

GLACIER BTEIM DISTINGUISHED. 83 



should naturally look for such phenomena : but the explorations there have not had much 

 success. The Green Mountain range, including Hoosac Mountain, which is a continua- 

 tion of the Green Mountains across Massachusetts, has afforded more satisfactory results. 

 The evidence of ancient glaciers on that range was first found in the town of Russell, in 

 Massachusetts, described in a paper on Surface Geology, in the Smithsonian contributions 

 to knowledge. The same paper contains an account of other cases on the main branch of 

 "Westfield river, on Deerfield river, and on the branches of Quechee river, above Wood- 

 stock, in Vermont. Other cases have come to our knowledge, during the survey of the 

 latter State, of a still more decided character, which we shall now describe. They are 

 also exhibited on our Map of the Surface Geology. 



It ought to be premised in this connection that some able geologists regard all the phe- 

 nomena of drift as produced by glaciers. Such, of course, make no such distinction 

 between the different varieties as we do. The difficulties in the way of referring all the 

 drift phenomena in our country to glaciers seem to us insuperable, and we therefore resort 

 to icebergs for common drift, and refer such cases as have the following characters to 

 glaciers. 



1. Glacier striae differ often widely in direction from drift striae, and the stoss side of 

 the ledges is of course very different in reference to the cardinal points. 



2. Glacier striae occur only in valleys radiating outwardly from crests of mountains, 

 while the drift striae overtop the mountains, and when found in valleys frequently cross 

 them obliquely. 



3. Glacier striae descend from higher to lower ends, except in limited spots, where they 

 may be horizontal. Drift striae frequently ascend mountains hundreds of feet high, whose 

 stoss side is the lower side. 



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 valleys, or lies strewed 

 along the sides of the valleys, and the fragments are frequently quite angular. These 

 blocks, however, are sometimes covered more or less with materials that have been modi- 

 fied by water, flowing for ages down the same valleys. 



Guided by these principles we give the following examples of what we regard as cases 

 of ancient glaciers in Vermont. In regard to some of them we still feel in doubt, partly 

 because we have not been able to give them the requisite investigation. 



Perhaps the most satisfactory cases of this sort occur on the road across the Green 

 Mountains through Ripton and Hancock to Rochester. We follow a branch of Middle- 

 bury River through Ripton till we arrive within half a mile of the depression in the crest 

 of the Green Mountains, where the Hancock road crosses. Here, a little to the left of the 

 road, and 117 feet below its summit, we find embossed ledges of rock on which are two 

 very distinct sets of striae, the one running S. 50 E. pointing toward the depressed por- 

 tion of the mountain crest, with the stoss side on the northwest ; the other set pointing 

 W. 30 S. or down the valley, with the stoss side on the northeast. Hence the two sets cross 

 each other at an angle of 70, or more properly speaking their direction differs 110, the 

 force by which the first set was made pointing S. 50 E. and the other S. 60 W. The 

 force by which the first set was produced was up hill towards the crest of the mountain, 

 which a few miles to the north of the road we judge, without measurement, to rise 800 to 



