). the Warm Springs and Mutton mostly subtropical world of the Paleosols and ove rbank de­ Mountain areas. Taken together, Mesozoic and early Cenozoic to the posits-An overbank to piedmont al­ these facts support an interpretation glaciated world of today, or from the luvial setting is interpreted for the Red of a rhyolitic source for the John Day "hot house" to the "cold house" Hill claystones, based on laterally con­ Formation that was separate from (Prothero, 1994). These climatic and tinuous paleosol horizons present in the Western Cascades. biotic changes are centered around Red Hill and channel conglomerates Alluvial paleosols-The thick, the Eocene-Oligocene boundary, with interbedded with the claystones. The colorful claystone and tuff se· the changes appearing to be stepwise upper Red Hill section contains a thick quences so well known from the over several million years on either

16 OREGON GEOLOGY, VOLUME 61 , NUMBER I, JANUARY/F EBRUARY 1999 side of this boundary (Wolfe. 1978; ers, 1997). The change from Ultisol­ with the Oligocene Bridge Creek flora Miller and others. 1987, 1991; Retal ­ to Alfisol-like Luca paleosols is inter­ of the Slanting leaf Beds (temperate lack. 1992; Bestland and others. 1997). preted to be the result of climatic forest) and middle Big Basin Member Recen t work on the timing and cooling and drying during the late tuffaceous, Inceptiso!-like paleosols. global correlation of the Eocene­ Eocene (Figure 9). Changing paterns Oligocene boundary (Swisher and of oceanic circulation and volcanism ACKNOWLEDGMENTS Prothero, 1990; Prothero and are hypothesized to have caused a This report represents the com­ Swisher, 1992; Can de and Kent, late Eocene climate change at about bined efforts of EA Bestland and G.J. 1992) allows for a comparison of the 42 Ma (McGowran, 1989). The hia­ Retallack under contract with the Na­ stratigraphy and age determinations tus in volcanism recorded in the Red tional Park Service (Bestland and Re­ from the central Oregon stratigraphy Hill section from 44 Ma to about 40 tallack, 1994a,b), the University of with the global data base of climate Ma. when John Day or Cascade vol­ Oregon Geology Field Camp and its change (Bestland. 1997; Bestland and canism began. was a period of spo­ director, M . Allan Kays, and Portland others, 1997). Many of the existing radic volcanism transitional from the State University Geologic Field Meth­ global climate change data come Clarno to the Cascade arc. Following ods directed by RE. Hammond. Dis­ from deep-sea sediments and their this volcanic hiatus of approximately cussion with T. Fremd, 1. Jones, E. oxygen and carbon isotopic record 2-4 million years, renewed volcan­ Taylor, R. Goodfellow, and A. Min­ (Figure 9). In the John Day Formation, ism, represented by the andesite of dzenty have added to our under­ climatic steps centered around the Horse Mountain (unit Tcau), rejuve­ standing of the geology and paleon­ Eocene-Oligocene boundary corre­ nated the alluvial system with fresh tology of this area. R.A. Duncan of spond with member boundaries andesitic material and caused the the College of Oceanic and Atmo­ (Figure 9). Most notable is the deposition of the Hancock Mammal spheric Sciences, Oregon State Uni­ abruptness of the Eocene-Oligocene Quarry beds. These paleosols are versity, kindly supplied age determi­ climatic transition. The short time too weakly developed to interpret nations for a number of samples , span of this change is not apparent much in the way of paleoclimate, from paleontological evidence of ver­ except that it was relatively humid. REFERENCES CITED tebrates and plant fossils in the Pacific With the onset of John Day vol­ Berggren, W.A.. Kent. O.v., Obradovich. J,O .. and Swisher, CC, III, 1992, Toward are· Northwest because of the incom­ canism, the alluvial material changed vised Paleogene geochronology, in Prothero, pleteness of the fossil record. The from andesitic detritus to fine­ O.R., and Berggren, W.A., eds., Eocene· paleoclimatic record from paleosols in grained rhyodacitic ash . In the lower Oligocene climatic and biotic evolution: Princeton, N.J ., Princeton University Press, the Clarno and John Day Formations, Big Basin Member of the Clarno Unit p. 29-45. in contrast. is much more complete. area, strata contain strongly devel­ Berggren, WA, Kent, O.v., Swisher, ce., III, oped Alfisol- and Ultisol·like pale­ and Aubry, M. P., 1995, A revised CenozoIc geochronology and chronostratigraphy. in Paleoclimate and depositional osols. The geochemical composition summary Berggren. WA, Kent. OV. Aubry, M,P', and of these lower John Day paleosols is Hardenbol, J., eds., Geochronology, time A dramatic change in depositional much the same as that of upper scales and global stratigraphic correlation: Society of Economic Paleontologists and setting from an active volcaniclastic Clarno paleosols and indicates little, Mineralogists Special Publication 54, p. apron of the conglomerates of Han­ if any, climatic change from late 129-212. cock Canyon to the quiet floodplain Clarno time to early John Day time. Beslland. EA,1997, Alluvial terraces and pal~· osols as indicators of early Oligoc~ne eli· represented by the claystones of Red Not until approximately 34 Ma. at mat~ change (John Day Formation, Or~ ­ Hill records the the cessation of proxi­ the Eocene-Oligocene boundary, did gon): Journal of Sedimentary Re~arch, v. mal volcanic activity in at least this the climate change dramatically 67, p, 840--855. Bestland, EA. and Retallack. G.J .. 1994a, Geol­ part of the Clarno area. In the lower (Figure 9). In the Clarno area, this ogy and paleoenvironments of the Clarno part of Red Hili. strongly developed. boundary is marked by the contact Unit. John Day Fossil Beds National Monu· Ultisol-like paleosols dominate the between the lower and middle Big ment: National Park Service Open.File Re· port, 160 p. strata and represent long periods of Basin Member to the middle Big --1994b, Geology and paleoenvironments soil formation in a humid subtropical Basin Members. Paleosols formed af­ of the Painted Hills Unit. John Day Fossil climate. These paleosols are the most ter this transition are higher in base Beds National Monument: National Park Service Open-File Report. 211 p, weathered paleosols in the upper cations and lower in Fe and Ti than Bestland, EA, Retallack, G.J ., and Fremd, 1, Clarno and lower John Day Forma­ late Eocene paleosols. The climate 1994, Sequence stratigraphy of the Eocene· tions. In the upper part of Red Hill. change from subtropical to temper­ Oligocene transition : EKamples from the nonmarine volcanically influenced John Day strongly developed Alfisol·like pale­ ate conditions across this boundary basin: GeologICal Society of America, Field osols dominate the section and repre­ is contrasted dramatically by a com­ Trip GUldeboolc of the Annual Meeting, p. sent shorter periods of soil formation parison of the Eocene Nut Beds flora lAt-1AI9. --1995, Geology of the late Eocene Clarno in a similar but probably drier humid (tropical to subtropical forest) and Unit. John Day Fossil Beds National Monu­ subtropical climate (Bestland and oth- Red Hill clayey, Ultisol-like paleosols ment. central Oregon, inSantucci, VL., and

