GEOLOGY AND SCENERY OF NORTHEAST COAST 121 



basin produced by the glacial plucking away of many 

 blocks of the fresh rock (gneiss) frozen into the ice, and so 

 lifted and freighted off by the moving glacier. In the face 

 of the low cliff can be discerned the planes of rifting and 

 the outlines of several blocks that were in the very act of 

 being plucked away as the ice disappeared from the country. 

 It is an instructive case of natural quarrying. Ten thou- 

 sand other examples on the coast would show quite as 

 clearly that a glacier works with crowbar and crane as 

 well as with gouge and chisel. Using all its powers, the 

 ice-cap strongly modified the details of relief on the plateau 

 of southern Labrador. 



In so reaching a principal conclusion from the glacial 

 studies, let it not be forgotten that normal stream-cutting 

 in pre-Glacial times produced the grand features of the 

 sculpture. 



The energy of glacial attack is manifested not alone in the 

 remodelling of plateau and valley ; its power leaves enduring 

 records on the single ledge of rock. Observations on the 

 living glaciers of the world show that they scour their beds 

 not so much by the direct friction of ice against ledge as 

 by the dragging of frozen-in boulders over the bed-rock. 

 The pressure so applied is truly enormous. Deep grooves 

 or shallower "striae" running in the direction of ice-flow 

 are cut in the solid. rock by such "graving-tools." Lime- 

 stone, slate, trap, granite, or schist may be thus marked by 

 scratches, furrows, or channels from a fraction of an inch to 

 a foot or more in depth. They are not continuous mark- 

 ings, but occur only where the wearing boulder has been 

 pressed with irresistible might against the bare rock. 

 Shallow and deep striations of the sort are to be found on 



