462 MYRON L. FULLER 
this small stream, not over 150 feet in width, was equivalent to 
40 per cent. of that of the Mississippi.* 
The small amounts of the coarse material, compared with the 
amount of clay, is also a significant feature. It shows fully two 
thirds of the detritus brought in by the stream was of the finely 
comminuted quartz flour. The velocity was such that had the 
current come in contact with the subglacial till to any extent the 
percentage of coarse material would have been much greater. Its 
absence indicates, therefore, that practically the entire amount 
must have been derived from the ablation of the ice. The high 
percentage of the finer débris contained within the ice is certainly 
a striking feature. 
Myron L. FULLER. 
MASSACHUSETTS INSTITUTE OF TECHNOLOGY, 
Boston, Mass. 
tJ. B. WoODWORTH, Zoe. cit., 162. 
