SEPM Special Publication No. 46 From Shoreline to Abyss: Contributions to Marine Geology in Honor of Francis Parker Shepard Edited by: Robert H. Osborne ISBN 978-1-56576-171-1, catalog 41046 Originally published in print as SEPM Special Publication No. 46, ISBN 0-918985-92-7 Tulsa, Oklahoma, U.S.A., 1991 www.sepm.org Downloaded from http://pubs.geoscienceworld.org/books/book/chapter-pdf/3794983/9781565761711_frontmatter.pdf by guest on 30 September 2021 FROM SHORELINE TO ABYSS CONTRIBUTIONS IN MARINE GEOLOGY IN HONOR OF FRANCIS PARKER SHEPARD o 1 II101 II1011 0 II101 II101 o 101 o II 0 fo Edited by I Robert H Osborne Department of Geological Sciences University Southern I of California Los Angeles CA 90089 0740 Copyright 99 by SEPM Society for Sedimentary Geology Barbara H Lidz Editor of Special Publications Special Publication No 46 Tulsa Oklahoma S U A September 99 Downloaded from http://pubs.geoscienceworld.org/books/book/chapter-pdf/3794983/9781565761711_frontmatter.pdf by guest on 30 September 2021 A PUBLICATION OF SEPM SOCIETY FOR SEDIMENTARY GEOLOGY ISBN 0 918985 92 7 @ 1991 by SEPM Society for Sedimentary Geology P O Box 4756 Tulsa Oklahoma 74131 Printed in the United States of America Downloaded from http://pubs.geoscienceworld.org/books/book/chapter-pdf/3794983/9781565761711_frontmatter.pdf by guest on 30 September 2021 PREFACE Francis P Although Shepard passed away on April 25 rier island development and late Quaternary sea level rise 1985 he left a rich scientific legacy including more than His book Our Changing Coastlines co authored by Wanless 230 and published papers books primarily addressed to the Sr in 1971 has served as a major text dealing with the of submarine study canyons and turbidity currents 101 dynamics and evolution of coastal geology for the last two continental and publications shelves associated sediments decades Two themes that penetrate his work are the rec 46 coastal and 33 processes sediments and marine ognition of the coast as an interface between terrestrial and physiography and tectonics 31 He is best remembered for marine processes and the overlapping time scales associated his work on submarine canyons however his broad range with coastal processes These themes continue to be central of scientific interests and his remarkable to to ability break ongoing investigations of shoreline response to climate new ground in each of these disciplines have served as a eustasy and tectonics model for at least four generations of Shepard students Furthermore Shepard stressed the concepts of littoral cells Upon his retirement from the Scripps Institution of Ocean and their utility for understanding the input transfer and in ography 1964 about 30 of his students presented him outflow of sand within the shore zone The identification with a book of their papers edited by R L Miller entitled of littoral cells and the computation of sediment budgets in Marine Papers Geology Shepard Commemorative Vol within such beach segments remain as fundamental ele ume MacMillan Official retirement meant little to Shepard ments in our understanding of coastal scientific and engi as indicated by the fact that he authored almost another 100 neering problems Peterson and others examine the areal publications including seven books from 1964 to 1985 distribution of active beach widths eolian dune fields a full research career for most The coastal terrace mortals present volume heights and beach grain size data along a was completed in honor of Shepard s innovative leadership 1 OOO km open coastline from Cape Mendocino in northern in marine geology during a highly creative and productive California to Cape Flattery in northernmost Washington professional life of 63 years Inasmuch as the prestigious These data are used to identify the locations and dimensions Francis P Medal for Excellence in Shepard Marine Geol of 42 continuous beach segments each more than 2 km has been awarded SEPM the which occur ogy usually annually by since long along this convergent margin and may was in it is medal established 1966 most appropriate that serve as proxies for possible littoral cells These segments this be in SEPM volume included the Special Publication are related to source and tectonic controls as well as net series littoral transport direction This volume is organized into five parts reflecting Best and Griggs identify the streams draining the Santa s Shepard major areas of scientific interest With the ex Cruz Mountains and 130 kmofcoastal bluffs as the primary of Part I each ception which contains only one paper sec sediment sources in the Santa Cruz Littoral Cell which ex is tion organized principally from global and regional scale tends from San Francisco Bay to Monterey Submarine Can studies to more local ones Where