Malott: The "American Bottoms'' Region 11 



portance physiographically in Indiana. Its outcrop is con- 

 fined to Beech Creek valley in the region here considered, 

 and it is only infrequently seen in position. 



The Ehvren Sandstone and Shale. The lithologic unit 

 succeeding the Reelsville limestone consists of one or more 

 members of sandstone and frequently considerable thicknesses 

 of shale, the whole having a total thickness of 40 to 50 feet. 

 The name proposed for this formation is the Elwren sand- 

 stone, from the vicinity of Elwren in western Monroe County, 

 Ind., where excellent exposures are to be seen in the cuts of 

 the Illinois Central Railway. It fills the interval between 

 the thin Reelsville limestone and the next limestone above. 

 The Elwren sandstone and shale unit is represented on the 

 geologic map by a single convention. In the region of the 

 "American Bottoms" it consists of a sandstone from a few 

 feet up to 30 feet in thickness, and a gray-blue shale, with 

 a maroon streak extending up to the overlying Beech Creek 

 limestone, or to another sandstone member near the top. 

 The latter in places attains a thickness as great as the lower 

 sandstone member. The upper sandstone is thick vs^here the 

 lower sandstone is thin. This latter condition is shown in 

 the typical stratigraphic column taken from Ray's Cave sec- 

 tion along Beech Creek near Ridgeport. The sandstone is 

 usually bedded, but is occasionally massive. The Elwren 

 sandstone and shale unit outcrops on both sides of Beech 

 Creek valley thruout its course, and along the upper part 

 of Cliffy Creek valley. North and east of the extreme north- 

 east corner of the mapped area the Elwren sandstone has 

 unusual thickness, occupying the position of several of the 

 lower units which had been eroded away previous to the 

 deposition of the Elwren sandstone. Topographically the 

 Elwren sandstone gives rise to local benches where it takes 

 on the massive phase, as may be seen in the northwest quar- 

 ter of section 7, on the north side of Beech Creek. Since 

 the sandstones are medium to fine grained and usually con- 

 tain considerable clay, they form slopes rather than bluffs 

 and cliff's. 



The Beech Creek Limestone. The next stratigraphic unit 

 in the Chester Series is the Beech Creek limestone. This 

 name is proposed for the limestone unit which has heretofore 

 been called the ''Middle" or ''Second" limestone of the Ches- 