OREGON GEOLOGY, VOLUME 61 , NUMBER I, JANUARYlfE8RUARY 1999 11 McClelland, l., eds., National Park Service America Abstracts with Programs, v. 5, no. 1991 , Unlocking the ice house: Oligocene­ Paleontological Research: National Park Ser­ 1, p. SO. Miocene oxygen isotopes, eustasy, and vice, Technical Report NPS/NRPO/NRTR- ---1989, li!/~taC/!raS radlns/I'yi, a new margin erosion: Journal of Geophysical Re­ 95/16. p. 66-72. primitive rhinocerotid from the late search, v. 96. p. 6829-6848. 8estland, EA, Retallack, GJ., Rice, A .. and Eocene Clarno Formation of Oregon, in Nemec, w. , and Muszynski, A., 1982, Volcani­ Mindzenty, A., 1996, late Eocene detrital Prothero, D.R.. and Schoch, R.M .. eds .. clastic alluvial aprons in the Tertiary of Sofia laterites in central Oregon: Mass balan-ce The evolution of perissodactyls: New York. district (Bulgaria): Annals of the Geological geochemistry. depositional setting and land­ Oxford Unive~ity Press, p. 235-256. Society of Poland, v. 52, p. 239-303. scape evolution: Geological Society of ---1995, Stratigraphy and vertebrate fau· Noblett. J.B., 1981 , Subduction-related origin America Bulletin, v. 108, p. 285-302. nas of the Bridgerian·Duchesnean Clarno of the volcanic rocks of the Eocene Clarno 8estland, E.A., Retallack, GJ., and Swisher, Formation, north-central Oregon, in formation near Cherry Creek, Oregon: Ore­ C.C.,IIl, 1997, Stepwise climate change Prothero, D.R, and Emry, R.J ., eds ., The gon Geology, v. 43, p. 91-99. recorded in Eocene-Oligocene paleosol se­ Terrestrial Eocene-Oligocene transition in North American Commission on Stratigraphic quences from central Oregon: Joornal of North America : Cambridge, Cambridge Nomenclature. 1983. North American strati­ Geology. v. 105. p. 153-172. Unive~ity Press , p. 206-239. graphic code: AAPG Bulletin, v. 67, no. 5. p. Cande. S.c., and Kent. O.V. , 1992, A new Hay, R.l., 1962, Origin and diagenetic alter­ 841-875. geomagnetic polarity time scale for the late ation of the lower part of the John Day Peck, D.l., 1961 , John Day Formation near Cretaceous and Cenozoic: Journal of Geo­ Formation near Mitchell. Oregon. in En ­ Ashwood. north-central Oregon. chap. 343 physical Research, v. 97, p. 13.917-13,951 . gel. A.EJ .. James, H.l., and Leonard, B.F.. ofGeological Survey research . Short papers ---1995. Revised calibration of the geo­ eds .• Petrologic studies: A volume in honor in the geologic and hydrologiC sciences: U.S. magnetic polarity timescale for the late of A.F. Buddington : Geological Society of Geological Survey Bulletin 424-0, p. 153- Cretaceous and Cenozoic: Journal of Geo­ America, Buddington volume, p. 191-216. 156. physical Research. v. 100. p. 6093-6095. Hay. R.l., 1963, Stratigraphy and zeolitic dia­ Peck, D.L., 1964, Geologic reconnaissance of Chaney. R.W .. 1924. Quantitative studies of the genesis of the John Day Formation of Ore­ the Antelope-Ashwood area, north·central Bridge Creek flora : American Journal of Sci· gon: University of California Publications, Oregon, with emphasis on the John Day ence, v. 8, p. 127-144. Geological Sciences, v. 42, p. 199-261 . formation of late Oligocene and early ---1948. The an-cient forests of Oregon: Hotz. P.E ., lanphere, M .A .. and Swanson. Miocene age: U.S. Geological Survey Bul­ Eugene, Oreg.. Oregon System of Higher DA, 1977. Triassic blueschist from north­ letin 11610, 26 p. Education, Condon Lectures, 56 p. ern California and north-central Oregon : Pratt, J.A., 1988, Paleoenvironment of the Enlows, H.E.. and Parker, OJ., 1972, Geochro­ Geology, v. 5, p. 659-663. Eocene/Oligocene Hancock Mammal nology of the Clarno igneous activity in the Manchester. S.R., 1981, fossil plants of the Quarry of the upper Clarno Formation. Ore­ Mitchell quadrangle. Wheeler County, Ore­ Eocene Clarno nut beds: Oregon Geology. gon: Eugene, Oreg., University of Oregon gon: Oregon Department of Geology and v. 43, p. 75-81 . master's thesis, 104 p. Mineral Industries, Ore Bin, v. 34, p. 104-110. ---1990, Eocene to Oligocene floristic Prothero, D.R, 1994, The Eocene -Oligocene Evernden, J.f., and James, G.T. , 1964, Potas­ changes recorded in the Clarno and John transition : Paradise lost: New York, sium-argon dates of the Tertiary floras of Day formations, Oregon, U.S_A _, In Columbia Unive~ity Press (Critical moments North America: American Journal of Sci· Knobloch, E., and Kvacek, Z., eds., Pale­ in paleobiology and Earth history series), ence, v. 262, p. 945-974. ofloristic and paleoclimatic change in the 291 p. Evernden, J.F., Savage, D.E, Curtis, G.H., and Cretaceous and Tertiary, symposium pro­ Prothero. 0 .$1, .. and Swisher, c.c.. III, 1992, James, G.T., 1%4, Potassium-argon dates ceedings: Prague, Czekoslovakian Geolog­ Magnetostratigraphy an d geochronology of and the Tertiary faunas of North America: ical Survey Press, p. 183-187. the terrestrial Eocene-Oligocene transition American Journal of Science, v. 262, p. ---1994, Fruits and seeds of the middle in North America. In Prothero. D.R.. and 145-19B. Eocene Nut Beds flora. Clarno Formation. Berggren, W.A .. eds., Eocene- Oligocene cli­ Fiebelkorn, R.B., Walker. G.W., Macleod, N.S.. Oregon : Palaeontographica Americana, matic and biotic evolution : Princeton. N.J., McKee, E.H., Smith, J.G., 1982, Index to no_58, 205 p., 70 pl. Princeton University Press, p. 46-73. K-Ar age determinations for the State of Manchester, S.R, and Meyer. H.W.. 1987, Retallack. G.J .. 1981. Preliminary observations Oregon: U.S. Geological Survey Open-File Oligocene fossil planb of the John Day on fossil soils in the Clarno FormatIon Report 82-596, 40 p./I 1983, Isochronl Formation, fossil, Oregon: Oregon Geol· (Eocene to early Oligocene) near Clarno, West, no, 37, p. 3-60. ogy, v. 49. no. 10, p.II5-127. Oregon : Oregon Geology, v. 43, no. 11, fisher, R.V. 1966, Geology of a Miocene ign­ McGowran, B., 1989, Silica burp in the p.147-150. imbrite layer, John Day formation, eastern Eocene ocean: Geology, v. 17, p. 857-860. --1991a, A field guide to mid-Tertiary pa­ Oregon : University of California Publica · McKee, T.M ., 1970, Preliminary report on leosols and paleoclimatic changes in the bons. Geological ScIences, v. 67, 59 p. fossil fruits and seeds from the mammal high desert of central Oregon-Part 1: Ore­ Fisher, R.V., and Rensberger, J.M ., 1972, Physi. quarry of the Clarno Formation, Oregon : gon Geology, v. 53, no. 3, p. 51-59. cal stratigraphy of the John Day formation, Oregon Department of Geology and Mineral --1991 b, A field guide to mid-Tertiary pa­ central Oregon: University of California Publi­ Industries, Ore Bin. v. 32. p.117-132. leosols and paleoclimatic changes in the cations. Geological SCiences. v.101. p. I-45. Merriam. J.C .. 1901 a. A geological section high desert of cen tral Oregon-Part 2: Ore­ fisk, L.H .. and Fritts. S.G .. 1987. Field guide and through the John Day 8asin: Journal of gon Geology, v. 53, no. 4, p. 75-80. road log to the geology and petroleum po. Geology, v. 9, p. 71-72. ---1992, Paleosols and changes in climate tential of cenllal Oregon: Northwest Geol · Merriam, J.c., 1901 b, A contribution to the and vegetation across the Eocene­ ogy, v.16, p. 105-125. geology of the John Day basin: University Oligocene boundary, in Prothero, D.R.. and Gelahun, A. , and Retallack, GJ .. 1991. Early of California Publications. Bulletin of the Berggren, W.A .. eds .. Eocene-Oligocene cli­ Oligocene paleoenvironment of a paleosol Department of Geology. v. 2, p. 269-314. matic and biotic evolution: Princeton. NJ., from the lower part of the John Day Forma­ Meyer. H.W .. and Manchester, S.R. 1997. The Princeton Unlve~ity Press. p. 383-398. tion near Clarno. Oregon: Oregon Geology Oligocene Bridge Creek flora of the John Retallack, G.' .. Bestland. EA, and Fremd, 1. v. 53, p. 131-136. Day Formation, Oregon: University of 1996. Reconstructions of Eocene and G6mez-Pompa. A .. 1973. Ecology of the vege­ California Publications. Geological Sci­ Oligocene plants and animals of central tation of Veracruz. InGraham. A., ed .. Veg­ ences, v. 141 , 195 p .. 75 plates. Oregon : Oregon Geology. v. 58, p. 51-69. etation and vegetational histOfy of northern Miller. K.G., Fairbanks. R.G., and Mountain. Robinson, p.T., 1969, High-titania alkali-olivine latin America : Amsterdam, ElseVier, p. 73- G.S.• 1987, Tertiary oxygen isotope syn­ basalt of north-central Oregon, U.S.A: Con­ 148. thesis, sea level histOfy, and continental tributions to M ineralogy and Petrology, v. Hanson, C.B., 1973, Geology and vertebrate margin eroslOfl: Paleoceanography, v. 2, p. 22, p. 349-360. faunas in the type area of the Clarno forma­ 1-19. ---1975, Reconnaissan-ce geologIC map of tion, Oregon [abs.]: Geological Society of Miller, K.G., Wright, J . ~ ., and Fairbanks, RG., the John Day Formation in the southwestern

