DOCSLIB.ORG

Download PDF of the Book

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Download PDF of the Book A Beginner’s Fossil Guide to the Northern California Coast Unearthing Evidence of Creatures from Deep t i m e By Leslie Scopes Anderson acknowledgements: This book would not have been possible without the help of my advisor, Humboldt State University professor Dr. William Miller, who was an invaluable resource of knowl- edge, wisdom and guidance. He conceived the idea for this guide and was instrumental in its progress and completion. Also thanks to HSU graduate students Adam Jackson and Christa Jackson for their asssistance. About the Author: Leslie Scopes Anderson received a BFA Copyright © 2011 by Leslie Scopes Anderson, and Hum- from University of Utah and is now a graduate student at boldt State University, Arcata, CA. Humboldt State University. She is a nature photographer All rights reserved. and a volunteer naturalist at the Arcata Marsh. She has an avid interest in and curiosity about Copies may be printed for indiviual or class use but may our natural world. Please contact her not be sold or distributed for profit without witten permis- with any comments or corrections sion from the author. about this guide: [email protected] Other publications by the author: • Marsh Moments, with Charles M. Disclaimer: The author, publisher and affiliates assume Anderson no liability for accidents happening to, or injuries • Common Birds of the Arcata Marsh sustained by readers who engage in activities described & Wildlife Sanctuary, with Ken in this book. Burton and David Fix 2 Redwood s National Table of Contents N Park Elk Head 5 Trinidad Moonstone 4 The Setting: Beach Mouth of 3 A Brief Geologic History of Mad River Northern California ........................... 4 McKinleyville Pleistocene Epoch .............................. 6 Arcata The Sites: AREA MAP 101 1. Scotia Bluffs .................................. 7 Eureka 2. Centerville Beach .......................... 9 3. Moonstone Beach ........................ 11 4. Mouth of the Mad River .............. 13 Fortuna 5. Elk Head ...................................... 15 Centerville 211 Beach 2 Ferndale Glossary ............................................. 17 Scotia References .......................................... 17 Scotia 1 Bluffs 5 mi. 10 km Finding Fossils Humboldt County, California offers an impressive array of interesting geologic features exposed by the ocean and local rivers. These layers of deep time contain evidence of conditions on earth and the ancient creatures who lived here millions of years ago. Their fossil remains have been preserved and can be uncovered at several sites in the area. In this guide, you will find maps, directions and samples of the kind of specimens that can be discovered. All it takes is curiosity, a desire to learn more, and the proper tools. Basic equipment for field geology includes: • Hand trowel • Compass • Field camera • Ruler • Rock hammer • Eye protection • Work gloves • Hand lens • Waterproof notebook • Small plastic bags • Pencil, marker • Boots, hat, sunscreen Whenever you venture into the field, take water and maps, allow enough time, and be aware of the weather conditions, tide levels and other cautions for the area. Always respect private property and the environment when fossil hunting. Leave specimens for future explorers. 