234 GLAOIAL GRAVELS OP MAINE. 



able to trace the gravels. This makes it probable that not much if any 

 overflow took place from Lockes Mills eastward after the ice had become 

 melted west and northwest of Bryants Pond. 



A short line of g-lacial gravels comes from the north and joins the 

 South Bethel series near Lockes Mills. There are some signs that this 

 series extended northward across the middle intervale of the Androscoggin 

 in Bethel as an osar-plain, and then up the valley of Bear River toward 

 Umbagog Lake. I have not been able to find time for a careful explora- 

 tion of the route, and provisionally mai'k this gravel series as extending 

 only about a mile north from Lockes Mills. 



It has already been noted that there may have been an overflow from 

 the direction of Umbagog Lake to Andover, and that possibly a branch of 

 the Portland system followed the valley of the west branch of the Ellis 

 River. 



GENERAL NOTE ON THE PORTLAND SYSTEM. 



Three times this system of giacial gravels goes up a valley of natural 

 ■drainage to its source and crosses hills into other valleys, but it does not 

 cross hills higher than 150 feet. In order to penetrate the high hills by so 

 low passes, it makes some remarkable deflections in its course. At Oxford 

 there was in front of it a very low pass southward (along Thompson Pond), 

 but it took a higher pass southeastward tln-ough Poland, following a course 

 more neai'ly parallel to the glacial strife than was the other. The system 

 takes the form of an osar or osar-plain for most of the way north of the 

 Gray-New Grloucester marine delta. South of that point it is constantly 

 discontinuous, i. e., it consists of a series of plains or broad ridges sepa- 

 rated by intervals from a half mile up to 3 or 4 miles. In this part of its 

 course the gravels appear on the tops of Ioav hills or along the eastern bases 

 of such high hills as Walnut Hill and Black Strap Mountain. The plain 

 at Oak Hill in Scarboro, Stevens Plain in Leering, the plain at "West 

 Cumberland Fair-ground, and the other plain west of it in Cumberland 

 and Falmouth, also a large part of the Cray-New Gloucester plains, I con- 

 sider as marine deltas. The last named are by far the largest of these, and 

 are situated at an elevation of 200 to 230 feet. Several others of these 

 plains are deltas of some kind, hut I am not certain whether they were 

 ■deposited in the sea or in glacial lakes. Several of these deposits show 

 ■some but not all of the characters of deltas. Their material is so coarse. 