I. OREGON GEOLOGY, VOLUME 61 , NUMBER I, JANUARY/FEBRUARY 1999 part of the Blue Mountains and adjacent Bulletin, v. 97, p. l-10. --1990, Volcanic history and tectonic de ­ areas, north-central Oregon: US Geologi­ Smith, G.A., Conrey, R.M ., and Mcintosh, velopment of the central High Cascade cal Survey Miscellaneous Geologic Investi­ We., 1996, Eo·Oligocene stratigraphy Range, Oregon: Journal of Geophysical Re ­ gations Map 1-872, 1 :125,000. and structure, Gray Butte area, central search, v 95, no. B12, p. 19,611-19,622. Robinson, P.T., and Brem, G.F., 1981, Guide to Oregon: Faulting and volcanism along the Vance, J.A., 1988, New fission track and K-Ar geologic field trip between Kimberly and Blue Mountain lineament fabs.l : Geologi­ ages from the Clarno Formation, Challis·age Bend. Oregon with emphasis on the John cal Society of America Abstracts with Pro ­ volcanic rocks in north-central Oregon Day Formation, in Johnston, D.A.. and grams, v. 28, no. 5, p. 112-113. 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Swanson, D.A. , 1969, Reconnaissance geo· 1951, Quicksilver deposits of the Horse Rogers, J.w, and Novitsky·Evans, J.M., 1977, logic map of the east hall of the Bend Heaven mining district. Oregon : US Geo­ The Clarno Formation of central Oregon, quadrangle, Crook, Wheeler, Jefferson, logical Survey Bulletin 696-E, p. 105-149 U.S.A.: Volcanism on a thin continental Wasco, and Deschutes Counties: U.s. Ge · White, rD l., and Robinson, P.T., 1992, Intra­ margin : Earth and Planetary Science Letters, ological Survey Miscellaneous Geological arc sedimentation in a low·lying marginal v.34, p. 56-66. Investigations Map 1-568, 1 :250,000. are, Eocene Clarno Formation, central Ore­ Rogers, J.w., and Ragland, P.e., 1980, Trace Swanson, O.A .. and Robinson, P.T.,1968, Base gon: Sedimentary Geology, v. 80, p. B9- elements in continental-margin magma­ of the John Day Formation in and near the 114. tism-Part 1. Trace elements in the Clarno Horse Heaven mining district, north­ Wolfe, J.A. , 1978, A paleobotanical interpreta ­ Formation of central Oregon and the nature cen tral Oregon, in U.S. Geological Survey tion of Tertiary climates in the northern of the continental margin on which eruption research, chapter 0 : u.s. Geological Sur­ hemisphere: American Scientist, v. 66, p occurred: Geological Society of America vey Professional Paper 600-0, p. 0154- 694- 703. 8ulletin, v. 91, p. 563-567. 0161 Woodburne, M .O ., and Robinson, P. T., 1977, A Scott. K.M .. 1988, Origins, behavior, and sedi· Swisher, e.e., III, and Prothero, O.R .• 1990, new late Hemingfordian mammal fauna mentology of lahars and lahar·runout flows Single crystal ooAr/ l9Ar dating of the from the John Day Formation, Oregon, and in the Toutle·Cowlitz River system: U.S. Eocene ·O ligocene transition in North its stratigraphic implications : Journal of Pale · Geological Survey Professional Paper 1447- America: Science, v. 249, p. 760-762. ontology, v. 51, p. 750-757. 0 A, 74 p. Taylm, E.M., 1960, Geology of the Clarno Smith, G.A., 1986, Coarse-grained volcaniclas­ basin, Mitchell quadrangle, Oregon: Cor· tic sediment: Terminology and depositional vallis, Oreg., Oregon State University processes: Geological Society of America master's thesis, 173 p.

