[Illustration: DENVER, COLORADO] _But from these immense prairies may arise one great advantage to the United States, viz., the restriction of our population to some certain limits, and thereby a continuation of the union. Our citizens being so prone to rambling, and extending themselves on the frontiers, will, through necessity, be constrained to limit their extent on the west to the borders of the Missouri and the Mississippi, while they leave the prairies, incapable of cultivation, to the wandering and uncivilized Aborigines of the country. Zebulon Pike_ Exploratory Travels Through The Western Territories of North America comprising a voyage from St. Louis, on the Mississippi, to the source of that river, and a journey through the interior of Louisiana and the north-eastern provinces of New Spain. Performed in the years 1805, 1806, and 1807, by order of the Government of the United States. By Zebulon Montgomery Pike. Published by Paternoster-Row, London, 1811: W. H. Lawrence and Company, Denver, 1889. Quotation from pages 230-231, 1889 edition. The GEOLOGIC STORY of The GREAT PLAINS By DONALD E. TRIMBLE _A nontechnical description of the origin and evolution of the landscape of the Great Plains_ GEOLOGICAL SURVEY BULLETIN 1493 UNITED STATES DEPARTMENT OF THE INTERIOR CECIL D. ANDRUS, _Secretary_ GEOLOGICAL SURVEY H. William Menard, _Director_ [Illustration: U. S. DEPARTMENT OF THE INTERIOR · March 3, 1849] UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON: 1980 Library of Congress Cataloging in Publication Data Trimble, Donald E. The geologic story of the Great Plains. (U.S. Geological Survey Bulletin 1493) Bibliography: p. 50 Includes index. Supt. of Docs. no.: I 19.3: 1493 I. Geology—Great Plains. I. Title. II. Series: United States Geological Survey Bulletin 1493. QE75.B9 no. 1493 [QE71] 557.3s [557.8] 80-607022 For sale by the Superintendent of Documents, U.S. Government Printing Office Washington, D.C. 20402 CONTENTS