120 LABRADOR 



unbroken rock to form the post-Glacial landscapes. 

 Where the pre-Glacial cover of decayed rock was spe- 

 cially deep, a trough or a rock-basin remained after 

 the ice melted away. In this way the old valleys were 

 irregularly deepened and new depressions were sunk; 

 innumerable lakes and ponds were formed which to-day 

 make the peninsula one of the great lake-districts of 

 the world ; and the coastal belt assumed its present aspect 

 of singular raggedness. The diversity of relief in southern 

 Labrador is nowhere more conspicuous than along the 

 shore. When the ice finally disappeared, from mainland 

 and invaded sea-floor, the ocean waters entered the maze 

 of scoured troughs that open seaward. The ponderous 

 flood of ice was replaced by the restless sea, flooding a 

 perfect labyrinth of channels, straits, broad sounds, islands, 

 skerries, and headlands. 



There is evidence, too, to show that the solid, fresh rock 

 itself was attacked by the overriding ice. All rock is 

 intersected by more or less abundant cracks or planes of 

 weakness which divide it into blocks that may be rifted 

 away. Just as the quarryman uses these rifting planes to 

 remove slabs of marble, granite, or schist, so the Labrador 

 glacier with the wedge of the frost, with bottom friction 

 and shear, plucked out and carried off great blocks from 

 its firm, unweathered floor. The photograph of the 

 " ice-worn surface near Aillik Bay " illustrates a single 

 example of this process which had an important share 

 in the glacial remodelling of the topography. In the 

 view, the smooth slope on the left represents the 

 heavily scoured bed of the ice-sheet as it moved sea- 

 ward from right to left. The pond fills a small rock- 



