180 ULAUIAL GKAVELS OF .MAINE. 



of the river for about three-fourths of a mile^ The southern portion of 

 this ridge is so disguised by the sands and clays of tlie valley that it 

 is uncertain whether it ends in a delta-plain or not. 



The stones of the series are polished, but in general not so much so 

 as those of the long systems. A noticeable feature of this series is that 

 it is discontinuous at its northern extremity in the same way that the long 

 osars usually become discontinuous at their southern ends. 



The relation of this system to the osar border clay and the alluvium 

 of the Carrabassett Valley is interesting. The gravels at the southern 

 extremity of the series are more or less covered by the clay and sand 

 of the Kennebec Valley. Northward in the valley of the Carrabassett 

 the gravels are flanked by a plain of nearly horizontally stratified fine 

 sediments. This bordering plain is of varying breadth up to one-fourth 

 of a mile, and extends all the way to the Carrabassett Stream. Clay 

 and silty clay are most abundant in the border plain, but some layers 

 of sand alternate with the clay. The fact that this plain follows the course 

 of the glacial'stream up and over a divide, rising above the alluvial plain of 

 the Carrabassett Valley 20 or more feet by aneroid, proves that the clay 

 along the line of the kames was not due to an overflow of the Carra- 

 bassett River, but was deposited in a broad ice channel. Here and there 

 on the border plain of clay are bowlders 2 to 4 feet in diameter. They 

 have the shapes of the ordinary till bowlders, and were probably depos- 

 ited by floating ice. Near the line of the gravels 1^ miles south of 

 the Carrabassett, wells 30 feet deep do not reach the bottom of the 

 clay. At this point is an interesting feature of the osar border plain. 

 Toward the east it is continuous with and fully as high as the broad 

 plain of sand and clay which extends about 5 miles northeastward across 

 the Carrabassett River into Embden. But toward the west the clay 

 border plain slopes down rather steeply to a swamp, one-half mile or more 

 wide, which is about 20 feet lower than the plain itself A small brook 

 flows from the swamp northeastward across the sedimentary plain to the 

 Carrabassett, having eroded a deep and narrow ravine in it. This small 

 stream can not have eroded the clay over several hundred acres at the 

 swamp and only a narrow strip over the rest of the alluvial plain. On 

 the north side of the Carrabassett opposite this point there is a valley 

 extending back farther from the river than this, yet it is covered with 



