100 



BULLETIN OF THR ESSRX INSTITUTE. 



that the observations of Russell on the Malaspiiui glacier 

 fountains may afford an explanation of this case, for if 

 the subglacial drainage found its way to the surface of 

 the margin of the ice through a crevasse or hole when the 

 lower end of the subglacial streamway became clogged, 

 a break in the continuity of the esker-fan and the esker 

 would be expected. 



The Newtonville- Woodland wash-plains. — The Newton- 

 ville erfker-fan described by Professor Davis and modelled 

 by Dr. Gulliver lies south of the 

 Charles River apparently in line with 

 larger wash-plains lying between 

 Woodland and Wal)an stations on the 

 went. The Woodland plains are com- 

 plex in structure, showing the phe- 

 nomena of ice-retreat and the over- 

 lapping of newer plains on those 



Fig. 5. The Mechanics 



vi]le wash-plain with the pi-gyiously laid doWll 

 esker-like deposit nortli of ^ '' 



it. The " notch " between 

 the esker and the plain 

 is followed by a stream 

 and is occupied by a pond. 

 (Topography from Frank- 

 lin atlas sheet, U. S. Geol. 

 Survey.) 



Southeast of VVaban station stands 

 a ridge of gravel and sand with an 

 ice-contact slope on its northwestern 

 face with typical coarse detritus in the 

 contact zone. The opposite side of 

 the ridge is lower, slightly lobate, and the detritus finer. 

 The inclined surface of the deposit suggests that we have 

 in this case an alluvial cone built at the ice edge. The 

 deposit is lengthened parallel with the ice contact. 



The Cambridge moraine and plain. — Old Cambridge 

 lies upon a plain of sand whose northern limit is a well 

 defined ridge extending from Porter's Station southwest- 

 wards by the Harvard Ol^servatory and thence westwards 

 along the southern border of Fresh Pond to the Water- 

 town line. 



This ridge rises at three points to the uniform height 