3 Geologic Time Scale YEARS BEFORE EON ERA PERIOD PRESENT EPOCH (million) Age of man QUATERNARY HOLOCENE Mad River & Elk Head fossils 0.01 Moonstone Beach fossils PLEISTOCENE 1.64 Centerville Beach PLIOCENE fossils NEOGENE 5.2 Scotia Bluffs fossils MIOCENE 24 OLIGOCENE 33.5 CENOZOIC EOCENE PALEOGENE 55 PALEOCENE Mass extinction – 66 dinosaurs replaced CRETACEOUS 144 JURASSIC Age of dinosaurs 208 Mass extinction MESOZOIC TRIASSIC PHANEROZOIC 248 Largest mass extinction – 95% of all PERMIAN species wiped out 286 PENNSYLVANIAN 325 Age of plants MISSISSIPPIAN 360 Mass extinction DEVONIAN 408 First fish PALEOZOIC SILURIAN 438 ORDOVICIAN 505 Mass extinction CAMBRIAN 543 Explosion of animal life VENDIAN Eukaryotes appear Age of stromatolites 2500 3500 First fossils – Prokaryotes ARCHAEN PROTEROZOIC 4500 Solar system & earth formed 4 The Setting: a Brief Geologic History of Northern California Between Fire and Water with the small islands, was scraped off by the westward- ook around you! The spectacular sea cliffs on the moving North American plate and added to its leading beautiful Northern California coast are the leading edge. L edge of the North American tectonic plate. The ground beneath your feet was once on the ocean Mesozoic activity bottom! Our area is composed mainly of the Franciscan About 200 million years ago, during the age of dinosaurs, complex, which is an assemblage of sedimentary and the supercontinent of Pangea began to break up, creating volcanic rocks formed in a marine environment. Sand the North American plate. The early western continental and mud deposited on the sea floor over millions of years margin became graywacke sandstone and shale. Undersea ridges extended spewed volcanic basalt in bulging pillows. Some magma from what is became small islands. Mafic greenstone was sheared and now southern heated under pressure to form serpentinite. Billions of tiny California, sea creatures accumulated on the bottom to become layers up along of ribbon chert and limestone. This seafloor material, along the eastern borders of Nevada, Oregon and Washington, so our area was submerged. • As this plate broke away from the European continent and moved westward, Figure 1 – Configuration of continents 200 million years ago Figure 2 – California 100 mill. yrs. ago • Approximate position of NW California it overtopped Source: Ron Blakely, NAU Geology, 2008 5 Plate Tectonics – Cascadia Subduction Zone • Cascade Range V o l c a n Juan i c De Fuca A JUAN r Ridge c DE FUCA Figure 3 – Configuration of continents 140 million years ago. PLATE • Approximate position of NW California Mt. St. Helens the Farallon plate. The subduction zone resulted in the collision and accretion of belts of oceanic rock that built NORTH AMERICAN the continental margin westward, and filled in the northern Gorda portion of what is now California with this mélange. Ridge PLATE (Figure 2) The diving Farallon plate melted at depth, causing chains of Mt. Shasta andesitic volcanoes and plutons of granitic magma to form PACIFIC GORDA inland. Plutonic rocks from this period are found in the PLATE PLATE Klamath Mountains and Sierra Nevada. The Farallon plate Spreading Mt. Lassen was then completely subducted and consumed beneath the Zone Subduction North American plate. Zone Cenozoic activity After the dinosaurs died out, about 28 million years ago, the North American plate collided with the Pacific Gorda Ridge Mt. Shasta Mt. Lassen plate along the San Andreas transform fault. The North American plate ceased its westward movement and NORTH began a more southwest course, sliding past the Pacific Spreading AMERICAN plate, rather than overtopping it. These shearing forces PLATE metamorphically deformed greenstone from the ocean floor PACIFIC GORDA to create serpentinite. This formation decomposes through PLATE PLATE Subduction weathering to form “blue goo” – unstable blue-gray mud found in our area. The North American plate then came in Figure 5 – The mechanics of subduction and volcanic arcs contact with the Juan de Fuca plate and the Gorda Plate, After Humboldt State University, Geology Dept., 1996. which subducted and began to melt at depth. The resulting magma surfaced in