f.'IO The American Geologist, February, 1891 
Arlington Heights. The drainage of the Nrponset and 
Charles basins thus eventually became tributary to lake 
Bouve atong^ the north side of the Blue hills, ;it the higlit. 
tirst, of the Glad Tidings plain, and. Later, of the Lower plain. 
Level tracts of modified drift at tli .-s ■• bights have an exten- 
sive development in the lower valleys of the Charles and 
Neponset rivers, and also in the upper valley of the Mystic 
river, outlining a body of standing water which it is proposed 
to call lake Shawmut, from the Indian name- for the original 
peninsula of Boston. 
The authors would also trace a relationship of the modified 
drift plains in the Concord and Shawsheen river basins with 
lakes Shawmut and Bouve. as formed in a more northern 
glacial lake tributary to these; but perhaps conditions of 
wholly fluvial drainage southeasterly toward Boston, while 
the ice-sheet still covered the lower part of the course of the 
Merrimac river east of Lowell and Lawrence, may have been 
adequate to give the large areas of modified drift stretching 
across Wilmington, Billerica, and Tewksbury, to Lowell. 
Excepting the glacial lake Contoocook, described by 
Upham eighteen years ago in the third volume of the Geology 
of New Hampshire, these lakes Bouve, Charles-Neponset, and 
Shawmut, are the first glacial lakes clearly defined and named 
in New England. 
