MODIFIED DRIFT ALONG LOWER AMMONOOSUC RIVER. 6$ 



diminishing extent at a later date. At both these dates great amounts 

 of alluvium were brought down by its streams, forming a wide interval 

 between the Fabyan house and the Lower falls, which fills what must at 

 first have been a deep lake basin, and spreading out at and below the 

 Twin Mountain house in an extensive low plain. The height of the 

 former is from 1,560 to 1,550, and of the latter from 1,375 to 1,350 feet 

 above the sea. Considerable deposits of modified drift occur at other 

 points along the upper portion of this valley. 



Below Littleton we find the alluvium continuous, and usually in large 

 amount on one or both sides of the river to its mouth. This is a distance 

 of nearly twenty miles, in which the river descends about 400 feet, having 

 its mouth 407 feet above the sea. The highest terraces near Littleton 

 are from 60 to 75 feet above the river, but scarcely any deposits occur for 

 the first five miles above the low terrace, which is partly interval. Below 

 North Lisbon both this and the high terrace, which sometimes widens 

 into plains, are well shown. South-west from North Lisbon the high 

 terrace is about 100 feet above the river; at Lisbon, about 125; at the 

 east line of Bath, 150; at Bath village, 175 ; and one mile from its mouth, 

 200 feet, or 220 on its south side and 225 on its north side above Con- 

 necticut river. The slope of the ancient high flood-plain of the Lower 

 Ammonoosuc was thus about 12 feet to a mile, descending but little more 

 than half as much as the present river. The only kame observed in this 

 lower part of its valley was a short ridge of gravel between the railroad 

 and highway at the east line of Bath. 



Modified Drift and Water-worn Rocks at Orange and Newbury 



Summits. 



The lowest point in New Hampshire, upon the water-shed which 

 divides the Connecticut and Merrimack basins, is at the summit of the 

 Northern Railroad in Orange. Two rock-cuts, each about 30 feet in 

 depth and together a quarter of a mile in length, were here made for the 

 passage of the railroad through ledges of gneiss. Both these excavations 

 were at the lowest points over which water could flow between these val- 

 leys. At the south excavation the top of the ledge on the east side 

 shows in a distance of about fifty feet three water-worn cavities, 4, 6, and 

 12 feet deep, in order from north to south, one half of each of which has 