a volcanic arc to form the Cascade range, including Mt. Lassen and Mt. Shasta. (Figure 5) Quarternary events The plates continue their movements to the present day, and are responsible for the numerous earthquakes felt along the California coast. Sediment washed from the land by riv- ers is deposited in layers of mud and sand along the coast. • Most of the fossils found in our area are quite recent, geo- logically speaking. They were deposited along the coast in environments quite similar to those we see today. Many of the species of sea creatures have evloved slowly, with their contemporary counterparts looking much the same as they do now. The remains of sea creatures that lived here were cov- ered by beach sand and mud brought in by rivers, which Figure 4 – Configuration of continents 65 million years ago consolidated and preserved them. The sea cliffs in which • Approximate position of NW California the fossil deposits are found have been uplifted by tectonic Source: Institute for Geophysics, University of Texas at Austin, 1997 activity and worn away by the action of ocean waves. 6 Merriam’s pleistocene epoch Teratorn California Laurel Shasta Ground Sloth Pliohippus Mastodon Columbian Chaparral Mammoth Dawn Stag- Redwood moose Sabertoothed Cat Red-legged Frog Primrose Dragonfly Cockle Dogwinkle Pacific Scallop Moon Snail Limpet Sand Dollar Figure 6 – A representation of the flora and fauna that may have existed in California around the time most of the invertebrate fossils we find were deposited. Illustration by Leslie Scopes Anderson. Source: National Academy of Sciences, 2008 7 Site One: Sandstone cliffs and Scotia Bluffs trail scotia Bluffs Railroad bridge showing gaps! his location involves a long walk, but yields many Cockles impressive specimens. The Scottia Bluffs Sandstone s T is part of the upper Wildcat Group, composed of N massive tan and grey fine-grained, poorly consoli- dated sandstone with some mudstone. This sedimentary layer was deposited in a shallow marine environment around 2 million years ago in the Pleistocene epoch. In addition to the shell
Load more

Recommended publications
  • Cambridge University Press 978-1-108-44568-9 — Active Faults of the World Robert Yeats Index More Information
    Cambridge University Press 978-1-108-44568-9 — Active Faults of the World Robert Yeats Index More Information Index Abancay Deflection, 201, 204–206, 223 Allmendinger, R. W., 206 Abant, Turkey, earthquake of 1957 Ms 7.0, 286 allochthonous terranes, 26 Abdrakhmatov, K. Y., 381, 383 Alpine fault, New Zealand, 482, 486, 489–490, 493 Abercrombie, R. E., 461, 464 Alps, 245, 249 Abers, G. A., 475–477 Alquist-Priolo Act, California, 75 Abidin, H. Z., 464 Altay Range, 384–387 Abiz, Iran, fault, 318 Alteriis, G., 251 Acambay graben, Mexico, 182 Altiplano Plateau, 190, 191, 200, 204, 205, 222 Acambay, Mexico, earthquake of 1912 Ms 6.7, 181 Altunel, E., 305, 322 Accra, Ghana, earthquake of 1939 M 6.4, 235 Altyn Tagh fault, 336, 355, 358, 360, 362, 364–366, accreted terrane, 3 378 Acocella, V., 234 Alvarado, P., 210, 214 active fault front, 408 Álvarez-Marrón, J. M., 219 Adamek, S., 170 Amaziahu, Dead Sea, fault, 297 Adams, J., 52, 66, 71–73, 87, 494 Ambraseys, N. N., 226, 229–231, 234, 259, 264, 275, Adria, 249, 250 277, 286, 288–290, 292, 296, 300, 301, 311, 321, Afar Triangle and triple junction, 226, 227, 231–233, 328, 334, 339, 341, 352, 353 237 Ammon, C. J., 464 Afghan (Helmand) block, 318 Amuri, New Zealand, earthquake of 1888 Mw 7–7.3, 486 Agadir, Morocco, earthquake of 1960 Ms 5.9, 243 Amurian Plate, 389, 399 Age of Enlightenment, 239 Anatolia Plate, 263, 268, 292, 293 Agua Blanca fault, Baja California, 107 Ancash, Peru, earthquake of 1946 M 6.3 to 6.9, 201 Aguilera, J., vii, 79, 138, 189 Ancón fault, Venezuela, 166 Airy, G.