DOGAMI PUBLICATIONS be identified and thei r danger from Released December 11. 1998 flooding or their use as potential Geology of the Henkle Butte quad· evacuation routes assessed . Each rangle, Deschutes County, Oregon, Released July 22, 1998 potential tsunami flooding area is by E.M. Taylor. Geological Map Series Tsunami hazard map of the Seaside· outlined, as is the actual flooding GMS-95, scale 1 :24,000, 5 p. text, Gearhart area, Clatsop County, level of the 1964 tsunami that was $10. Oregon, by George R. Priest. Edward triggered by a great earthquake in A new geologic map of the Henkle Myers, Antonio Baptista, Robert Alaska and killed people as far away Butte quadrangle helps explain the Kamphaus, Brooke Fiedorowicz, Cu rt as Crescent City, California. geology of the eastern side of the D. Peterson, and Thomas S. Horning. Because of the potential loss of Cascade Range. The map includes Interpretive Map Series IMS-3, scale life and property from these events, part of the Deschutes National Forest. "'2,000, $6. many government agencies have A diverse mix of volcanic and sedi~ This map shows how three differ· contributed to this map and will mentary rock covers the area. Can· ent tsunamis might affect the area. continue to work with the commu· struction aggregrate has been mined Computers were used to simulate nities. The Oregon Graduate Insti· from the local cinder cones and grav· three different local earthquakes and tute of Science and Technology, els. Until about 1 ,6 million years ago, the tsunamis they might cause. These Portland State University, and the the landscape was mostly rim·rock simulations were used in conjunction National Oceanic and Atmospheric lava and a few river deposits. Since with field-based mapping and analyses Administration provided scientific then, the area has been eroded by of core samples to produce the map. research to produce the map. The streams that carved the Fremont, The map has an aerial photo as its State of Oregon and the City of McKenzie, and Deep Canyons (now base, so that streets and buildings can Seaside helped fund the project. (Conllnued on page 22)

