U.S. Geological Survey


PART 1 - TABLE OF CONTENTS, and INTRODUCTION

    The following document was scanned from Professional Paper 901, which is out 
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*Page I*


EXPLANATORY TEXT TO ACCOMPANY THE GEOLOGIC MAP

OF THE UNITED STATES


By Philip B. King and Helen M. Beikman






Geological Survey Professional Paper 901













UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON:1974






*Page II*


UNITED STATES DEPARTMENT OF THE INTERIOR

ROGERS C. B. MORTON, Secretary


GEOLOGICAL SURVEY
V. E. McKelvey, Director




Library of Congress catalog - card No. 74-600169





For Sale by the Superintendent of Documents, U.S. Government Printing
Office Washington, D.C. 20402 - Price $1.25 (paper cover)
Stock Number 2401-02573


*Page III*



CONTENTS


     
         Introduction  ------------------------------------------- 1
Previous geologic maps of the United States ------------- 1 Sources of information ------------------------------- 1 Maps published before 1860 -------------------------- 1 Maps between 1860 and 1880 ------------------------- 7 Maps between 1880 and 1930 ------------------------- 7 The Geologic Map of the United States of 1932 ------ 9
The Geologic Map of the United States ------------------ 10 History of the present project----------------------- 10 Sources of the Geologic Map ------------------------- 11 Uses of the Geologic Map --------------------------- 18 Methods of compilation ----------------------------- 18 Contents of the Geologic Map ------------------------ 20 Classification of the rock units -------------------- 21 Symbolization of rock units ------------------------ 25 Representation of faults ---------------------------- 28 Representation of contacts -------------------------- 31 Subcrop geology ------------------------------------- 31 Northern Interior States ------------------------- 31 Eolian deposits --------------------------------- 35 Atlantic Coastal Plain---------------------------- 36 Radiating strikes------------------------------------ 36 References cited---------------------------------------- 38






ILLUSTRATIONS


FIGURE 1. Geology of the United States as represented by Maclure 
              (1817) ---------------------------------------------------- 1
              
       2. Geology of the United States and adjacent parts of Canada
              as represented by Lyell (1845)  --------------------------- 4
              
       3. Geology of the United States and adjacent parts of Canada
              as represented by Marcou (1855)  -------------------------- 5
              
       4. Geology of the United States and adjacent parts of Canada
              as represented by Edward Hitchcock (1854) ----------------- 6
              
       5. Index map showing areas represented geologically on McGee map
              of 1885, areas added or revised on the McGee map of 1894,
              and additional coverage based on less exact information on
              the C. H. Hitchcock map of 1887 --------------------------- 8
              
       6. Index map of Texas, showing areas covered by different 
             sources used on the Geologic Map -------------------------- 17
             
       7. Index map of the United States, showing areas covered by the
             different sources used for the subsea contours on the
             Geologic Map ---------------------------------------------- 19
             
       8. Geologic maps of the Sandia Mountains, New Mexico, to
             illustrate the process of generalizing data for the
             Geologic Map of the United States ------------------------- 22
             
       9. Map of the Great Basin in Nevada and Utah, showing
             regional extent of major low-angle thrust faults that are
             represented on the Geologic Map of the United States as 
             exposed fragments in the mountain areas ------------------- 29
             
      1O. Circular faults shown on the Geologic Map of the United
             States ---------------------------------------------------- 30
             
      11. Maps of eastern South Dakota, to illustrate problems of
             representing bedrock geology in areas with extensive cover
             of surficial deposits ------------------------------------- 32
             
      12. Generalized geologic map of eastern Middle Western States, to
             show relations of subcrop geology to preglacial river
             systems --------------------------------------------------- 33
             
      13. Geologic map of northern Minnesota, showing the extent of
             thin Upper Cretaceous deposits (Coleraine Formation) that
             are not represented on the Geologic Map of the United
             States ---------------------------------------------------- 34
             
      14. Map of western Nebraska, showing bedrock geology as represented
             on the Geologic Map of the United States, superposed on
             which are the areas of Quaternary sand dunes and drifted
             sand (Sand Hills Formation) as represented on the Geologic
             Map of the United States of 1932 and by Thorp and 
             Smith (1952) ---------------------------------------------- 35
             
      15. Geologic map of the Atlantic Coastal Plain in Maryland,
             Delaware, and New Jersey, showing the relation of the
             bedrock units that appear on the Geologic Map of the United
             States to surficial deposits of Quaternary and late
             Tertiary age ---------------------------------------------- 37
             
      16. Map of the southern Midcontinent region in Oklahoma, Arkansas,
             and Texas, showing "radiating strikes" in Paleozoic and
             Cretaceous rocks ------------------------------------------ 38






TABLE


TABLE 1. Comparison between "American" and "International" systems
             of coloring stratified rocks on maps ---------------------- 27




*Page 1*


EXPLANATORY TEXT TO ACCOMPANY THE
GEOLOGIC MAP OF THE UNITED STATES



By Philip B. King and Helen M. Beikman



INTRODUCTION

The U.S. Geological Survey has published a new Geologic Map of the United States (exclusive of Alaska and Hawaii) on a scale of 1:2,500,000, which was compiled between 1967 and 1971 by Philip B. King and Helen M. Beikman, with geologic cartography by Gertrude J. Edmonston. The map replaces the now outdated Geologic Map of the United States on the same scale, which was compiled by George W. Stose and Olof A. Ljungstedt and was issued by the U.S. Geological Survey in l932.

This report is intended to supplement the new map and to provide background information to assist its user in interpreting it. It describes the historical antecedents of the map and the sources from which the map was compiled and discusses various general topics related to it. Succeeding reports will amplify the necessarily brief descriptions of the map units which appear in its legend and will deal at length with specific geological problems in the United States, insofar as they relate to representation of the features in map form.





Part 2 - Previous Geologic Maps of the U.S.


U.S. DEPARTMENT OF THE INTERIOR
U.S. GEOLOGICAL SURVEY

Eastern Mineral Resources Team

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Last revised 11-13-98