MODIFIED DRIFT ALONG CONNECTICUT RIVER. 37 



vated by the river. The question which we see no satisfactory way to 

 answer is, How came tlie hollow which contains the pond to be formed 

 or left vacant, when the material of the otherwise nearly level plain was 

 deposited .-* Probably it marks the site of a mass of ice, broken from the 

 glacier, brought down by the flood, and finally stranded at this spot. The 

 principal objection to this hypothesis is the rapidity of deposition required. 



A large amount of modified drift has been brought down by Grant's 

 brook, forming the plain on which Lyme village is built. The common 

 has a slope of fifteen feet, and in a short distance farther east the same 

 deposit rises eighty feet more, to 635 feet above the sea, or 90 feet 

 higher than the water-shed between the village and Post pond. 



Ancient River-bed. In Norwich occurs the most interesting example 

 seen by us of a well-marked ancient river-bed high above its present 

 level. This extends two miles from Pompanoosuc river, one third mile 

 above its mouth, to the bend of Connecticut river a half mile south of 

 Tilden pond, which lies in a depression of this old channel. Its highest 

 point, from which there is a gradual descent both ways, is 520 feet above 

 the sea, or 145 feet above the river. West and south-west from this point 

 is a plain, from 30 to 40 feet higher; at the north-west the alluvium forms 

 a delta-like slope with no level top. South-west from Tilden pond the 

 original high plain has been excavated by springs and small streams to a 

 very irregular surface of hillocks and ridges. On the east side of this 

 ancient channel is the steep gravel kame, which for a while turned the 

 Pompanoosuc river in this course, till a direct passage was cut through 

 its ridge. 



Norwich village, 525 feet above the sea, is situated on a terrace-plain 

 of Bloody brook, which extends three fourths of a mile above the village, 



Ag. Coll. Delta of 

 farm. Mink Br. 



500. 564. 



, . , 350ft. 



above 



Fig. 7. — Section in Norwich and Hanover. Length, 3 miles. sea. 



rising 30 feet. At one mile south the modified drift on the Vermont side 

 is interrupted by a ledgy hill. 



Two miles north of Hanover the Connecticut river has cut through the 