OREGON GEOLOGY, VOLUME 61 , NUMBER I, JANUARY/F EBRUARY 1999 19 BOOK REVIEWS entries to help bring understanding Published by Confluence Press to geoscience words like asperity, (lewis-Clark State College), the 151 - Holocene, P wave, and shear wall. page volume is an entertaining and living with Earthquakes in the Pa­ An extensive bibliography suggests informative geologic expose, filled cific Northwest , by Robert S. Yeats. additional reading for those inter­ with pictures and maps and geologic Oregon State University Press. 101 ested. descriptions. The author, Tracy Vallier, Waldo Hall, Corvallis. Oregon 97331 . It is true that we cannot prevent has taken the time to explain complex 6407. o5u.orst.edu/ depV press, 1998. earthquakes, but it is also true that geologic terms . Dr. Vallier has also 309 p., ISBN 0·87071 ·437·6, soft we can learn to live with them and provided the reader an intimate look cover, $21 .95. (Available from to survive them. Are we ready for at his personal 30-year struggle in OOCAM! : See last page of this issue.J the next big one? Most experts say unravelling Hells Canyon's geologic Accurately forecasting the next we are not, but Yeats' book details a history. I strongly recommend that major earthquake in the Pacific number of measures one can put in anyone in terested in the geologic Northwest is an impossible task. The place to counter a destructive event. story of Hells Canyon take a look at notion that Mother Earth transmits Considerations for purchasing earth­ this book. It is an enjoyable read . reliable data for this kind of event quake insurance, readying the home -Mark L. Ferns isn't supportable by past measurable for shaking and shifting ground, and Oregon Department of Geology 3nd events. So what is the next best thing design implications for structures Mineral Industries, B3ker City Office to do to prepare for the upcoming large and small are all clearly de­ inevitable earthquake? tailed. Also, there is a discussion of Correction Answer: Read Living Wdh Earth­ the role of state and local govern­ Author Frank Hladkey has called quakes In The Pacific Northwest by ments in dealing with earthquakes. Dr. Robert S. Yeatsl Dr. Yeats has succeeded in com­ to our attention that an error slipped into Table 1 of his recent article Dr. Yeats' credentials are weJJ es­ municating vital information to his about Upper Table Rock and l ower tablished and revered through a quar­ readers. The public's next step is to Table Rock. In the July/ August 1998 ter century of earthquake study and pick up a copy and to read it. With issue (v. 60, no. 4), on page 85, in scientific analysis on inner earth rum­ recent reports of swarms of small the analyses for oxides, the numbers blings around the world. He is a se­ disturbances under Mount Hood for Na were reported incorrectly. nior consultant for Earth Consultants and frequent articles about the Cas­ 20 The correct values are listed below International and a professor emeritus cadia subduction zone, which lies a along with the respective sample in the geosciences department at few miles off Oregon's coastline, it Oregon State University. becomes increasingly important that numbers: Unlike many other earth science the general public become in­ Sample no. NalO authors, Yeats focused on a layman's formed. Reading this book is the interest in and background of scien­ right step in that direction. BAG·614 4.51 tific knowledge. Simply put, the book - Don Christensen BAG -615 4.52 is an easy read and down to earth. DOGAMI Governing Board Member BBG -202 4.59 Yeats' use of humor, graphs, and pho­ Depoe Bay, Oregon BBG -203 4.18 tographs makes this an informed and BBG -207 3.98 understandable writing. Islands and Rapids. A Geologic What can you expect to learn? For Story of Hells Canyon, by Tracy We apologize to our readers for one, inner-earth disturbances result Vallier. Confluence Press, lewiston, the oversight and are grateful to from strained rock . A detailed expla­ Idaho, 1998. 151 p., ISBN ,- Frank for catching it. 0 nation of this straining and its relation 881090-30-2, soft cover, $25. to te ctonic movement brings the [Available from DOGAMI: See last New fossil book at reader to an understanding of the page of this issue .] what. where, and why of earth­ Islands and RapIds is highly rec ­ Nature of the Northwest quakes. Also, shaky ground, land­ ommended reading for anyone Oregon Fossils, by Elizabeth and slides, and big sea waves are all possi­ planning a visit to the Hells Canyon William Orr. Kendall/ Hunt Publishing ble results of inner-earth distur­ country of eastern Oregon. Here at Company, Du buque, Iowa, 1999. bances . Readers will recognize the last is a comprehensive geologic 381 p., ISBN 0-7872-5454-1, soft locations of many recent earthquake guide to one of North America's cover, $40.95. events like Scotts Mills, Klamath Falls, scenic treasures, written by Dr. Tracy The book discusses Oregon's fos­ Oregon's Capitol Building, and Vallier, the man who has spent the sils in the context of their original Mount St . Helens. For the lay reader, most time and effort to decipher the environments and of the people who Yeats provides six pages of glossary geologic mysteries of Hells Canyon. discovered and studied them. 0

20 OREGON GEOLOGY, VOLUME 61, NUMBER I, JAN UARY/F EBRUARY 1999 Report on Colombia earthquake damage to lifelines by 'Yllmei Wang; Oregon Department ofGeology and Mineral Industries On January 25. 1999, a magnitude assessing the need and feasibility to threat to sever·water aqueduct, air· 5.9 earthquake occurred near the city dispatch a TCLEE investigation team port available only to relief efforts. of Armenia, Colombia. and so far to report on the lifeline damage. electricity interrupted. more than 400 aftershocks have been [Yumei Wang from DOGAMJ is one Cajamarca: landslides blocking registered. Current reports include of the possible team members.-ed.J roads: other transportation problems. over 700 confirmed deaths. over However, Edwards warns that Alcala: Only partial telephone ser· 180,000 homeless, and numerous Colombia is " considered one of the vice. landslides, road blockages. and survivors needing food, medical aid, most dangerous countries in the other transportation problems . and clothing. Conditions are made world for travel, even without the Ulloa: No communications. worse by civil unrest, particularly in effects of an earthquake." and such Caicedonia : Very difficult tele· the two major cities of Armenia and a team would put an additional bur· phone communications. hospital Pereira. and by continuing rainfall den on local authorities who are damaged. that acts as an additional cause for al ready stretched to the limits of Obando: Health center damaged. more landslides that have already af· their capabilities in the face of the Calarca: Hospital damaged, only fected most of the mountain roads. current situation of food shortages, extreme emergencies treated. aque· Structures and lifelines were con· looting and protesters, limited trash duct inlet destroyed, roads blocked. siderably damaged. Quantification of collection. and spreading diseases . Montenegro: No electricity, land· the damage and losses is practically Edwards provided the following slides. impossible, because among the local list of selected lifeline damage to C6rdoba: Hospital collapsed . authorities there is no uniform termi· towns shown on the map below; La Tebaida : Water and electricity nology and system of distinguishing Armenia (223,000 inhabitants, services interrupted. types of damage and loss . more than 500 fatalities. more than Pijao; Electrical service out. A preliminary lifeline damage sum· 57 percent of homes affected); Civil Quimbaya: Electrical service out. mary was compiled by Curt Edwards. unrest: no trash service : health More information can be obtained Chair of the Earthquake Investigation problems evident, and vaccinations (in Spanish only) from the website Committee of the American Society underway; no water, no electricity, pages of the Observatorio Sis· of Civil Engineers Technical Council aqueduct out, airport control tower mol6gico del SurOccidente (0.5.5.0 .) on Lifelines Earthquake Engineering out of service. at the following address: http:// (ASCE ·TClEE). Edwards is currently Pereira: Civil unrest, landslide osso.colombianet.net 0

Clirdob • • VAlLE .*

Above and left: location maps of western portion of Colombia . Rectangle indicates ap· proximate outline of detail map on lett. Star indicates earthquake epicenter. Sources : Ob· servatorio Sismol6gico del SurOccidente and l exikografisches Institut, MOnchen.

