visible in the rocks of Scandinavia, Scotland,
Canada, and many other countries.

There can be no doubt that the myriads of angular and rounded blocks
above alluded to, cannot have been borne along by ordinary rivers or
marine currents, so great is their volume and weight, and so clear are
the signs, in many places, of time having been occupied in their
successive deposition; for they are often distributed at various depths
through heaps of regularly stratified sand and gravel. No waves of the
sea raised by earthquakes, nor the bursting of lakes dammed up for a
time by landslips or by avalanches of snow, can account for the observed
facts; but I shall endeavor to show, in the next book, chap. 15,[236]
that a combination of existing causes may have conveyed erratics into
their present situations.

The causes which will be referred to are, first, the carrying power of
ice, combined with that of running water; and second, the upward
movement of the bed of the sea, converting it gradually into land.
Without entering at present into any details respecting these causes, I
may mention that the transportation of blocks by ice is now
simultaneously in progress in the cold and temperate latitudes, both of
the northern and southern hemisphere, as, for example, on the coasts of
Canada and Gulf of St. Lawrence, and also in Chili, Patagonia, and the
island of South Georgia. In those regions the uneven bed of the ocean is
becoming strewed over with ice-drifted fragments, which have either
stranded on shoals, or been dropped in deep water by melting bergs. The
entanglement of boulders in drift-ice will also be shown to occur
annually in North America, and these stones, when firmly frozen into
ice, wander year after year from Labrador to the St. Lawrence, and reach
points of the western hemisphere farther south than any part of Great
Britain.

The general absence of erratics in the warmer parts of the equatorial
regions of Asia, Africa, and America, confirms the same views. As to the
polishing and grooving of hard rocks, it has lately been ascertained
that glaciers give rise to these effects when pushing forward sand,
pebbles, and rocky fragments, and causing them to grate along the
bottom. Nor can there be any reasonable doubt that icebergs, when they
run aground on the floor of the ocean, must imprint similar marks upon
it.

It is unnecessary, therefore, to refer to deluges, or even to speculate
on the former existence of a clima