    [Show full text]
  • Lower Eel River and Van Duzen River Juvenile Coho Salmon (Oncorhynchus Kisutch) Spatial Structure Survey 2013-2016 Summary Report
    Pacific States Marine Fisheries Commission in partnership with the State of California Department of Fish and Wildlife and Humboldt Redwood Company Summary Report to the California Department of Fish and Wildlife Fisheries Restoration Grant Program Grantee Agreement: P1210516 Lower Eel River and Van Duzen River Juvenile Coho Salmon (Oncorhynchus kisutch) Spatial Structure Survey 2013-2016 Summary Report Prepared by: David Lam and Sharon Powers December 2016 Abstract Monitoring of coho salmon population spatial structure was conducted, as a component of the California Department of Fish and Wildlife’s Coastal Salmonid Monitoring Program, in the lower Eel River and its tributaries, inclusive of the Van Duzen River, in 2013, 2014, 2015, and 2016. Potential coho salmon habitat within the lower Eel River and Van Duzen River study areas was segmented into a sample frame of 204 one-to-three kilometer stream survey reaches. Annually, a randomly selected subset of sample frame stream reaches was monitored by direct observation. Using mask and snorkel, surveyors conducted two independent pass dive observations to estimate fish species presence and numbers. A total of 211 surveys were conducted on 163 reaches, with 2,755 pools surveyed during the summers of 2013, 2014, 2015, and 2016. Coho salmon were observed in 13.5% of reaches and 7.5% of pools surveyed, and the percent of the study area occupied by coho salmon juveniles was estimated at 7% in 2013 and 2014, 3% in 2015, and 4% in 2016. i Table of Contents Abstract .........................................................................................................................................................
    [Show full text]
  • Geological Survey
    DEPABTMENT OF THE INTEKIOR BULLETIN OF THE UNITED STATES GEOLOGICAL SURVEY N~o. 151 WASHINGTON GOVERNMENT PRINTING OFFICE 1898 UNITED STATES GEOLOGICAL SURVEY CHARLES D. WALCOTT, DIEECTOR THE LOWER CRETACEOUS GRYPMAS OF THK TEX.AS REGION ROBERT THOMAS HILL THOMAS WAYLA'ND VAUGHAN WASHINGTON GOVERNMENT FEINTING OFFICE 18.98 THE LOWER CRETACEOUS GRYPHJ1AS OF THE TEXAS REGION. BY I EOBEET THOMAS HILL and THOMAS WAYLAND VAUGHAN. CONTENTS. Page. Letter of transmittal....._..........._....._ ............................ 11 Introduction ...---._._....__................._....._.__............._...._ 13 The fossil oysters of the Texas region.._._.._.___._-..-._._......-..--.... 23 Classification of the Ostreidae. .. ...-...---..-.......-.....-.-............ 24 Historical statement of the discovery in the Texas region of the forms referred to Gryphsea pitcher! Morton ................................ 33 Gryphaea corrugata Say._______._._..__..__...__.,_._.________...____.._ 33 Gryphsea pitcheri Morton............................................... 34 Roemer's Gryphsea pitcheri............................................ 35 Marcou's Gryphsea pitcheri............................................ 35 Blake's Gryphaea pitcheri............................................. 36 Schiel's Gryphsea pitcheri...........................,.:................ 36 Hall's Gryphsea pitcheri (= G. dilatata var. tucumcarii Marcou) ...... 36 Heilprin's Gryphaea pitcheri.....'..................................... 37 Gryphaea pitcheri var. hilli Cragin...................................
