Nebraska in relation to the problems of Pleistocene stratigraphy

Abstract

Introduction. CONTENTS. Glacial and fluviatile Pleistocene materials in Nebraska. Age of the Loveland loess. Pleistocene classiflcation. Correlation with Europe. Glacial or interglacial. Glacial or interglacial loess. Duration of the advances. Post-Loveland pre-Peorian erosion. Geomorphology of the Great Plains and Pleistocene history. Sources of loess materials. River valleys and loess deposition. Dust storms. The Oitell'/l,s zone. The problem of animal survival. Aftonian (?) fauna. Antiquity of varved sediments. Conclusions. ABSTRACT. Nebraska is so peculiarly situated with respect to Pleistocene deposits of glacial, fluviatile, and eolian origin that it holds the key to the solution of many important problems of the stratigraphy of that period. A brief outline of the Pleistocene geology of Nebraska with several illustrations is followed by a statement of and brief discussion of several of these problems. The main problems touched upon are: age of the Loveland loess, Pleistocene classification, correlation with Europe, the need for a better understanding of what is meant by glacial and interglacial, the problem of and interglacial loess, the duration of the advances, post-Loveland pre-Peorian erosion, the geomorphology of the Great Plains as an aid in understanding Pleistocene history, sources of loess materials, the relation of river valleys to the origin and deposition of the loess, the significance of the lesson of the dust storms, the Oitellus zone and the antiquity of Man, problem of animal survival and Pleistocene faunal succession, what constitutes the Aftonian fauna, and the problems of varved sediments. Pleistocene geology still is in the experimental stage. Nebraska is so peculiarly situated with respect to Pleistocene deposits of glacial, fluviatile, and eolian origin that it holds the key to the solution of many important problems of the stratigraphy of that period. A brief outline of the Pleistocene geology of Nebraska with several illustrations is followed by a statement of and brief discussion of several of these problems. The main problems touched upon are: age of the Loveland loess, Pleistocene classification, correlation with Europe, the need for a better understanding of what is meant by glacial and interglacial, the problem of and interglacial loess, the duration of the advances, post-Loveland pre-Peorian erosion, the geomorphology of the Great Plains as an aid in understanding Pleistocene history, sources of loess materials, the relation of river valleys to the origin and deposition of the loess, the significance of the lesson of the dust storms, the Oitellus zone and the antiquity of Man, problem of animal survival and Pleistocene faunal succession, what constitutes the Aftonian fauna, and the problems of varved sediments. Pleistocene geology still is in the experimental stage. • This paper. now completely revised was presented first in brief by Mr. C. Bertrand Schultz in the absence of the writer at the International Symposium on Early Man, Philadelphia Academy of Natural Sciences, March, 1987. AM. JOUR. SC.-VOL. 287, No. 12, DECEMBER, 1989. 56 852 A. L. Lug'Tlr-N ebraska in Relation to the