198 GLACIAL GRAVELS OF MAINE. 



out in the field the hmits of the glacial, fluviatile, and estuarine drift of this 

 region, and to write out its full glacial and postglacial history. 



Androscoggin Pond, in Wayne, furnishes an interesting study. To 

 the west of it is situated the clay plain (overlain by, sand) bordering both 

 the osar and the Androscoggin Eiver. The pond is so nearly on a level 

 M'ith the river that its outlet is called the Dead Eiver. In time of flood 

 the water of the Androscoggin River is higher than the pond, and the flood 

 rushes with violence southeastward into the lake, carrying so much sedi- 

 ment that a large delta has been formed on the western shore of the pond. 

 Such an overflow into the pond would be much more vigorous directly 

 after the melting of the ice in the valley, when the Androscoggin River 

 stood at least as high as the top of the clay plain about 50 feet above its 

 present level. Under these conditions, why was there not a much larger 

 delta formed on the western shore of the lake*? Or, rather, why did not 

 the whole soutli end of the pond fill up"? It could not have been from lack 

 of sediment, for these same waters covered many square miles to the soutli 

 of this point with from 20 to 60 feet of clay and sand. But it is possible 

 that the depression where the pond now is was originally so deep a rock 

 basin that even a sheet of clay as deep as the plain of the Androscoggin 

 River could not fill it up. I have not examined all parts of the shore of 

 this large pond (it is about 5 miles long and 3 or 4 miles broad), but at 

 several points I did not find evidence that there had been deposition to such 

 a depth. A broad, open valley extends from Androscoggin Pond north- 

 ward through Wayne and Fayette into Mount Vernon and Vienna. In 

 late glacial time there would be a flow of ice down this valley for some 

 considerable time after the general ice movement had ceased. If this flow 

 was sufficiently rapid to replace the ice as fast as it was melted at the east- 

 ern margin of the osar channel or afterwards by the waters of the swollen 

 Androscoggin River or the sea, the place whei*e the pond now is may have 

 been covered by ice during the time of most active sedimentation. This 

 will account very plausibly for the fact that the pond did not fill up. 

 According to the late Hon. J. S. Berry, of Wayne, the greatest depth of 

 the lake is about 60 feet, and over most of the lake it is much less. 



A nearly north-and-south ridge of glacial gravel is found a short dis- 

 tance west of Leeds Junction. It ends at the south in a series of short 

 ridges separated by intervals. This series is about a mile in length. At 



