40 GLACIAL GEAVELS OF MAINE. 



rather than to any freak of sedimentation whereby no stratification was 

 produced. If the sediment was deposited upon the ice it would naturally 

 lose its structure during the melting of the subjacent ice. 



Shapes of the constituent fragments. — In tlic glacial gravcls WO fiud all dcgrccs of 

 water wear. In some of the shorter systems and toward the northern ends 

 of many of the longer systems the stones and grains are but barely pol- 

 ished at the angles and differ so little from till in their shapes that the mass 

 may be regarded as a slightly water-washed till. On the other hand, most 

 of the stones and grains of the kames and osars show a very large amount 

 of attrition and rolling and are very much rounded. 



Direction and distance of glacial-gravel transportation. In Small COneS aud domeS tho 



lines of lamination frequently dip outward in all directions, as if the water 

 came from above at the center of the cone and flowed downward and out- 

 ward on all sides. In the case of ridges, the frequency of transverse and 

 oblique dip shows that much of the drift was first at the top and center of 

 the ridge, and thence was washed partly lengthwise of the ridge and partly 

 sidewise or downward. At the fan-shaped delta localities, where glacial 

 streams flowed into broadened channels, or into glacial lakes, or the sea, 

 there were many local whirls and eddies where kame matter was transported 

 northward for short distances. With the exception of these accidents of 

 water motion within the tortuous channels of the glacial rivers or near their 

 mouths, the proof is in most cases conclusive that kame and osar transpor- 

 tation was southward. In a few places I have found no positive proof of 

 the direction of motion. The direction of flow is proved by the following 

 considerations: The prevailing southward dip of the laminje of the ridges; 

 the higher elevation at the north end of the systems ; the direction of the 

 flow of the glacier and the position of the terminal moraines; and directly 

 and positively by observations on the osar drift itself Where an osar passes 

 from an area of one kind of rock into an area of a different rock, the osar 

 drift changes just as the till does, but not so abruptly; it is thus proved that 

 the average distance of transportation was greater in the case of the osars 

 than in the case of the till, and also that the drift was in the same direction. 

 Proofs of this are given elsewhere. Naturally when one sees gravel sys- 

 tems going up the northern side of a hill to a height of 200 feet or more, 

 it seems incredible that a stream could flow southward over such a barrier. 

 That they actually flowed over such barriers is strong evidence of the 



