Malott: The "American Bottoms" Region 



5 



LOCATION, EXTENT, AND NAME OF THE "AMERICAN 



BOTTOMS" 



The area included in the present discussion is represented 

 on two maps, one of which shows the topography and drain- 

 age and the other the geology. The geologic map carries a 

 small insert of Greene County, showing the location of the 

 mapped area within the county. The ''American Bottoms" 

 proper are situated in T. 7 N., 3-4 W., and consist of a filled 

 valley about five miles in length and as m.uch as a mile in 

 width. The mapped area includes parts of these townships 

 and a small part of T. 6 N., R. 4 W. The entire mapped 

 area comiprises about 40 square miles. It will be seen by 

 reference to the geologic map that most of the area lies within 

 the driftless portion of the state, but that the eastern margin 

 of the Illinois Glacial Lobe affected the western edge. A 

 greater area is mapped than is directly concerned with the 

 phenomena of the "American Bottoms". Beech Creek valley 

 is in no way connected with the "American Bottoms", but 

 its inclusion on the map gives clearness to the position and 

 succession of the rock formations, and brings out the con- 

 trasted elevations of these two valleys. It will be seen that 

 the presence and position of certain kinds of rock are of the 

 very first importance in preserving the broad, flat surface of 

 the "American Bottoms", which have resulted from the filling 

 of a pre-glacial valley in front of the Illinois Glacial Lobe. 



Just why certain elevated, broad, alluvial terraces adja- 

 cent to streams, or certain broad, filled valleys should so 

 frequently be called "American Bottoms" has never been 

 made clear to the writer. The first description and attempted 

 explanation of the "American Bottoms" of eastern Greene 

 County is by G. H. Ashley in the Twenty-Third Annual Re- 

 port of the Indiana Department of Geology and Natural 

 Resources for 1898, from notes made by C. E. Siebenthal. 

 Ashley does not propose the name "American Bottoms" for 

 the broad, flat, filled valley, but says that this name has been 

 given to it. The only other mention of the region in geologic 

 literatures is in Monograph XXXVIII, of the United States 

 Geological Survey, where Leverett, using Siebenthal's notes, 

 calls attention to the filled valley as having been the site of 

 a glacial lake "now known as the 'American Bottom' ". It 

 is not clear whether Siebenthal gave the area the name which 

 it now bears, or whether the name had been previously in use. 



