194 GLACIAL GKAVELS OF MAINE. 



leads from Wayne to Nortli Monmouth, and it rises 150 feet while crossing 

 the spur of the hill. Parallel with the road is a U-shaped ravine from 20 

 to 40 feet deep on the steeper slopes of the hill, but hardly perceptible for 

 a short distance near its top. The ravine is found on both the north and 

 south slopes. Till shows in the bottom of the ravine, and it is strewn with 

 many more bowlders — 2 to 4 feet in diameter — than appear in the fields of 

 till at each side. This fact indicates that this is a ravine of erosion. The 

 bottom of the ravine is rather level in cross section and is from 30 to 100 

 feet wide. This is an extraordinary amount of erosion in the till. But the 

 drainage slopes are only about a half mile long on each side of the hill, no 

 springs or streams appeared in the valley at the time of my examination, 

 and the bottom was wholly grassed over, except a small channel on the 

 southeastern slope eroded by the rains. Assuming that this canal-like- 

 depression Avith rather steep banks is the result of erosion, the rains and 

 shower streams do not seem competent for the work, judging from the 

 amount of erosion accomplished by the streams of this j^art of the State. 



Passing a short distance down the southeastern slope, we come to a 

 ridge of well-rounded glacial gravel whicli extends through the village of 

 North Monmouth and then becomes discontinuous. Two or three small 

 plains of gravel take us to the plain at the cemetery southeast of Mon- 

 mouth, already described. Here this tributary probably joined tlie main 

 river, and one or more of the northern sjjurs of that irregular plain may 

 have been deposited by it. 



It is thus proved that a glacial river flowed from the north to the base 

 of the southwestern spur of Mount Pisgah. The only trace of any con- 

 nection is found on' the southeastern side of this hill. It is thus made 

 highly probable that a glacial river flowed up and over this hill, 150 feet 

 high, along the line of that remarkable raA^ne. The great erosion, which 

 could not be accounted for b}^ the action of the' rains, thus becomes intelli- 

 gible. A glacial stream here eroded a large body of till, probably in con- 

 siderable measure a part of the ground moraine. Why did it not erode 

 the till at the top of the hill equally with that farther down its slope? 



The large size of the bowlders near the north end of the series favors the 

 hypothesis that this was a subglacial stream. There are some remarkable 

 heaps of till on the southern slopes of Mount Pisgah that deserve study. 



The lensrth of the branch is 7 miles. 