    [Show full text]
  • This Report Is Preliminary and Has Not Bee Reviewed for Conformity with US
    UNITED STATES DEPARTMENT OF THE INTERIOR GEOLOGICAL SURVEY Northeast-trending subcrustal fault transects western Washington by Kenneth F. Fox, Jr.* Open-File Report 83-398 This report is preliminary and has not bee reviewed for conformity with U.S Geological Survey editorial standards and stratigraphic nomenclature. *U.S. Geological Survey 3^5 Middlefield Road Menlo Park, California 9^025 Page Table of Contents Tectonic setting......................................................... 1 Seisraicity............................................................... 4 Discussion............................................................... 4 References cited......................................................... 6 Figures Figure 1. Magnetic anomalies in the northeastern Pacific................ 8 Figure 2. Bathymetry at intersection of Columbia lineament and Blanco fracture zone................................................. 9 Figure 3. Plane vector representation of movement of Gorda plate........ 10 Figure 4. Reconstruction of Pacific-Juan de Fuca plate geometry 2 m.y. before present................................................ 11 Figure 5. Epicenters of historical earthquakes with intensity greater than V........................................................ 12 TECTONIC SETTING The north-trending magnetic anomalies of the Juan de Fuca plate are off­ set along two conspicuous northeast-trending lineaments (fig. 1), named the Columbia offset and the Destruction offset by Carlson (1981). The northeast­ ward projections of these lineaments intersect the continental area of western Washington, hence are of potential significance to the tectonics of the Pacific Northwest region. Pavoni (1966) suggested that these lineaments were left-lateral faults, and that the Columbia, 280 km in length, had 52 km of offset, and the Destruction, with a length of 370 km, had 75 km of offset. Based on Vine's (1968) correlation of the magnetic anomalies mapped in this area by Raff and Mason (1961), with the magnetic reversal time scale, Silver (1971b, p.
    [Show full text]
  • South Fork Eel River & Tributaries PROPOSED WILD & SCENIC
    Management Agency: South Fork Eel River & Tributaries Bureau of Land Management ~ BLM Arcata Field Office PROPOSED WILD & SCENIC RIVERS University of California ~ Angelo Coast Range Reserve These proposed Wild and Scenic Rivers support threatened Location: Mendocino County and endangered populations of salmon and steelhead and CA 2nd Congressional District rare plants. They also provide outstanding research Watershed: opportunities of nearly pristine undeveloped watersheds. South Fork Eel River Wild & Scenic River Miles: South Fork Eel River – 12.3 miles South Fork Eel River—12.3 The South Fork Eel River supports the largest concentration Elder Creek—7 of naturally reproducing anadromous fish in the region. East Branch South Fork Eel River—23.1 Cedar Creek—9.6 Federal officials recently identified the river as essential for the recovery of threatened salmon and steelhead. The Outstanding Values: upper portion of this segment is located on the Angelo Anadromous fisheries, ecological, Biosphere Reserve, hydrological, wildlife, recreation Preserve managed for wild lands research by the University of California. Angelo Reserve access roads are open to For More Information: public hiking. The lower portion flows through the existing Steve Evans—CalWild [email protected] South Fork Wilderness managed by the BLM. The river (916) 708-3155 offers class IV-V whitewater boating opportunities. The river would be administered through a cooperative management agreement between the BLM and the State of California. Elder Creek – 7 miles This nearly pristine stream is a National Natural Landmark, Hydrologic Benchmark, and a UN-recognized Biosphere Reserve. A tributary of the South Fork Eel River, the creek is an important contributor to the South Fork’s anadromous Front Photo: South Fork Eel River fishery.
    [Show full text]
  • OREGON ESTUARINE INVERTEBRATES an Illustrated Guide to the Common and Important Invertebrate Animals
    OREGON ESTUARINE INVERTEBRATES An Illustrated Guide to the Common and Important Invertebrate Animals By Paul Rudy, Jr. Lynn Hay Rudy Oregon Institute of Marine Biology University of Oregon Charleston, Oregon 97420 Contract No. 79-111 Project Officer Jay F. Watson U.S. Fish and Wildlife Service 500 N.E. Multnomah Street Portland, Oregon 97232 Performed for National Coastal Ecosystems Team Office of Biological Services Fish and Wildlife Service U.S. Department of Interior Washington, D.C. 20240 Table of Contents Introduction CNIDARIA Hydrozoa Aequorea aequorea ................................................................ 6 Obelia longissima .................................................................. 8 Polyorchis penicillatus 10 Tubularia crocea ................................................................. 12 Anthozoa Anthopleura artemisia ................................. 14 Anthopleura elegantissima .................................................. 16 Haliplanella luciae .................................................................. 18 Nematostella vectensis ......................................................... 20 Metridium senile .................................................................... 22 NEMERTEA Amphiporus imparispinosus ................................................ 24 Carinoma mutabilis ................................................................ 26 Cerebratulus californiensis .................................................. 28 Lineus ruber .........................................................................
