134 GLACIAL GRAVELS OF MAINE. 



JO MERRY OSAR. 



This osar is said to extend through the wilderness for about 10 miles 

 along- Pratt Brook, a stream which flows nearly east into the middle of Jo 

 Merry (or Jo Mary) Lake. Its course prolonged would lead it near South 

 Twin Lake, and it may be an extension of the Medford-Hampden osar. 



ROACH RIVER OSAR. 



Roach River flows westward into Moosehead Lake. An osar follows 

 the valley of this stream quite continuously for about 12 miles. Large 

 pebbles and cobbles, with some bowlderets, make up the larger part of the 

 ridge. The stones are not much rounded at the angles, though they plainly 

 have polished surfaces, an indication that the system does not extend much 

 farther to tliQ north or west. From the head waters of Roach River low 

 passes lead down the valleys of both the east and the middle branches of 

 Pleasant River. These two branches unite near the north line of Brown- 

 ville, and from near their junction a plain of sand and gravel containing 

 many very round pebbles and cobbles extends up botli valleys for about 

 3 miles northward. Here my exploration ended, and my information as to 

 the valleys above this point is indefinite and conflicting. The preponder- 

 ance of evidence favors the hypothesis that the principal glacial streams 

 flowed down the valley of the east branch of Pleasant River. It length is 

 about 25 miles. 



KATAHDIN IRON WORKS OSAR. 



A two-sided ridge from 15 to 30 feet high extends along the valley of 

 the west branch of Pleasant River for several miles above the Katahdin 

 Iron Works. Much well-rounded gravel is found along the valley below 

 this place in Williamsburg which resembles a delta in composition and 

 structure. The most probable theory as to its origin, according to my 

 present information, is that glacial rivers flowed down the A'alleys of all 

 three branches of the Pleasant River at a time when the valley of the main 

 river to the south was bare of ice. The well-rounded gravel was thus 

 brought down to the extremity of the ice and then spread as valley drift 

 over the open valleys. This is an interesting region and deserves further 

 study. 



A plain of well-rounded gravel more than 2 miles long and from one- 



