1 84 M. L. FULLER 



Relatively little is known as to the minor details of the rock topog- 

 raphy^within the basin, as the floor is deeply covered, except perhaps 

 in the center, with extensive planes of stratified drift, which rises in 

 places to nearly 150 feet above the marshy tracks along the main 

 streams, which in turn are of unknown, though probably not very 

 great, elevation above the rock-floors beneath them. The wells in 

 the region are generally shallow, and in most instances afford little 

 information'of value. The details of the plains and of the cols in the 

 rock-rim, many of which served as channels for the overflowing 

 waters, can be considered to the best advantage in the discussion of 

 the various stages in the history of the bed. 



STAGES OF DEPOSITION. 



The history of the Stoughton Bay area of Lake Neponset may be 

 said to have begun when the first body of water came into existence 

 between the ice and the retaining walls of the basin. Such a lake- 

 let must of necessity have been of small size at the beginning, but 

 soon became enlarged through the melting back of the ice. The 

 outlets may have been over low points in the rock-rim, or along the 

 edges of the ice. As the melting progressed, the expansion of the 

 lakelets continued until the lower outlets of the waters were uncov- 

 ered. 



The different levels of the waters are indicated approximately by 

 the altitude of the stratified deposits, which were laid down during 

 the different stages. In Stoughton Bay these deposits are of two 

 general levels, the higher standing at 250 feet, and the lower at about 

 190 or 200 feet above the level of the sea. The higher stage is named 

 from the town of Stoughton, the greater part of which is located on 

 the high-level deposits, while the lower stage is named from the 

 village of Springdale, near which the lower planes are strongly devel- 

 oped. 



The distribution of the materials show that not all the deposits, 

 even of a single stage, were laid down in the same body of water, 

 but accumulated, on the contrary, in more or less separate lakelets. 

 The principal water bodies of the higher stage were the Rattlesnake 

 Hill, East Sharon, and Stoughton lakelets, while the leading bodies 

 of the lower stage were the Elm and Springdale lakelets. 



