[1. "Geological Sketches," p. 308.]

{p. 21}

ridges bear no resemblance whatever to the great drift-deposits of
the world, spread out in vast and nearly uniform sheets, without
stratification, over hills and plains alike.

And here is another perplexity: It might naturally be supposed that
the smoothed, scratched, and smashed appearance of the underlying
rocks was due to the rubbing and rolling of the stones under the ice
of the glaciers; but, strange to say, we find that--

"The scratched and polished rock-surfaces are by no means confined to
till-covered districts. They are met with _everywhere_ and _at all
levels_ throughout the country, from the sea-coast up to near the
tops of some of our higher mountains. The lower hill-ranges, such as
the Sidlaws, the Ochils, the Pentlands, the Kilbarchan and Paisley
Hills, and others, exhibit polished and smoothed rock-surfaces _on
their very crest_. Similar markings streak and score the rocks up to
a great height in the deep valleys of the Highlands."[1]

We can realize, in our imagination, the glacier of the
mountain-valley crushing and marking the bed in which it moves, or
even the plain on which it discharges itself; but it is impossible to
conceive of a glacier upon the bare top of a mountain, without walls
to restrain it or direct its flow, or higher ice accumulations to
feed it.

Again: