Geology of
Devils Tower
National Monument
Wyoming

By CHARLES S. ROBINSON

A CONTRIBUTION TO GENERAL GEOLOGY

The National Park Service and the Devils Tower Natural History Association wishes to thank the United States Geological Survey for their kind permission to have this Bulletin reprinted with minor changes.

CONTENTS

Page [Abstract] 1 [Introduction] 1 [Geology] 3 [Devils Tower] 3 [Sedimentary rocks] 6 [Spearfish formation] 6 [Gypsum Spring formation] 7 [Sundance formation] 7 [Stockade Beaver shale member] 8 [Hulett sandstone member] 8 [Lak member] 9 [Redwater shale member] 9 [Stream terrace deposits and alluvium] 10 [Talus and landslide material] 10 [Structure] 11 [Geologic history] 11 [Origin of Devils Tower] 12 [Selected bibliography] 13

ILLUSTRATIONS

FIGURE Page [52.—Index map showing location of Devils Tower National Monument] 2 [53.A.—Northwest side of Devils Tower showing how the columns taper or converge and in places unite near the top and are cut by numerous cross-fractures] 4 [B.—Southwest corner of Devils Tower showing the columns flaring out and merging to form the massive base] 4 [54.—Generalized section of the sedimentary rocks of the Devils Tower National Monument] 6

A CONTRIBUTION TO GENERAL GEOLOGY
GEOLOGY OF DEVILS TOWER NATIONAL MONUMENT, WYOMING