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- 
