112 Characters of loose materials formed by Glacial Action. 



places, — and this is the most common case, where the lines 

 diverge slightly, following, however, generally one main direc- 

 tion, which is crossed by fewer lines, forming more open 

 angles. These differences, no doubt, indicate various oscilla- 

 tions in the movement of the mass which produced the lines, 

 and shew probably its successive action, with more or less 

 intensity, upon the same point at successive periods, in ac- 

 cordance with the direction of the moving force at each inter- 

 val. The same variations within precisely the same limits 

 may be noticed in our day on the margin of the glaciers pro- 

 duced by the increase or diminution of the bulk of their mass, 

 and the changes on the rate of their movement. 



The loose materials which produced, in their onward 

 movement under the pressure of ice, such polishing and 

 grooving, consisted of various-sized boulders, pebbles, and 

 gravels, down to the most minute sand and loamy powder. 

 Accumulations of such materials are found everywhere upon 

 these smooth surfaces, and in their arrangement they present 

 everywhere the most striking contrast when compared with 

 deposits accumulated under the agency of water. Indeed, 

 we nowhere find this glacial drift regularly stratified, being 

 every where irregular accumulations of loose materials, scat- 

 tered at random without selection, the coarsest and most 

 minute particles being piled irregularly in larger or smaller 

 heaps, the greatest boulders standing sometimes uppermost, 

 or in the centre, or in any position among smaller pebbles 

 and impalpable powder. 



And these materials themselves are scratched, polished 

 and furrowed, and the scratches and furrows are rectilinear 

 as upon the rocks in situ underneath, not bruised simply, as 

 the loose materials carried onward by currents or driven 

 against the shores by the tides, but regularly scratched, as 

 fragments of hard materials would be if they had been fasten- 

 ed during their friction against each other, just as we observe 

 them upon the lower surface of glaciers where all the loose 

 materials are set in ice, as stones in their setting are pressed 

 and rubbed against underlying rocks. But the setting here 

 being simply ice, these loose materials, fast at one time and 

 moveable another, and fixed and loosened again, have rubbed 