    [Show full text]
  • Thirsty Eel Oct. 11-Corrections
    1 THE THIRSTY EEL: SUMMER AND WINTER FLOW THRESHOLDS THAT TILT THE EEL 2 RIVER OF NORTHWESTERN CALIFORNIA FROM SALMON-SUPPORTING TO 3 CYANOBACTERIALLY-DEGRADED STATES 4 5 In press, Special Volume, Copeia: Fish out of Water Symposium 6 Mary E. Power1, 7 Keith Bouma-Gregson 2,3 8 Patrick Higgins3, 9 Stephanie M. Carlson4 10 11 12 13 14 1. Department of Integrative Biology, Univ. California, Berkeley, Berkeley, CA 94720; Email: 15 [email protected] 16 17 2. Department of Integrative Biology, Univ. California, Berkeley, Berkeley, CA 94720; Email: 18 [email protected]> 19 20 3. Eel River Recovery Project, Garberville CA 95542 www.eelriverrecovery.org; Email: 21 [email protected] 22 23 4. Environmental Sciences, Policy and Management, University of California, Berkeley, Berkeley, CA 24 94720; Email: [email protected] 25 26 27 Running head: Discharge-mediated food web states 28 29 Key words: cyanobacteria, discharge extremes, drought, food webs, salmonids, tipping points 30 31 Although it flows through regions of Northwestern California that are thought to be relatively well- 32 watered, the Eel River is increasingly stressed by drought and water withdrawals. We discuss how critical 33 threshold changes in summer discharge can potentially tilt the Eel from a recovering salmon-supporting 34 ecosystem toward a cyanobacterially-degraded one. To maintain food webs and habitats that support 35 salmonids and suppress harmful cyanobacteria, summer discharge must be sufficient to connect mainstem 36 pools hydrologically with gently moving, cool base flow. Rearing salmon and steelhead can survive even 37 in pools that become isolated during summer low flows if hyporheic exchange is sufficient.
    [Show full text]
  • Pectínidos Pliocenos De La Cuenca De Vejer (Cádiz, So De España)
    ISSN: 0211-8327 Studia Geologica Salmanticensia, 44 (1): pp. 91-140 PECTÍNIDOS PLIOCENOS DE LA CUENCA DE VEJER (CÁDIZ, SO DE ESPAÑA) [Pliocene pectinids from the Vejer Basin (Cadiz, SW Spain)] Alberto RICO-GARCÍA (*) (*): Departamento de Geología. Universidad de Salamanca. Facultad de Ciencias. Plaza de la Merced, s/n. 37008 Salamanca. Correo-e: [email protected] (FECHA DE RECEPCIÓN: 2008-04-01) (FECHA DE ADMISIÓN: 2008-04-15) BIBLID [0211-8327 (2008) 44 (1); 91-140] RESUMEN: El estudio de los pectínidos (Bivalvia, Mollusca) en sedimentos pliocenos de la Cuenca de Vejer de la Frontera (Cádiz, SO España) permite determinar 13 especies, agrupadas en 8 géneros, ampliando la información previa en la zona de esta familia de bivalvos en 5 especies. La presencia de M. pesfelis, F. flexuosus, P. excisum, P. jacobaeus y P. maximus nos permite confirmar y corroborar la edad de Plioceno aportada por la microfauna. A su vez, la existencia de M. latissima, P. benedictus y P. excisum nos permite acotar la posición cronoestratigráfica hasta cerca de los 3,0 Ma. Las asociaciones dominantes en los sedimentos pliocenos apuntan a medios marinos someros, con fondos detríticos y energías variables, sometidos a la acción de tormentas, corroborado por la impronta tafonómica, como pueden ser sistemas de playa- duna y ambientes submareales donde se desarrollan barras y canales. Palabras clave: Pectinidae, Bivalvia, Plioceno, Cuenca de Vejer, Cádiz, SO España. ABSTRACT: This study has been carried out in pectinids (Bivalvia, Mollusca) of pliocene sediments from Vejer de la Frontera basin (Cádiz, SW Spain). The main results of this research has been the taxonomic determination of 8 genders and 13 species, rising previous pectinids information in this zone.
