Bulletin of the Geological Society of America - new book

Purchase of this book includes free trial access to www.million-books.com where you can read more than a million books for free. This is an OCR edition with typos. Excerpt from book: very long interglacial elocb. At several places near the village of Aftou and also west of Oseeola, about 20 miles east of Afton, there are flue outcrops of Nebraskan gumbotil, below which Is Nebraskan drift and above which is Kunsan drift. Moreover, in Dodge township, Union County, there is a splendid section of peat lying on Nebraskan drift and overlain by Kansan drift. This peat bed was described years ago by Savage. The gumbotil and the pent are now the significant evidence of Aftouian time. If the interpretations of the writer are correct, the Aftonlan gravels of Union County have lost much of their former significance, and the type sections, particularly the Grand River section, can no longer be referred to as sections in which it is possible to study the two oldest drift-sheets separated by Aftonian gravels. Presented without notes, with lantern-slide illustrations. The session adjourned about 5.30 o'clock p. m. Sectional Sessions Two additional sections were formed Tuesday afternoon for the reading of papers. The first was presided over by former President A. P. Coleman, with D. F. Hewett acting as secretary. The following papers were presented: WINDROW FORMATION, AX UPLAND GRAVEL FORMATION OF THE DRIFTI. EHf t AXD ADJACENT AREAS OF THE IPPER MISSISSIPPI VALLEY BY F. T. THWAITE8 AND W. H. TWENHOFEL (Abstract) The Windrow formation consists of widely separated patches of quartz and chert gravels, with associated limonite deposits, which occur on the tops of high elevations throughout the driftless area of the upper Mississippi Valley and the adjacent glaciated area to the west and south. The chert pebbles contain fossils, of which the youngest are certainly of Silurian age. The authors have concluded that this formation was river-deposit...