484 



GLACIAL GRAVELS OF MAINE. 



several of the valleys. The list could have been considerably extended if 

 the elevations were known: 



Elevations of seashore in valleys of Maine. 



Name of valley. 



Place of highest admissible seashore. 



Character of deposit 



passing into marine 



fluviatile delta. 



Valley drift. 



Saco 



Presuiiipscot 



Little Androsoogg: 

 Twentymile River 



Androscoggin 



Sandy River 



Carrabassett 



Kennebec 



Standisli, below Steep Falls 



Near Sebago Lake 



. North Windham 



South Paris 



Sumner and Buckfield 



Livermore Falls, or Jay 



Farmington 



New Portland 



Bingham or Moscow 



200 to 250 

 250 to 260 

 250+ 

 400 

 350? 

 375+ 

 440+ 

 450? 

 450 to 500 



The Kennebec, because it occupies a deep depression and penetrates 

 far north and west, is better situated than any other of the valleys for con- 

 taining high-level marine beds. It presents many difficult questions of 

 interpretation which it will require detailed study to solve. The sands and 

 clays admitted as possibly marine in the above table have heretofore been 

 interpreted by me as valley drift laid down at the sides of a broadening 

 osar. The history of this interesting, because difficult, valley must largely 

 be left an open question. 



It has been before stated that the upper or rarely fossiliferous marine 

 clay passes up the valleys as the basal layer of what appears to be valley 

 drift. Even if we grant the highest elevations given above for the sea, we 

 do not reach the limits of the basal clay, which in places extends up to 600 

 feet or more. 



Probably the most important feature of the valley drift is that the 

 basal layer is of finer composition than the upper, at least until we reach 

 the steep mountain valleys. Sometimes it is a fine gray clay, at other times 

 a silt, but almost always it has a finer composition than the gravels and 

 sands that overlie it. This condition extends considerably below the old 

 sea level and is widely shown by beds undoubtedly marine. The valley 

 of the Penobscot River west from Medway shows little of the basal clay, 



