WEST POLAlSfD STJMNER SYSTEM. 213 



The delta-plain northeast of Buckfield Village has been deeply eroded 

 by streams and springs. At one place a long ridge has been left uneroded. 

 It is locally known as the "Whalesback." On the sui-face it appears to be 

 composed of nearly horizontally stratified sand and gravel like the rest of 

 the delta, yet there must be some reason why this portion of the plain has 

 resisted erosion, and it may be there is a ridge of coarse kame stuff along 

 the axis of this "Whalesback." Evidently this delta dates from a late period, 

 when the ice had melted as far north as this place. 



The apparent end of this system northeast of Buckfield is only about 

 a mile from the West Sumner-Poland system. It is therefore possible — 

 perhaps probable — that they were at one time connected, but thus far I am 

 unable to prove it. The Peru glacial river may have joined that from West 

 Sumner by flowing southwest from the above-mentioned delta-plain through 

 Buckfield Village or along a very low valley situated about a mile farther 

 east. These valleys are all so deeply covered by sedimentary clay that 

 only large deposits of glacial gravel would rise above the surface. This 

 clay is probably of estuarine origin. 



The length of the system from AVorthley Pond to Buckfield is 13 miles. 



WEST SUMNER-POLAND SYSTEM. 



This system appears to begin about a mile south of West Sumner, in 

 the form of an osar-ridge which follows the valley of the west branch of 

 Twentymile River for several miles and then expands into a delta-plain a 

 short distance west of Buckfield Village. From this point a broad, low 

 valley extends southwai'd to Mechanic Falls. Along this valley the railroad 

 is constructed. The bottom of the valley is covered with sedimentary clay, 

 continuous on the north with the clay of the valley of Twentymile River 

 and on the south with that of the Little Androscoggin Valley. A series of 

 low ridges, terraces, and deposits of glacial gravel resembling the broad 

 osar is found along the valley its whole length. Near Buckfield the gravels 

 skirt the base of the high hills lying west of this valley, near East Hebron 

 they lie in the midst of the pass, and at West Minot they are on the west 

 side again. As we approach Mechanic Falls the gravels rise out of the 

 valley and are found on the slopes of the hills on the east side. There are 

 several apparent short gaps in the series. The intervals are more frequent 

 toward the south and the deposits become narrower and finally form simple 



