é 
Consequences of the Glacial flood. 125 
sions and under similar conditions. But was it by the same 
method ? 
deep, the ice-masses must have been in place in the early part 
of the flood and have projected high above the waters during 
its whole progress. : 
Some of the difficulties are thence the following : | 
(1) In the early part of the flood (when only finer sand 
deposits of the terrace formation were in progress), there is no 
reason to believe that water enough existed in the stream to 
have floated masses 100 to 500 feet or more in diameter and 50 
eet or more thick; for 50 feet of depth, at least, would have 
been required. The above are minimum numbers as no allow-— 
ance is made for waste by melting. oe 
(2) The waters which flowed by the stranded nese Oe os 
the progress of the flood, deposited in their close vicinity beds 
of sand and gravel having the flow-and-plunge structure, and ce 
* Report on the Geology of Massachusetts, 4to, 1841, ii, 370. 