appropriate secondary yon The computed budget shows that sediment input to themes in statements for are presented the introductory each this cell is highly episodic in response to large and infre of the volume To the part personalize the Preface senior quent erosional events Furthermore bluff erosion and high author of each to paper was requested submit a short para stream flow operate at different frequencies than associated graph relating the subject to Shepard and or his research longshore transport and changes in the volumes of sand Much of the Preface was extracted from these paragraphs stored either on the beach or along the inner continental Part I consists of a paper by Emery and Ross that sets shelf may produce appreciable volumes of sand due to their the stage for the volume by providing an overview con large areal extents the evolution of marine the last cerning geology during 50 Although the littoral cell concept is appealing and widely Some idea of the rate of in has years high advance marine ge applied it never been demonstrated that foreshore sand ology is illustrated by the kinds of problems that were being from a given local source actually follows the suggested addressed in s Shepard youth by him and others as com pathway along a substantive portion of a given cell to be with those studied at the close his career pared being of trapped eventually either by a submarine canyon head or In of fact present types investigations were not possible by a point of land Osborne and Yeh use Fourier analysis earlier of because inadequate background information data of detrital quartz grains to identify the local sources and acquisition methods of sampling and study instrumenta grain shape compositions within five divisions of the tion societal needs and funding This history implies that Oceanside Littoral Cell in southern California Each subcell cannot now we accurately forecast studies likely to occur is compositionally distinct and with one notable exception in even the year 2050 though many attempts may be made appears to be internally homogeneous Approximately 36 was one of the in the of the sand Shepard pioneers modem study percent of quartz appears to have been derived beach processes particularly along the Pacific coast of North from adjacent inner continental shelf deposits It is inter Part II which America contains four papers is dedicated esting to note that grain shape differences played an im to his coastal work which at least role in the 1961 spanned four decades portant Shepard and Young paper and the included investigations of classification of coastal Shepard s contribution to an understanding of marine systems nearshore circulation littoral compartmentiliza sedimentary deposits led to a major advance in the inter tion seasonal beach sand transport sea cliff erosion bar pretation of marine strata in the rock record Much of what Downloaded from http://pubs.geoscienceworld.org/books/book/chapter-pdf/3794983/9781565761711_frontmatter.pdf by guest on 30 September 2021 iv PREFACE the re we know about ancient marine deposits has its origins in how modem shelf surfaces evolved By employing his field investigations of modem marine environments The cently developed concepts of sequence stratigraphy they an the formation of shelf different paper by Chiocci and Clifton is example of appli analyze the deposits during stages cation of observations of modem sedimentary processes to of sea level on a variety of passive and active margin the interpretation of Pleistocene nearshore deposits as shelves Their findings advance those of Shepard s initial signed to the Merced Formation which are exposed in sea work by identifying the conditions during falling and low cliffs south of San Francisco California Gravel filled gut stand sea level that determine whether or not the coast will ter casts in the Merced Formation are oriented approxi prograde and whether or not the associated deposits will be mately normal to the inferred shoreline trend accordingly preserved Sea was the areas studied such structures may serve as useful indicators of shoreline The Yellow among shelf by he the size distri trends in other gravelly nearshore deposits Shepard In 1932 identified basic grain and A considerable amount of Shepard s research was dedi bution on the seabed from nautical chart notations the of the River sediment load cated to a better understanding of the origin and evolution showed influence Yellow of continental shelves and slopes the subject of Part III and the occurrence of coarser grained material at the shelf the of this volume For example he published a synthesis of edge In 1949 Shepard and others described area as and addressed sediment texture on the continental shelves of the world in analogous to classic epicontinental