MOOSEHBAD LAKE OSAR. 125 



tain a swift current in the broader channel. Clay was then laid down on 

 the flanks of the previously formed osar-plain — osar border clay. 



In places the sea waves have washed down some of the top of the osar 

 and strewn the gravel over the adjoining clay. This osar is nowhere very 

 hig'h, and it does not spread out into broad plains, like many of the 

 systems, yet it is so continuous north of Veazie that it contains a large 

 amount of gravel. The meanderings of this osar do not in general depend 

 on any very evident surface features of the laud. 



Its length is about 60 miles, from Hampden north. 



MOOSEHEAD LAKE OSAR. 



This appears to be the longest tributary of the system. It is uncer- 

 tain how far a ridge of glacial gravel extends in the floor of Moosehead 

 Lake. G-ravel, probably glacial, appears on Hogback and Sandbar islands 

 in the midst of the lake. An osar appears on the western shore about 3 

 miles north of the so-called Southwest Cove of the lake. It follows the 

 west shore to the foot of the lake in Greenville, and thence runs southward 

 in a nearly straight course over a low divide in Shirley. Frona Shirley 

 northward the ridge is quite continuous, but while following the Piscataquis 

 Valley in Blanchard and Abbott on a down slope of about 50 feet per mile 

 the gravel is much interrupted for several miles, jaartly by recent erosion. 

 Near the north line of Abbott a plain of sand and gravel, now much eroded, 

 appears in the midst of the valley. A two-sided ridge extends for some 

 distance near Upper Abbott, but its summit has nearly the same level as 

 terraces which border both sides of the valley. This appears to be a ridge 

 of erosion, though it may have along its axis a core of coarser matter than 

 is contained in most of the plain. The stones of the ridge and terraces are 

 well rounded, like those of the glacial gravels, but, on the other hand, the 

 gravel extends from side to side of the valley, like river alluvium. This 

 condition prevails for several miles in Abbott. Much of this sand and 

 gravel is glacial, but the broad alluvial ridges and terraces of the Piscataquis 

 Valley in Abbott present a complex problem. Part of it seems to be an 

 osar-plain, part is a frontal delta, part of it may have been deposited in a 

 glacial lake, and in part it is composed of river drift. The very 'round 

 -shapes of the stones of what appears to be valley drift may best be 

 accounted for as an incident in the final melting: and retreat of the ice. If 



