PEE-WISCONSIN DRIFT AND ASSOCIATED DEPOSITS. 63 



Fuller ' and Clapp 2 have found that stratified drift in local patches occurs for several 

 miles south of the limit given in Monograph XXXVIII and that a few drift pebbles occur still 

 farther south. The distribution of these patches of stratified drift is not readily accounted for 

 by the ordinary processes of stream deposition nor by the existence of ponded waters during 

 their deposition. The evidence of an extension of the ice over this region of patchy stratified 

 drift is far from conclusive and the explanation of these features must await further investiga- 

 tion. Cox, 3 many years ago, reported the presence of a granite bowlder on a hillside above the 

 village of Carrsville in Livingston County, Ky., still farther outside the limits of well-defined 

 glacial deposits than the gravels noted by Fuller and Clapp. 



ELLINOIAN AND PRE-ILLINOIAN (?) DEPOSITS. 



COMPLEXITY OF THE BOUNDARY. 



The boundary just delimited is apparently that of the Ulinoian stage of glaciation. In its 

 vicinity in Indiana and at some points some distance back from it certain features are apparent 

 which suggest some complexity of glacial movement and deposition. Whether they are the 

 product of an oscillating ice front in a single stage of glaciation or represent two distinct stages 

 of glaciation remains to be determined. 



Early reports of the Indiana Geological Survey contain a few scattered records of the 

 existence of a black mucky soil interbedded with the marginal drift. As the soils reported are 

 near the glacial boundary, where the upper sheet is practically coterminous with the lower one, 

 they may be interpreted as having been formed during a slight recession of the ice and covered 

 by a fresh advance. Other features, however, suggest greater complexity. Nuggets of copper 

 and certain associated rocks of the Lake Superior region are present in the drift deposits of 

 central Indiana nearly to the glacial boundary and farther east in western and central Ohio, 

 and suggest an ice movement from the Lake Superior region. They apparently occur in the 

 basal portion of the drift, and thus may underlie the drift from the Labrador field. 



BURIED SOIL. 



A special effort was made in the summer of 1903 to determine the character of the interval 

 represented by the buried soil of the marginal portion of the drift, but the definite results hoped 

 for were not fully obtained. Examinations of exposures in the hilly counties in central Indiana 

 developed the fact that flat tracts inclosed among the hills are the best localities for the pres- 

 ervation of the buried soil. Of these tracts the most extensive and, on the whole, the most 

 satisfactory is an area of 50 to 60 square miles in southern Putnam and northern Owen counties, 

 known as the "flatwoods." It is underlain largely by Mississippian limestone, which has a 

 nearly level surface preserved apparently in tabular form. This condition of the underlying 

 rock has much to do with the flatness of the surface. The following beds are exposed in the 

 numerous ravines and road gradings: 



Representative section exposed in ravines in southern Putnam County. 



Feet - 

 Surface silt or clay, white, pebbleless; apparently a correlative of the main loess deposit of the 



Mississippi basin 4_ g 



Soil, black, gummy, or gumbo, with quartz pebbles, representing apparently the Sangamon 



interglacial soil 1-3 



Till, brown, generally with deeply weathered surface, apparently of Ulinoian age 3-15 



Gumbo, black, changing to blue or gray below; generally containing a few pebbles 1-8 



Till, brown, extending to bottom of ravines, in places changing to blue: exposed 5-10 



Twenty feet or more of the black mucky material is reported beneath the upper sheet of till 

 in certain wells in the region, but no exposure exceeding 8 feet was found in ravines. In one 

 exposure the till immediately below the lower soil is blue, and in nearly all it is only slightly 

 oxidized ; indeed, in only one was it found to be highl}- weathered. This exposure, which is in 



1 Fuller, M. L., and Ashley, G. H., op. cit. • Tenth Ann. Kept. Geol. Survey Indiana, 1S78, p. 106. 



* Fuller, M. L., and Clapp, F. G., op. cit. 



