OSARS. 415 



only solid that can have served this purpose. The osar rivers had tributary 

 and delta branches like those of ordinary rivers. While often following- 

 drainage slopes like surface rivers, yet more often they traversed rolling 

 plains or passed over hills from one drainage basin to another, thus freely 

 disregarding the minor inequalities of the land. In only a few cases did 

 they cross hills rising more than 200 feet above the valleys on the north. 

 They penetrate the hilly regions along low jDasses, and often take the form 

 of terraces far up on the hillsides. 



Several features of the osars require further discussion. The osars 

 proper are best developed in central and eastern Maine. The northern 

 parts of the longer ridges are rather small and narrow and have rather 

 steep lateral slopes. Standing on the narrow top, the meandering ridge 

 often presents an uneven, heaped appearance, much like a moraine. Going 

 southward, on the average the ridges become larger and have a more even 

 surface. When within about 75 miles of the coast, every few miles enlai-ge- 

 ments of the ridges are found which have various forms. Sometimes they 

 are little tables only 200 to 300 feet wide and two or three times as long. 

 These may be solid or may contain one or more shallow kettleholes. Here 

 and there a hummock aj^pears on top of the osar, rising 20 to 40 feet above 

 the rest of the ridge, and at these "pinnacles" the ridge is generally broader 

 than elsewhere. At one or two places within the belt of country lying 

 between 50 and 75 miles from the coast, we find the osar usually divides 

 into two or more ridges which after a time come together again and form a 

 single ridge. They thus inclose long, narrow basins, or, when connected 

 by cross ridges, rather deep kettleholes. These areas of reticulated ridges 

 are not large, a mile or two in length and hardly an eighth of a mile wide. 

 In this part of their coiirses several of the osars expand into broad, solid 

 plains or massives a mile or two long and nearly half as wide. Thus, in 

 Greenbush the Katahdin system twice expands into massives of this kind 

 rising about 100 feet above the rest of the osar and the level plain in 

 which they are situated. Their surfaces are rolling and afford some 

 shallow basins, but they can not be regarded as a plexus of reticulated 

 ridges in their present form. They are what such a plexus would become 

 if the inclosed basins were nearly filled up with gravel so as to leave only 

 shallow hollows. One of these massives thus represents a single broad 

 ridsre of uneven surface. 



