298 ANNUAL OF SCIENTIFIC DISCOVERY. 







perpendicular lines of cleavage frees, the analogy between slate and ice is 

 perfect; but it fails in the point that in ice distinct lamina? are formed, vary- 

 ing in compactness; which, as far as we know, is not the case with slate. 

 Prof. Tyndall's last-named experiment would seem to show that the blue 

 veins are formed by the liquefaction of the ice in lines perpendicular to the 

 direction of pressure. But, in this case, how is the freezing of this water 

 effected? Xot by the winter's cold, which could only affect the surface; nor 

 by regclation, so long at least as the laminae of ice and water are subjected 

 to the pressure which causes the liquefaction. And yet parallel veins of ice 

 and water arc never found in any part of a glacier. The difficulty will be 

 removed when it is proved that pressure will develop in porous ice perpen- 

 dicular veins of compact ice, iciihout previous liquefaction. Lit. Gazette. 



ON THE MARKS OF ANCIENT GLACIERS ON THE GREEN-MOUNTAIN 

 RANGE IN MASSACHUSETTS AND VERMONT. 



At the meeting of the A. A. for the Promotion of Science, 18-59, Mr. C. H. 

 Hitchcock, of Amherst, presented a communication on the above subject, 

 which embodied in itself the results of investigations undertaken under the 

 direction of Professor Edward Hitchcock, upon the mountains west of the 

 Connecticut River, in Massachusetts and Vermont. The following, according 

 to Mr. H., are the chief distinctions between the marks of the ordinary drift 

 and the marks of glaciers : 



1. Glacier stria? differ often widely in direction from drift strias. The drift 

 stria? may be referred to three general directions, to the south, to the 

 southeast, and to the southwest, while the glacier directions are. exceed- 

 ingly various, sometimes coinciding with, and often crossing those left by 

 the drift. 



2. Glacier striae occur only in valleys radiating outwardly from the crests 

 of mountains, or in valleys tributary to a main valley, in which was the 

 principal glacier, while the drift stria? overtop the mountains ; or, when found 

 in valleys, cross them obliquely. 



3. Glacier striae descend from higher to lower levels, except in limited 

 spots, where they may be horizontal. Drift stria? as frequently ascend 

 mountains hundreds of feet. 



4. Drift is spread promiscuously over the surface, and the blocks are a 

 good deal rounded. The detritus of glaciers more or less blocks up the val- 

 leys, and the fragments are frequently quite angular. These, however, are 

 in part covered with other materials, which have descended from the moun- 

 tains. 



Mr. H. then carefully described the marks of an ancient glacier, to be seen 

 in the west part of Hancock, in a valley through which Middlebury River 

 commences to run, and within half a mile of the crest of the Green Moun- 

 tains. Here several ledges of gneissoid rocks have two sets of stria? on 

 them, the one running south 50 east, the other set pointing west 30 south, 

 down the valley. The glacier set are the most prominent; and they cross 

 the drift set at an angle of 70. The force by which the first set was pro- 

 duced was up-hill, towards the crest of the mountain, which, a few miles 

 north of the road, rose some eiirht hundred or one thousand feet above the 

 stria?. The force producing the second, or glacial set, was down-hill, in the 

 direction of the river. 



We find traces of another glacier, passing over the mountain towards Han- 



