NAPLES STANDISH SERIES. 243 



basin of the lake is somewhat triaug-ular, and the ice would naturally con- 

 verge toward the narrow end at the south. The unusually deep mass of 

 glacial gravel south of the lake is probably in part a sort of terminal 

 moraine formed at the end of the tongue of ice which occu^jied the basin 

 of the lake. A small movement over the broad part of the basin and its 

 tributary valleys would cause a much larger flow at the extremity, where it 

 was only a mile wide. This would naturally cause a convergence of the 

 flow of the ice, and also of the glacial rivers to this place, and during the 

 retreat of the ice the deposition of a deep sheet of morainal matter. But 

 there is no unmodified till in sight near the south end of the lake, and 

 apparently the till last deposited has been entirely acted on by the glacial 

 water's so as now to be a part of the plexus of reticulated ridges of coarse 

 gravel, bowlderets, and bowlders that fill the valley. This makes the 

 deposit approach in character the overwash or frontal plains of gravel which 

 extend southward from the terminal moraines of the continental glacier. 

 Ice movements probably converged more than the average depth of 

 morainal matter here, where it Avas acted on by the subglacial rivers. 



Within a half mile from the south end of the lake the gravel of the 

 plains just described becomes finer, and within 2 miles it gradually jDasses 

 into sand, and finally into clay not far from the contour of 230 feet. A 

 line of sedimentary clays extends from the sea nearly to the lake, and 30 

 or more feet above the contour of 230 feet. At the north it borders the 

 southern part of the gravel and sand plain, both terminally and laterall}'. 

 The conditions of its deposition are uncertain. The gravel plain appears 

 to be a marine delta at its southern extremity. 



From the foot of Sebago Lake a discontinuous series of broad, table- 

 like ridges extends southward through the western part of Gorham, and 

 thence by a rather meandering course to near Buxton Post-Office, where it 

 seems to end in a delta (probably marine), a mile or more in length. The 

 intervals between the successive deposits are usually less than one-fourth 

 of a mile, but toward the noi-th they are somewhat larger. The gravel 

 plains are from an eighth to a half mile in diameter, and often foi'm some- 

 what rounded caps on the tops of hills, especially those not far south of 

 Sebago Lake. This series lies in a region wholly covered by the marine 

 clay, unless the clay near Sebago Lake be an exception. Perhaps the 

 whole series ought to be named the Naples-Buxton series. The gravels in 



