68 SURFACE GEOLOGY. 



the alluvial area. These are generally separated from the lower interval 

 by steep escarpments, which show that the difference in height is due to 

 excavation by the river. 



The only kames found in this area were several small irregular ridges 

 of coarse gravel at Woodland cemetery in Keene. The railroad cut north 

 of the bridge at South Keene shows successive layers of coarse gravel 

 and sand. These are 40 feet above the highest plains, being the delta 

 deposits of the branch which here enters the valley. South from this 

 station for one third of a mile we have irregular ridges 40 feet high at a 

 short distance west of the railroad, resembling kames in form, but scarcely 

 differing from common till. In the south part of Swanzey we find occa- 

 sional terraces, which are sometimes of coarse gravel, from 60 to 70 feet 

 above Great brook, showing that much material at first deposited here 

 was afterwards channelled out by this stream and carried northward to 

 the wide low plains. 



Modified Drift along the Pemigewasset and Merrimack River. 



The river which drains the central portion of New Hampshire has a 

 quite direct course slightly east of south. Its only departure in this 

 state from the general direction is between the villages of New Hampton 

 and Bristol, where it makes an offset of four miles to the west. This val- 

 ley affords one of the few avenues for crossing the mountainous region. 

 It begins in the deep gap of Franconia notch, between abrupt mountain 

 walls, and it is at first closely enclosed by the high ranges which extend 

 thence to the south. For twenty-five miles, or nearly to Plymouth, the 

 valley is singularly straight, as is well seen from the summits of Lafay- 

 ette and Cannon mountains, which rise at either side of its source; or it 

 forms a beautiful view from hills in Campton, with its fertile intervals and 

 well tilled farms extending for several miles, beyond which, at the end of 

 its long vista, are the serrated mountains cleft by the notch (vol. i, p. 551). 

 Its entire length from Profile lake, Franconia, to Massachusetts line, is 

 comparatively straight, forming a continuous line of depression, which is 

 a principal feature in the topography of the state. The upper and lower 

 portions of the river which occupies this valley are known by different 

 names. For more than fifty miles from its source this river is called 



