58 OSCAR H. HERS HEY 



and which I have referred to as "typical till." It is a stiff, 

 unstratified, light yellowish gray clay, containing irregularly dis- 

 seminated subangular blocks, largel}' of local derivation, but also 

 an appreciable percentage of foreign rock fragments, many of 

 which are Canadian in origin. The Niagara limestone pebbles 

 are next in abundance to the Galena limestone and chert, and 

 are often beautifully striated. A belt of this variety of glacial 

 clay occupies the country between Yellow creek and a high 

 upland area about four miles south of it. Its eastward and 

 westward limits are indefinite, but its length may properly be 

 included within ten miles. It can be observed best by proceed- 

 ing due south from Freeport, where at the distance of about four 

 miles, it will be seen to assume distinct drumloid characters. 

 In particular, one of these pseudo drumlins, while it has a core of 

 stratified sand and gravel, is overlain by an eight-foot stratum of 

 yellow till so nearly identical in constitution with the typical till 

 of a highly glaciated region, that no appreciable difference could 

 be detected. This drumlin (?) is also the best locality in this 

 county for securing finely striated stones. Now, a careful study 

 of the composition of this till belt shows that, [a) the mass of 

 its clay may be referred to abrasion of the silt formations which 

 it frequently overlies : [b) its foreign rock fragments must have 

 been brought into the district by the ice-sheet, but independently 

 of the accumulation of the till, their occurrence in which is an 

 accident of deposition ; [c) the iron in the till was derived from 

 the residuary clay of the region, as was also the large amount of 

 angular and subangular white chert ; and [d ) the subangular 

 Galena limestone blocks which are quite abundant but generally 

 overlooked because of the more attractive appearance of the for- 

 eign drift, must have been derived from the country rock, very 

 close to its present position, by the process which has been 

 described in this paper. 



It may be objected to the first proposition^hat the difference 

 between the till in this limited belt and that in the remainder of 

 the county, may be due to a greatly increased introduction of 

 foreign material along some line as the broad, shallow basin 



