62 SURFACE GEOLOGY. 



appear to have been formed at the disappearance of the ice-sheet, princi- 

 pally consisting of material contained in its mass and set free at its melt- 

 ing. Their origin was like that of the finer alluvium of the lowland 

 valleys ; and their date was at the end of the long period in which nearly 

 all our deposits of this kind were formed. 



Modified drift of similar character occurs upon the South Branch. At 

 the Crawford house, where several mountain torrents fall into the valley 

 and form this stream, a great depth of very coarse stratified detritus has 

 been brought down. This superficial deposit forms the water-shed be- 

 tween the Connecticut and the Saco, carrying it a third of a mile north- 

 west from the rocky summit of the pass, which is at the gate of the 

 Notch. 



A well marked series of kames, or ridges of very coarse gravel, extends 

 along the South Branch from about a mile north of the Crawford house 

 nearly to its mouth. It appears again on the north-east side of the Am- 

 monoosuc, between the mouth of this branch and the Fabyan house. 

 Here it forms a single steep, narrow ridge, from 30 to 40 feet high, 

 around which the river passes in a long southward bend. This ridge is 

 conspicuously seen from the railroads on the opposite side. The mound 

 known as the "Giant's grave," which was levelled down for the site of the 

 Fabyan house, was a similar ridge about 300 feet long. This was noticed 

 by Sir Charles Lyell, in his journey through the White mountains, who 

 says it presented "the same appearance as those mounds which are 

 termed 'osar' in Sweden."* Other deposits of the same kind lie between 

 this place and the White Mountain house, at the north edge of the allu- 

 vial area. This series of kames appears to have been formed by a glacial 

 river, which was fed from the melting ice-fields of the Mt. Washington 

 and Mt. Willey ranges. Similar kames, which were also formed by 

 glacial streams tributary to the Ammonoosuc valley, are seen along the 

 Cherry Mountain road south from its summit. 



That the ice of this area, near the end of the glacial period, moved west- 

 erly down this valley, is shown by abundant morainic boulders, which 

 have been transported from Mt. Deception to the Twin Mountain house, 

 where the glacier seems to have paused after its retreat from the lowlands 

 and the valley below. The kames which we have described mark its 



* Lyell's Second Visit to the United States. 



