2IO FREDERICK G. CLAPP 



tance outside the map, and were apparently the only main streams 

 draining the triangular area which they include. 



THE NEEDHAM-FRAMINGHAM SYSTEM OF PLAINS. 



For convenience of discussion this designation is applied to the 

 group of plains lying between Needham and Framingham, having, 

 in addition to a common elevation of approximately 170 feet, most 

 of the characteristics of the preceding group. These deposits cover 

 an area beside which the Newtonville-West Roxbury area appears 

 insignificant; yet, as the writer has had little opportunity to study 

 them in detail, they will be dismissed with a few remarks. Belong- 

 ing to the group are at least six plains — the Framingham, Cochit- 

 uate, Pickerel Pond, North Wellesley, and Needham plains. All 

 have good ice-contact slopes, most of them on certain sides only; 

 but one plain, that lying east of Pickerel Pond between Wellesley 

 and Cochituate, is entirely surrounded by characteristic steep and 

 kettled slopes. This plain, like that forming Cow Island, is the 

 only member of its group not resting against the rock sides of the 

 valley, and, like Cow Island, is supposed to overlie a buried pre- 

 glacial gorge. 



The most conspicuous topographic characteristic of this region is 

 the abundance of kettle-holes, often occupied by ponds. Lake 

 Cochituate, Dudley, Pickerel, Mud, Jennings', and Morse's ponds 

 and Lake Waban are all kettle-ponds, overlying the course of the 

 preglacial Charles River. Between, around, and upon the ice- 

 blocks gravels were deposited, their mode of origin being demon- 

 strated by their kettled character. The proportionate area of kames 

 to kettles is much larger than in the deposits farther east, and the 

 kettles are more isolated. Plains having in general the same eleva- 

 tion extend far down the valleys of the Sudbury and Concord Rivers ; 

 thus emphasizing the suggestion that in the Sudbury valley there were 

 at that time fairly open bodies of water. 



Needham plain. — This is the largest and most typical plain in 

 the group. Hemmed in on east and west by rock hills, it is bounded 

 on the north by a deep preglacial valley, in which the ice lingered 

 and gave rise to deep kettles, extensive moraine-terraces, kames, and 

 eskers. Three or more eskers, with relations suggesting a super- 

 glacial mode of origin, enter the plain from the north. Its southern 



