REPRESENTATIVES OF PRE-WISCONSIN TILL 



327 



fact that all of the occurrences noted lie in the southern belt, in 

 which, with the exception of the hills and other prominences, 

 the work of the ice of the last invasion was largely one of 

 deposition. 



Fig. 6. — View of disintegrated ledge of conglomerate, Intervale Park, Brockton. 

 The weathering is supposed to be interglacial in age. 



SUMMARY AND CONCLUSIONS 



1. The Pleistocene ice sheet on its first advance found a 

 somewhat deeply decayed rock surface, many remnants of which 

 are now to be seen. 



2. The erosive power of the first advance was not sufficient 

 to entirely remove the products of decay, for tills evidently com- 

 posed of such products have been found by the writer beneath 

 the ordinary tills of the region. These have been described in 

 this paper. 



3. The older tills are probably the result of the re-working of 



