236 GLACIAL GRAVELS OF MAINE. 



gravel, cobbles, and larger stones found at short intervals in a strip onljr 

 about 100 feet wide. The rock, where un weathered, was very smooth, but 

 whether this was due to water polish or to the attrition of the glacier was. 

 uncertain. There was little till along the line of the glacial stream. Here, 

 then, was a rather small glacial stream that eroded the till and tumbled 

 over a steep cliff, yet did not erode a traceable channel in the solid rock or 

 form a pothole. The stones of the glacial gravel are all very much 

 rounded here, and must have been subjected to a large amount of rolling. 

 A plausible explanation of these facts lies in the hypothesis that the stream 

 was for a time occupied in eroding the till, and that it ceased to flow soon 

 after the rock had been laid bare. The gravels pass beneath the water at 

 the north end of Rattlesnake Pond and soon reappear on the western 

 shore. The glacial river followed this shore of the pond all the way to its- 

 south end. Between Eattlesnake and Panther ponds the glacial gravel 

 takes the form of an osar-plain. The gravel reappears near the south end 

 of Panther Pond, and continues as an osar-plain to Raymond Village. 

 Here, near Avhere the system crosses the outlet of Panther Pond, there is 

 apparently a short gap in the gravel plain. The plain soon begins again, 

 and continues its southwest coui'se till it reaches the shore of Sebago Lake, 

 when it turns south and follows the east shore of the lake for a half mile or 

 more. It rises 6 to 12 feet above the lake, and often ends at the lake in a 

 cliff of beach erosion. In all this part of its course the osar-plain continues- 

 an eighth of a mile in breadth, or in places a little broader. There was 

 nothing to hinder an ordinary stream having a southwest course fronL 

 sweeping its sediments out into the lake. The fact that there is no fan- 

 shaped delta at this point, though the stream that deposited the osar-plain 

 flowed at an elevation of several feet above the lake and was rapid enough 

 to transport cobbles and bowlderets, is conclusive proof that at the time the- 

 plain was being deposited the basin of Sebago Lake was covered by ice at 

 this point. 



The gravel plain soon leaves the shore of the lake and continues 

 southward over a pass 50 to 70 feet high to North Windham. In this part 

 of its course the system takes the form of a plexus of broad reticulated 

 ridges and hillocks, and it contains many kettleholes and hollows of all 

 sizes up to lake basins. Toward the south the plains spread out in fan. 

 shape and the rirlges become lower and gradually coalesce into a rather 