OREGON GEOLOGY, VOLUME 61 , NUMBER I, JANUARYIFEBRUARY 1999 21 (Continued from p.1ge 19) Released January 4. 1999 the ci ty, This area is important be­ dry) and by Squaw Creek. The broad, Earthquake damage and loss esti­ cause the sliding is regional and can ­ level plains now support residential mate for Oregon, by Yumei Wang . not be easily studied or controlled in and agricultural development. Open-File Report o-98-, $10. but recognizes that all levels of gov­ This is a pilot project with partici­ Released February 1,1999 ernment. businesses, community or­ pation by federal, state, and local Mist Gas Field map. 1999 edition. ganizations, households. and individ­ governments. The Salem Hilts are a Open-file Report 0-99-01 , map uals play roles in reducing a commu­ landslide-prone area with intensive scale 1 :24,(XX), production statisti~ for nity's vulnerability to earthquakes. development in the southern part of 1993-1998, $8. 0

AVAILABLE PUBLICATIONS OREGON DEPARTMENT OF GEOLOGY AND MINERAL INDUSTRIES

BULLETINS Price MISCEllANEOUS PAPERS Price 103 Bibliography (8 th supplement. 1980-84). 1987 8.00 20 Investigations of niCkel in Oregon. 1978 6.00 102 Bibliography (7th supplement. 1976-79). 1981 5.00 19 Geothermal e~ploration studies m Oregon, 1976. 1977 4.00 101 Geologic field trips, w. Olegon/SW Washington. 1980 ___10 .00 15 Quicksilver deposits in Oregon. 1971 4.00 99 Geologic hazards, NW Clackamas County. 1979 11.00 11 Articles on meteorites (reprin" from the Ore Birl). 1968 4.00 98 Geologic hazards, E. Benlon County. 1979 10.00 5 Oregon's gold placers. 1954 2.00 97 Bibliography (6th supplement. 1971-75). 1978 4.00 SHORT PAPERS 96 Magma genesIs. Chapman Cont. on Parlial Melting. 1977 __15 .00 27 Rock material resources of Benton County. 1978 5.00 95 North Amellcan ophiolites (IGCPprojectJ. 1977 B.OO 25 Petrography of Rattlesnake Formation at type area. 1976___ 400 94 land use geology, cen tral Jackson County. 1977 10.00 OIL AND GAS INVESTIGATIONS 93 Geology, min res, and rock matenal. Curry County. 1977 __800 19 Ort and gas potenhal. S. Tyee Basrn. 1996 20.00 92 FOSSils In Oregon. Repflnts from the Or~BliI.1977 5.00 18 Schematic fence diagram. S. Tyee BaSin. 1993 9.00 91 Geol. hazards, Hood River, Wasco. Sherman Co. 1977 900 17 CfOSS section, MISt Gas Field to contmental shelf. 1990 10.00 90 land use geology of western Curry County. 1976 10.00 16 Avail. well re

II OREGON GEOLOGY, VOLUME 61, NUMBER I, JANUARY/FEBRUARY 1999 AVAILABLE PUBLICATIONS OREGON DEPARTMENT OF GEOLOGY AND MINERAL INDUSTRIES (continue d )

