And this accords with what we know of the deposition of the Drift. It
came with terrific force. It smashed the rocks; it tore them up; it
rolled them over on one another; it drove its material _into_ the
underlying rocks; "it _indented it_ into them," says one authority,
already quoted.

It was accompanied by inconceivable winds--the hurricanes and
cyclones spoken of in many of the legends. Hence we find the loose
material of the original surface gathered up and carried into the
drift-material proper; hence the Drift is whirled about in the
wildest confusion. Hence it fell on the earth like a great snow-storm
driven by the wind. It drifted into all hollows; it was not so thick
on, or it was entirely absent from, the tops of hills; it formed
tails, precisely as snow does, on the leeward side of all
obstructions. Glacier-ice is slow and plastic,

{p. 98}

and folds around such impediments, and wears them away; the wind does
not. Compare the following representation of a well-known feature of
the Drift, called

###

CRAG AND TAIL.--_c_, crag; _t_, till.

"crag and tail," taken from Geikie's work,[1] with the drifts formed
by snow on the leeward side of fences or houses.