    [Show full text]
  • Geology and Ground-Water Features of the Eureka Area Humboldt County, California
    Geology and Ground-Water Features of the Eureka Area Humboldt County, California By R, E. EVENSON GEOLOGICAL SURVEY WATER-SUPPLY PAPER 1470 Prepared in cooperation with the California Department of Water Resources UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1959 UNITED STATES DEPARTMENT OF THE INTERIOR FRED A. S EATON, Secretary GEOLOGICAL SURVEY Thomas B. Nolan, Director The U. S. Geological Survey Library has cataloged this publication as follows: Evenson, Robert Edward, 1924- Geology and ground-water features of the Eureka area, Humboldt County, California. Prepared in cooperation with the California Dept. of Water Eesources. Washing­ ton, U. S. Govt. Print. Off., 1959 iv, 80 p. maps, diagrs., tables. 25 cm. (U. S. Geological Survey Water-supply paper 1470) Part of illustrative matter fold. col. in pocket. Bibliography: p. 77. 1. Water-supply California Humboldt Co. 2. Water, Under­ ground California Humboldt Co. i. Title: Eureka area, Hum­ boldt County, California. (Series) TC801.U2 no. 1470 551.490979412 GS 59-169 copy 2. GB1025.C2E9 For sale by the Superintendent of Documents, U. S. Government Printing Office Washington 25, D. C. CONTENTS Page Abstract___-_____-__--_--_-_-_________-__--_--_-_-______ ___ 1 Introduction._____________________________________________________ 2 Purpose and scope of the work________ _________________________ 2 Location and extent of the area_______________-_-__-__--________ 3 Previous work_______________________________________________ 3 Well-numbering system________________________________________
    [Show full text]
  • Detailed Structures of the Subducted Philippine Sea Plate Beneath
    JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 104, NO. B1, PAGES 1015-1033,JANUARY 10, 1999 Detailed structuresof the subductedPhilippine Sea plate beneath northeast Taiwan' A new type of double seismiczone Honn Kao and Ruey-JuinRau Instituteof Earth Sciences,Academia Sinica, Taipei, Taiwan Abstract. We studiedthe detailedstructure of the subductedPhilippine Sea plate beneath northeastTaiwan whereoblique subduction, regional collision, and back arc openingare all activelyoccurring. Simultaneousinversion for velocitystructure and earthquakehypocenters areperformed using the vast,high-quality data recorded by the TaiwanSeismic Network. We furthersupplement the inversionresults with earthquakesource parameters determined from inversionof teleseismicP and $H waveforms,a criticalstep to definethe positionof plateinterface and the stateof strainwithin the subductedslab. The mostinteresting feature is that relocatedhypocenters tend to occuralong a two-layeredstructure. The upperlayer is locatedimmediately below the plate interfaceand extendsdown to 70-80 krn at a dip of 40ø- 50ø. Below approximately100 km, the dip increasesdramatically to 700-80ø. The lower layer commencesat 45-50 km andstays approximately parallel to the upperlayer with a separationof 15+5 km in betweendown to 70-80 km. Below thatthe separationdecreases andthe two layersseem to graduallymerge into one Wadati-BenioffZone. We proposeto term the classicdouble seismic zones observed beneath Japan and Kuril as "type I" andthat we observedas "typeII," respectively.A globalsurvey indicates that type II doubleseismic zonesare alsoobserved in New Zealandnear the southernmostNorth Island,Cascadia, just northof the Mendocinotriple junction, and the Cook Inlet areaof Alaska. All of them are locatednear the terrniniof subductedslabs in a tectonicsetting of obliquesubduction. We interpretthe seismogenesisof type II doubleseismic zones as reflecting the lateralcompres- sivestress between the subductedplate and the adjacentlithosphere (originming from oblique subduction)and the downdipextension (from slabpulling force).
