2o6 FREDERICK G. CLAPP 



the remaining three sides being free. Unhke the deltas already 

 described, this plain has no frontal lobes, being surrounded on the 

 north, west, and south by ice-contacts. Both to the south and west 

 are extensive areas of kames and moraine-terrace. 



Nahantan plain. — Lying a mile and a half southeast of Winchester 

 Hill, in the midst of a large kame field, is a plain having the same 

 approximate maximum elevation as the surrounding kames and of 

 the associated esker. In extent of isolation it goes a step beyond the 

 Winchester plain, as its surface does not rest at any point against 

 rock or till, and it is entirely surrounded by ice-contacts and kames. 

 As the slope of the Brookline highlands is not over i,ooo feet distant, 

 it is likely that rock exists only a short distance below the surface, and 

 the plain occupies as truly a marginal position as the others men- 

 tioned. In the area between this and the Winchester plain are two 

 eskers, which, while they have not been observed to run directly into 

 either plain, are supposed from their positions to mark the streams 

 which carried the water southward between the two lakelets. 



The esker running out of the Nahantan plain is better defined in 

 its relations than the ridges similarly situated with reference to the 

 preceding deposits. It quickly attains its individuality, and borders 

 the kame area for nearly half a mile before finally disappearing below 

 the Charles River meadows. One feature well worthy of special 

 note occurs just south of the plain, where there is an enlargement of 

 the esker barely 200 feet across, yet having all the characteristic 

 structural features of the larger plains. South of the terminus of 

 this esker the relations of the eskers of the series are not well defined. 

 Short ridges appear -above the flood-plain west and north of Cow 

 Island, and continue from near Spring Street southeastward, crossing 

 Washington Street on the boundary line between Boston and Dedham, 

 beyond which no attempt has been made to trace them. At the south- 

 ern point of Cow Island is a good junction of the main esker with a 

 ridge which crosses the river from the south. 



Cow Island, West Roxbtiry, and Dedham Island plains. — The 

 elevations of the first two of these are indicated by the map as about 

 10 feet lower than the other plains of the system. This discrepancy 

 may be real, but is more probably due to difficulty of interpreting the 

 contours on a map of the published scale. In either case, it is believed 



