Geological Papers. 97 



weight down to the finest rock-flour. The corrosion of these 

 boulders is of the glacial type, and examples presenting pol- 

 ished and striated faces abound. 



SUPERGLACIAL STREAMS. — These are streams that run over 

 the top of the glacier. They are of importance, because they 

 may carry large amounts of sediment onto the glacier and 

 deposit it. 



DEPOSITS OF SUPERGLACIAL STREAMS. 



Marginal Deposits. — Under this class are embraced all 

 the deposits of glacial streams that were made at the margin 

 of the "mer de glace," and whose forms were dependent upon 

 conditions that obtained at the margin of the ice-field. 



SUPERGLACIAL OSARS (ASARS) OR ESKARS (KAMES OF SOME 



authors). — These are channel deposits which have retained 

 their original elongated form and become ridges, and hence 

 fall under the Scandinavian type. They were left (dropped) 

 at the melting of the ice. 



SUPERGLACIAL Kames. — These were sheets or pockets of as- 

 sorted material gathered on the surface of the ice and doubt- 

 less subjected to much disturbance and rearrangement in the 

 process of descent at the melting of the ice-sheet. They now 

 constitute undulatory tracts of drift or groups of hillocks 

 scattered here and there over the glaciated region. 



Kames. — Kames are conical hills of discordantly stratified 

 sand and gravel, formed as such by glacial deposition, gener- 

 ally in a system transverse to the glacial movement. They 

 occur chiefly as components of terminal moraines. To use 

 the words of Geikie, "seen from a dominant point ... an 

 assemblage of kames . . . looks like a tumbled sea." 

 They are irregular heapings of assorted material, found along 

 the border tracts, and also distributed over the entire area 

 abandoned by the ice. They appear to be the products of 

 relatively active, vigorous glaciers. They resemble osars in 

 many respects, but differ from them in that they are trans- 

 verse to the glacial movement. 



OsAR (EsKAR) Deltas or Fans. — When the glacial streams 

 reached the border of the ice-sheet and were free from bound- 

 ing ice-walls, they spread themselves out widely and dropped 

 a large portion of their load in the form of deltas or fans, 

 hence the name overwash aprons. 



Overwash Apron Deposits. — Glacial overwash is the de- 



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