GEO LOGICAL MAP SERI ES Pr ic e Price GM S- 113 f ly Valley 7'h' quad., Union County. 1998 10.00 GMS-46 Breitenbush River area, Unn and Marion Counties. 1987_7.00 GMS -110 Tucker Flat 7'1>' quad., Union/ Baker C. 1997 6.00 GMS-45 Madras WesVEast 7'h' quads., Jefferson County. 1987__ 5 .00 GMS -108 Rio Canyon 7'1>' quad., Jackson C. 199B 6,00 as set with GMS·43 and GMS-44 11 .00 GMS -106 Grizzly Peak 7'1>' quad., Jackson County. 1997 6,00 GM S·44 Seekseequa Junction/ Metolius Bench 7%' quads. 1987 __5 .00 GM S- 105 EO hazards, Salem EasVWest 7'1>' quads. 1996 12 .00 as se t with GMS·43 and GMS-45 11 .00 GMS- 104 EO hazards, Unnton 7'1>' quad. 1996 10.00 GM S·43 Eagle Butte/Gateway 7%' quads. 1987 5.00 GMS- 101 Stee/head Falls 7'1>' quad. 1996 7.00 as set with GMS-44 and GMS-45 11 .00 GMS -100 EO hazard maps for Oregon. 1996 B.OO GMS·42 Ocean floor off Oregon 6. adj. cont. margin . 1986 9,00 GMS·99 Tsunami hazard map, Siletz Bay, Lincoln C. 1996 6.00 GMS -41 Etkhorn Peak 7'h' quad" Baker County. 1987 7,00 GMS·9B Dora and Sitkum 7'h' quad.s, Coos County. 1995 6.00 GMS -40 Aeromagnetic anomaly maps, north Cascades. 1985__ 5 .00 GMS·97 Coos Bay 7'1>' quad., Coos County. 1995 6.00 GM S-39 Bibliogr. 6. index: Ocean floor, cont. margin. 1986 6,00 GM S·95 Hen kle Butte 7'11' quad., Deschutes County. 199B_10.00 GMS-38 NW V. Cave Junction 15' quad., Josephine County. 1986_7.00 GMS·94 Charleston 7'1>' quad., Coos County. 1995 B.OO GMS -37 Mineral resources, offshore Oregon. 1985 7,00 GMS·93 EO hazards, Siletz Bay area, Uncoln County. 1995__ 20 .00 GMS·36 Mineral resources of Oregon . 1984 9.00 GMS·92 EO hazards, Gladstone 7'1>' qu ad. 1995 10.00 GMS -35 SW V. Bates 15' quad., Grant County. 1984 6.00 GMS·91 EO hazards, Lake Oswego 7W quad. 1995 10.00 GMS -34 Stayton NE 7%' quad., Marion County. 1984 5.00 GMS -90 EO hazards, Beaverton 7W quad, 1995 10.00 GMS·33 Scotts Mills 7%' quad., Clackamas/Marion C. 1984 ___5 .00 GMS-89 EO hazards. Mt. Tabor 7'1>' quad, 1995 10.00 GMS·32 Wilhoit 7%' quad" Clackamas/ Marion Counties. 1984 __5 .00 GMS-88 Lakecreek 7'h' quad., Jackson Cou nty. 1995 8.00 GMS·31 NW ';" Bates 15' quad., Grant County. 1984 6.00 GMS-87 Three Creek Butte 7'1>' quad., Deschutes C. 1996 6.00 GMS·30 SE '!. Pearsoll Peak 15' qu., Curry/ Josephine C. 1984 ___7 .00 GMS-86 Tenmile 7'1>' quad., Douglas County, 1994 6.00 GMS·29 NE V. 8ates 15' quad., Baker/Grant Counties. 1983 6.00 GMS-85 Mount Gurney 7'1>' quad .. Dougtastcoos C. 1994 ___6 .00 GMS-28 Greenhorn 7'h' quad., Baker/Grant Counties. 1983___ 6 .00 GMS-84 Remote 7'1>' quad., Coos County, 1994 6.00 GMS-27 The Dalles 10 x? quadrangle. 1982 7.00 GMS -83 Kenyon Mountain 7'h' quad., Douglas/Coos C. 1994 __600 GMS·26 Residual gravity, north/ ctr./south Cascades. 1982 6.00 GM S·82 Limber Jim Creek 7'h' quad., Union County. 1994 ___500 GMS-25 Granite 7'1>' quad., Grant County. 1982 6.00 GMS -81 Tumalo Dam 7'h' quad., Deschutes County. 1994 6,00 GMS-24 Grand Ronde 7%' quad., Polk/Yamhill Counties. 1982 __6 .00 GMS -80 Mcleod 7W quad., Jackson County. 1993 5,00 GMS ·23 Sheridan 7W quad., Polk and Yamhill Counties. 1982 __6.00 GMS -79 EO hazards, Portland 7'11' quad, 1993 20.00 GMS·22 Mount Ireland 7%' quad., Baker/ Grant C. 1982 6.00 GMS -78 Mahogany Mountain 30xGO' quad" Malheur C. 1993_10.00 GMS·21 Vale East 7%' quad., Malheur County. 1982 6.00 GMS-J7 Vale 30xGO' quad., Malheur Cou nty, 1993 10.00 GMS-20 S'h Burns 15' quad" Harney County. 1982 6.00 GM S-76 Camas Valley 7'1>' quad., Doug/aS/Coos C. 1993 6.00 GMS·19 Bourne 7'h' quad., Baker County. 1982 6.00 GMS·75 Portland 7'h' quad. 1991 7.00 GMS -18 Rickreall, Salem w., Monmouth, Sidney 7'h' quads. 1981_6.00 GM S·74 Namorf 7'11' quad" Malhwr County. 1992 5.00 GMS -17 Aeromagnetic anomaly map, south Cascades. 1981 ___' .00 GMS·73 Cleveland Ridge 7'11' quad., Jackson County. 1993 ___5.00 GMS -16 Gravity anomaly maps. south Cascades. 1981 4.00 GM S·72 Little Valley 7'h' quad .. Malheur County. 1992 5.00 GMS-1S Gravity anomaly maps, north Cascades. 1981 4.00 GMS·71 Westfall 7W quad., Malheur County. 1992 5.00 GMS-14 Inde x to published geol. mapping, 1898-1979. 1981 __' .00 GMS·70 Boswell Mountain 7V1' quad., Jackson County. 1992 __7 .00 GMS-13 Huntington/ Olds ferry 15' quads., Baker/ Malheur C. 1979_4,00 GMS·69 Harper 7W quad., Malheur County. 1992 5.00 GMS -12 Oregon part, Mineral 15' quad., Baker County. 1978 __' .00 GMS -68 Reston 7W quad., Douglas County. 1990 6,00 GMS·10 Low- to intermediate-temp. thermal springs/wells. 1978_'.00 GMS -67 South Mountain 7W quad .. Malheur County. 1990__ 6 .00 GMS·9 Aeromagnetic anomaly map, central Cascades. 197B __' .00 GMS -66 Jonesboro 7'h' quad., Malheur County, 1992 6.00 GM S·8 Bouguer gravity anom. map, central Cascades. 197B __' .00 GMS-65 Mahogany Gap 7'h' quad., Malheur County. 1990___ 5 .00 GMS -6 Part of Snake River canyon. 1974 8.00 GM S-5 Powers 15' quadrangle, Coos and Curry C. 1971 4.00 GM S·64 Sheaville 7'h' quad .. Malheur County. 1990:i~===5 . 00 GM S·63 Vines Hi1l7 'h' quad., Malheur County. 1991 5.00 IN TE RPRETI VE MAP SER IES GM S·62 The Elbow 7'h' quad .. Malheur County. 1993 8.00 /MS·6 Water-induted landslide hazards, Salem Hills, 1998__ 1 0.00 GMS·61 Mitchell Butte 7V1' quad .. Malheur County. 1990 5.00 IMS.4 Geology/ faults/ sedim. th ickness, Oregon City quad, 1997_10.00 GMS·60 Damascus 7'h' quad .. Clackamas/Multnomah C. 1994_'00 IMS· 3 Tsunami hazard map, Seaside area. 199B 6.00 GMS·59 La ke Oswego 7V1' quad, 1989 7.00 IMS -2 Tsunami hazard map, Yaquina Bay area. 1997 6.00 GMS· 58 Double Mountain 7W quad., Malheur County_ 1989 __5.00 IMS· 1 Relative EO hazards, Portland metro area. 1997 12 .00 GMS· 57 Grassy Mountain 7W quad" Malheur County. 1989 __5 .00 MINEO LAND RECLAMATI ON PROG RAM STATUS MAPS Adrian 7'h' quad., Malheur County, 1989 5.00 GMS -56 MlR-03 Clackamas Counly. 1998 10.00 GMS·55 Owyhee Dam 7v,' quad., Malheur County. 1989 5.00 MlR-10 Douglas County. 1998 10.00 GMS·54 Graveyard Point 7'h' quad., Malheur/ Owyhee C. 1988_5.00 MLR-17 Josephine County. 1998 10.00 Owyhee Ridge 7v,' quad., Malheur County. 1988___ 5.00 GMS·53 MlR·24 Marion County. 1998 10.00 GM S·52 Shady Cove 7'1>' quad .. Jackson County. 1992 6.00 U,S. GE OLOGIC AL SURVEY MAPS PLOTTED ON DEM AND GMS -51 Elk Prairie 7'h' quad., Marion/Clackamas C. 1986___ 500 OFR 97·513 Volcano hazards at Newberry vokano 10.00 GMS -50 Drake Crossing 7V1' quad .. Marion County. 1986 5.00 OFR 97·089 Volcano hazards in the Mount Hood region 10.00 GMS -49 Map of Oregon seismicity, 1841·1986. 1987 4.00 OFR 94·021 Geologic map, Tillamook highlands {2 sheets) ___20 .00 GMS -48 McKenzie Bridge 15' quad., Lane County. 1988 9.00 GMS -47 Crescent Mountain area, Unn County. 1987 7.00 Allow two weeks fo r delivery on a ll ma ps plotted on demand.

