CARROLL MORAINE FIELD 283 



from ledges of the same composition as Mount Deception, unknown to 

 Hitchcock and Upham. Accordingly, when we reached this part of the 

 field, search was made on the wooded slope of the 2,060-foot hill immedi- 

 ately to the north of the blocks in question (see figure 1). A well con- 

 structed path which enters the woods at the Maine Central station and 

 runs to Cherry Mountain ascends this slope. For the first 300 or 400 feet 

 of vertical ascent one finds an abundance of boulders of the gray mussco- 

 vite-biotite granite, of the type known to Hitchcock as the "Mount Decep- 

 tion" granite. Coarse pegmatite veins, carrying much white mica, are 

 prominent in the rock, both here and in the blocks in the open fields east 

 of the Twin Mountain House. The granite varies noticeably in composi- 

 tion, especially as regards the amount of white mica. Near the 1,800- 

 foot contour the trail passes a particularly large angular boulder of it, 

 known as "Beechers Pulpit." Fifty yards farther up the slope and per- 

 haps 75 feet higher there is a ledge. The granite exposed there varies 

 from a gneissoid biotite granite on the one hand to a muscovite-biotite 

 granite on the other, the white mica appearing more conspicuously near 

 the pegmatite veins, possibly as a product of exomorphism. Here is the 

 same rock, in place, as that which composes the blocks reported by Hitch- 

 cock from the fields east of the Twin Mountain House, half a mile down 

 the hill. On the ledge a lump of quartz in one of the pegmatite veins 

 bears distinct striae in two places, which run south 27° east (corrected). 

 The map of glacial features in Hitchcock's atlas of New Hampshire shows 

 an arrow at this same place, as a sign that southeastward striae were ob- 

 served there. There is therefore every reason to suppose that the boulders 

 noted by Hitchcock moved southeastward a short distance from ledges on 

 this hillside during the passage of the Canadian ice-sheet, and not west- 

 ward four miles from Mount Deception on a local Ammonoosuc glacier. 

 Finally, it may be said that the stratified drift of the Carroll Twin 

 Mountain House district contains, besides the local granites and gneisses, 

 greenstones and chloritic schists from the "Huronian" belt of the Dalton 

 Range, which lies a mile or two northwest of it. So far as the esker near 

 the Twin Mountain House is concerned — a splendid example of its class — 

 its course is almost parallel to the striation and drift dispersion by south- 

 eastward-moving ice. All lines of evidence point to the conclusion that 

 it was built by a southward-flowing river rather than one which flowed 

 northward. 



CONCLUSIONS DRAWN FROM THE GLACIAL FEATURES OF. THE CARROLL 



DISTRICT 



In place of former theories, therefore, the following interpretation of 

 the features around Carroll and the Twin Mountain House is suggested: 



