ALBANY-SAGO EIVEE SERIES. 251 



Waterford to Papoose Pond is very great, and shows that the g-ravels of 

 the osar-plain have been subjected to much more attrition. Going south- 

 ward in the valley, the lower layer of the valley drift becomes clayey. It 

 is overlain by sand containing some angular gravel — mere tillstones which 

 are scarcely polished. The plain of valley drift rises 20 to 30 feet above 

 the present bed of the river, which is bordered by two and sometimes three 

 terraces of erosion. At Edes Falls, in Otisfield, the nnderclay is overlain 

 by several feet of subangular gravel, sufficiently worn to suggest glacial 

 origin. Perhaps there are local kames somewhere in the midst of the val- 

 ley and part of the gravel was washed away by river floods and spi'ead 

 over the previously deposited nnderclay. No kames appeared near this 

 place in the banks of the river, but they may be situated near by and are 

 now hid by the valley drift. South of Edes Falls the plain of valley drift 

 is in general from a half mile to more than a mile in breadth. The lower 

 stratum is clay, while the upper is a thick layer of sand, which in many 

 places has blown into low dunes. For several miles north of Sebago Lake 

 the upper and lower layers of the valley alluvium have about the same 

 composition, and both are a fine silty sand. As stated elsewhere, the river 

 here has eroded a chaimel bordered by steep cliffs of silt, and there are no 

 higher erosion terraces, i. e., the rates of erosion and deposition are here 

 substantially equal. The upper end of the original basin of Sebago Lake 

 has been silted up for 2 or 3 miles, aiid perhaps farther. The Crooked 

 River unites with the outlet of Long Pond to form the Songo, which mean- 

 ders back and forth in a remarkable manner. This stream has been 

 celebrated by Longfellow in his song of "The Songo River." 



We thus see that true osar-ridges extend from Albany down the 

 Crooked River Valley to North Waterford. Then for several miles the 

 valley contains a plain of gravel, with cobbles and bowlderets too large 

 and too round to be a part of the valley drift, and ending in a broader 

 plain showing some of the characteristics of a delta, but not such a delta 

 as should form at the end of such a large glacial river as flowed through 

 Albany to North Waterford. Then for many miles, to Sebago Lake, there 

 is nothing in the valley that resembles the drift of the upper valley or that 

 can be considered as glacial gravel proper, unless it be a short deposit near 

 Edes Falls. That a large glacial river should end in that small plain at 