OREGON GEOLOGY, VOLUME 61, NUMBER I, JANUARYiJE8RUARY 1999 13 OREGON GEOLOGY Periodicals postage paid at Portland, OR Suite 965, 800 NE Oregon Street # 28, Portland, OR 97232-2162

AVAILABLE OEPARTMENT PUBLICATIONS (continued) SPECIAL PAPERS Price MISCELLANEOUS PUBLICATIONS Price'

29 Earthquake damage and loss estimates for Oregon. 1999_ 10.00 'Oregon lossils.1999 40.95 28 Earthquakes Symposium Proceedings, AEG Meeting. 1997 __12.00 ' Living with earthquakes in the Pacific Northwest . 199B 21.95 27 Construction aggregate markets and forecast. 1995 15.00 'Islands &. Rapids. Geologic story of Hells Canyon. 1998 25.00 26 Cross section, N. Coast Range to continental slope. 1992 ___11,00 'The Pacific Northwest coast: Living with shores. 1998 18.50 25 Pumice in Oregon. 1992 9.00 'Hiking Oregon's geology. E.M. Bishop and J.E. Allen, 1996 ___16.95 24 Index to Forums on Industrial Minerals, 1965-1989.1990___ 7 .00 'Assessing EO ha~ards in the PNW (USGS Prof. Paper 1560) ___25.00 23 Forum on Industrial Minerals, 1989, Proceedings. 1990 10.00 ' Geology of Oregon, 4th ed. 1991 33.95 22 Silica in Oregon. 1990 8.00 'Geologic map of Oregon. 1991 1150 21 Geology, NWV. Broken Top 15' quad .. Deschutes Co. 1987__ 6.00 ' Geol. of the Pacific Northwest. 1996 45.00 20 Bentonite in Oregon. 1989 7.00 ' Geologic highway map (AAPG), PNW region. 1973 8.00 19 Limestone deposits in Oregon. 1989 9.00 ' landsat mosaic map (published by ERSAL, OSU). 1983 11.00 18 Investigations of talc in Oregon. 1988 8.00 Mist Gas Field map. 1999 (OFR 0-99-1) S.OO 17 8ibliography of Oregon paleontology, 1792-1983. 1984 7.00 Digital disk (CAD forma ts .DGN, .DWG, .DXF) __25.00 16 Inde~ to Ore 8in and Oregon GeoIogy(1939·82). 1983 5.00 Mist Gas Field production 1979-1992 (OFR 0-94-6) 5.00 15 Geology/geothermal resources, central Cascades. 1983 13.00 Oregon rocks and minerals, a description. 1985 (OFR 0-88-6) __6.00 14 Geology/geothermal resources. Mount Hood area. 1982 8.00 Mineral information by county (OFR 0·93-S), 2 diskettes 25.00 13 Faults and lineaments of sou thern Cascades, Oregon. 1981 __5.00 Directory of mineral producers. 1993 (OFR 0·93·9) 8.00 12 Geologic linears, N. part of Cascade Range, Oregon. 1980__ 4 .00 Geothermal resources of Oregon (OOGAMI/NOAA map}. 1982 __4 00 11 8ibliography/inde~. theses/dissertations, 1899·1982. 1982 __7.00 Mining claims (State laws on quartz and placer claims) Free 10 Tectonic rotation of the Oregon Western Cascades. 1980___ 4.00 Sack issues of Oregon Geology 3.00 9 Geology of the Brei tenbush Hot Springs quadrangle. 1980___ 5.00 • Non-Departmental publications require additional S3 for mailing. 8 Geology and geochemistry, Mount Hood volcano. 1980 4. 00 7 Pluvial Fort Rock lake, Lake County. 1979 5.00 Separate price lish for open-file reports, tour guides, recre­ 6 Geology of the La Grande area. 1980 6.00 5 Analysis and forecasts of demand for rock materials. 1979___ 400 ational gold mining information, and non.Departmental maps 4 Heat flow of Oregon. 1978 4. 00 and reports will be mailed upon request. 3 Rock material, Clackam./Columb./Multn.fWash. Co. 1978 8.00 The Department also sells Oregon topographic maps pub· '2 Field geology, SW Broken Top quadrangle. 1978 --5.00 lishe~ by the U.S. Geological Survey.

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24 OREGON GEOLOGY, VOLUME 61, NUMBER I, JANUARY/FEBRUARY 1999