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G~~~~!reSpresents the re~lts of al~ost co~tinuous research by the Ne?raska State than 10 y urv~y on TertIary stratlgraphy InN ebraska during a perIod of more clature. c~i r Ith special attention to the present acceptable stratigraphic nomenas'Vbite If. n reAa~ons are presented for the retention of such well-known names ranking. "L ver , 'Fnkaree, and Ogallala, all now redefined and elevated to group an: CO~deredu~ ark", HLoup Riyer':, "Nebras~a beds", and HRepublican River" ~tiO!l IS noted bSTlhte. The apphca~lon of fos~l seed zones to problems ~f correertlary stratI" h ~ table of TertIary formatIons of Nebraska summarIzes the. . .grap Y In Nebraska. ... SA ('O<"p*,t'3ti,,'p PT(>jt-ct of thl' United States Geological Survey nnd the Consen-stion and Sun-eY Di,,-j,,ion of the rnin'rEity of Xf'hra.!>ka.

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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 glacial 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 glacial and interglacial loess, the duration of the glacial 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.