J. 0. Smock—Thickness of the Continental Glacier. 349 
to incipient glaciers, whose melting did much to mix materials 
and round off ledges and bowlders or loose blocks. The 
above, and the slightly rounded rock fragments found near 
them, may have had their origin in some such way. 
The direction of the strize and the grooves are omitted, as 
hot pertinent to the question. Suffice it to say here that they 
indicate a general southwest movement. 
That such an upper limit of the glacier was probable has 
been indicated repeatedly by Professor James D. Dana in his 
Manual of Geology and in articles in this Journal. In one 
of these latter, on the Mohawk Valley Glacier, he says: “On 
the Catskills the glacier scratches reach to a height of 2235 
feet—the elevation at the Mountain House—and this implies 
the existence of ice and snow to a height of at least 2600 feet ; 
and if the snow had this height over the whole southern pla- 
tean it would have almost completely buried it, with the excep- 
tion of the higher Catskill summits.”"* This language seems 
almost prophetic. But the ice reached higher than Professor 
ana at that time supposed, though still not high enough to 
bury the higher sammits, 
The only mountains in New England which approach the 
height of the Catskills, and are in the same latitude, are Mt. 
Everett in Massachusetts and Greylock, in the same State, but 
little farther to the north. Of the first-named, Professor Dana 
says that its glaciated summit “affords evidence that the ice 
which covered New England in the Glacial Period overtopped 
i Perth Amboy—the distance 
vive a descent to the glacier sur- 
face of less than thirty feet to the mile, and less than one-half 
of adegree. But this rate corresponds closely with that ob- 
— by Professor Geikie for the Scottish Glacier, viz: 1 in 
Greenland glacier and the great 
From what is known of the sier and 
+ the inclination of the 
Antarctic ice-cap we should infer tha 
* This Journal, II, vol. xxxv, p- 249, 
} This Journal, ITI, vol. x, p. 168. 
