STRATIFIED DRIFT 957 



ways, were probably not rare at the time of the maximum 

 extension of the ice, and more or less drainage from the ice must 

 have found its way into them. Wherever this occurred, stratified 

 deposits of drift were made in the lakes, the materials for which 

 were borne into the standing water by the streams which issued 

 from the ice. Deltas must have been formed where well-defined 

 streams entered the lakes, and subaqueous overwash plains'^ 

 where deltas became continuous by lateral growth. The accu- 

 mulation of stratified drift along the ice-ward shores of such 

 lakes must have been rapid, because of the abundant supply of 

 detritus. These materials were probably shifted about more or 

 less by waves and shore currents, and some of them may have 

 been widely distributed. Out from the borders of such lakes, 

 fine silts and clays must have been in process of deposition, at 

 the same time that the coarse materials were being laid down 

 nearer shore. 



Deposition must have taken place in a similar way along the 

 shores of the sea wherever the ice reached it. The silt, sand, 

 gravel, etc., carried to the sea by running water was either 

 deposited at once, or worked over and transported greater or 

 less distances by waves and littoral currents. Such deposits 

 still remain beneath the sea, unless changes of level have 

 brought them above the surface. 



During the maximum extension of an ice-sheet, therefore, 

 there was chance for the development, at its edge or in advance 

 of it, of the following types of stratified drift: (i) kames and 

 kame belts, at the edge of the ice; (2) fluvial plains or valley 

 trains, in virtual contact with the ice at their heads; (3) border 

 plains or overwash plains, in virtual contact with the ice at 

 their upper edges ; (4) ill-defined patches of stratified drift, 

 coarse or fine, near the ice ; (5) subaqueous overwash plains and 

 deltas, formed either in the sea or lakes at or near the edge of the 

 ice ; (6) lacustrine and marine deposits of other sorts, the mate- 

 rials for which were furnished by the waters arising from the ice. 



'Annual Report of the State Geologist of New Jersey for 1S92, p. 99; ibid., 

 1893, P- 266. 



