[Illustration: Geology of Arches National Park] [Illustration: BALANCED ROCK, guarding The Windows section of Arches National Park. Rock is Slick Rock Member of Entrada Sandstone resting upon crinkly bedded Dewey Bridge Member of the Entrada. White rock in foreground is Navajo Sandstone. La Sal Mountains on right skyline. (Frontispiece)] [Illustration: Graphic Title Page] _The Geologic Story of_ Arches NATIONAL PARK By S. W. Lohman Graphics by John R. Stacy GEOLOGICAL SURVEY BULLETIN 1393 UNITED STATES DEPARTMENT OF THE INTERIOR ROGERS C. B. MORTON, _Secretary_ GEOLOGICAL SURVEY V. E. McKelvey, _Director_ [Illustration: Department of the Interior · March 3, 1949] U.S. GOVERNMENT PRINTING OFFICE: 1975 Library of Congress Cataloging in Publication Data Lohman, Stanley William, 1907- The geologic story of Arches National Park. (Geological Survey Bulletin 1393) Bibliography: p. Includes index. Supt. of Docs. no.: I 19.3:1393 1. Geology—Utah—Arches National Park—Guide-books. 2. Arches National Park, Utah—Guide-books. I. Title. II. Series: United States Geological Survey Bulletin 1393. QE75.B9 No. 1393 [QE170.A7] 557.3′08s [557.92′58] 74-23324 For sale by the Superintendent of Documents, U. S. Government Printing Office Washington, D. C. 20402 Stock Number 024-001-02598-1 Contents