    [Show full text]
  • Eel River Recovery Project Rose Grassroots 2018 Final Report Lower Eel River Salmon Parkway: Restoration, Recreation and Education
    Eel River Recovery Project Rose Grassroots 2018 Final Report Lower Eel River Salmon Parkway: Restoration, Recreation and Education By Pat Higgins and Sal Steinberg for ERRP April 30, 2019 Eel River Recovery Project Rose Grassroots 2018 Final Report Lower Eel River Salmon Parkway: Restoration, Recreation and Education The Rose Foundation awarded the Eel River Recovery project a Grassroots grant: Lower Eel River Salmon Parkway - Restoration, Recreation and Education in June 2018. This grant was performed from August 2018 through January 2019 and tremendous strides were made towards achieving goals in terms of planning for adult Chinook salmon habitat improvement, promoting a river-side trail, and in connecting with Native American youth and sparking their interest in science and ecology. Accomplishments are reported by key deliverable. Restoration: Fostering Collaboration for Lower Eel River Habitat Improvement Eric Stockwell is a river and ocean kayak guide and a long-time Eel River Recovery Project (ERRP) volunteer. As a native of the lower Eel River, he has seen the river’s decline and feels passionate about restoring the area so that it can once again safely support the early run of the magnificent fall Chinook salmon. Eric began floating the river in a kayak and on stand-up paddleboard (SUP) in late August and visited the river daily until Thanksgiving. What he discovered was that half of the lower Eel River had been diverted around an island in the previous winter high water leaving only one salmon holding pool in a four-mile reach, and long, shallow riffles where salmon could strand when moving upstream.
    [Show full text]
  • An Annotated Checklist of the Marine Macroinvertebrates of Alaska David T
    NOAA Professional Paper NMFS 19 An annotated checklist of the marine macroinvertebrates of Alaska David T. Drumm • Katherine P. Maslenikov Robert Van Syoc • James W. Orr • Robert R. Lauth Duane E. Stevenson • Theodore W. Pietsch November 2016 U.S. Department of Commerce NOAA Professional Penny Pritzker Secretary of Commerce National Oceanic Papers NMFS and Atmospheric Administration Kathryn D. Sullivan Scientific Editor* Administrator Richard Langton National Marine National Marine Fisheries Service Fisheries Service Northeast Fisheries Science Center Maine Field Station Eileen Sobeck 17 Godfrey Drive, Suite 1 Assistant Administrator Orono, Maine 04473 for Fisheries Associate Editor Kathryn Dennis National Marine Fisheries Service Office of Science and Technology Economics and Social Analysis Division 1845 Wasp Blvd., Bldg. 178 Honolulu, Hawaii 96818 Managing Editor Shelley Arenas National Marine Fisheries Service Scientific Publications Office 7600 Sand Point Way NE Seattle, Washington 98115 Editorial Committee Ann C. Matarese National Marine Fisheries Service James W. Orr National Marine Fisheries Service The NOAA Professional Paper NMFS (ISSN 1931-4590) series is pub- lished by the Scientific Publications Of- *Bruce Mundy (PIFSC) was Scientific Editor during the fice, National Marine Fisheries Service, scientific editing and preparation of this report. NOAA, 7600 Sand Point Way NE, Seattle, WA 98115. The Secretary of Commerce has The NOAA Professional Paper NMFS series carries peer-reviewed, lengthy original determined that the publication of research reports, taxonomic keys, species synopses, flora and fauna studies, and data- this series is necessary in the transac- intensive reports on investigations in fishery science, engineering, and economics. tion of the public business required by law of this Department.
    [Show full text]