190 THE PHENOMENA OF DRIFT, OR 



5. Moraines. 



If the term moraine must be limited to those accumulations of 

 detritus which are produced by glaciers descending from moun- 

 tains, then it seems to me, that we have yet no evidence of the 

 existence of moraines in this country, except along the northern 

 ocean. But if we may embrace in the term those masses of drift 

 that have been produced by the stranding of icebergs, and by 

 their grating along the bottom, and perhaps by thek gyratory 

 motion, then, if I mistake not, otir country abounds with mo- 

 raines. I shall venture to use the term with this extended signi- 

 fication, in describing our drift. All the ridges and hills of gravel 

 which I call moraines, are evidently iceberg" moraines. 



The definition which I should give of an American moraine 

 is this : — a mass of detritus, more or less worn, that has been 

 transported, or crowded along, and piled up by drift ice. Such 

 a mode of formation would of course generally obliterate the 

 marks of stratification, if they ever existed in the transported 

 mass. But as water must have been concerned in crowding along 

 the ice, we might expect that its currents would sometimes act 

 on the finer part of the materials, and produce, it might be, lam- 

 ination and sn-atification in one part of a moraine, w^hile the 

 greater part of it was destitute of parallel arrangement. Again, 

 the drift ice might sometimes crowd along a previously stratified 

 deposit to a considerable distance, without destroying entkely the 

 bedding and lamination. Now the fact is, that what I call mo- 

 raines, con-espond to these suppositions. The most remarkable 

 of them are entirely unstratified. In others we see occasional 

 traces of a sorting and parallel arrangement of the ingi'cdients, 

 strangely mixed up with the unarranged mass. This fact always 

 appeared to mo entirely inexplicable, till the joint action of ice and 

 water was suggested as the cause. There are other cases, in which 

 I suspect that a deposit of laminated clay was crowded along, 

 e?i masse, and left in the midst of rounded and unstratified mate- 

 rials. As an example, I would refer to PI. VIII, f. 7, representing 

 the north bank of a deep excavation on the rail-road in Palmer, 



