o, when the coast-ice is packed
into dense masses. Both the large and small stones thus conveyed usually
travel in one direction like shingle-beaches, and this was observed to
take place on the coast of Labrador and Gulf of St. Lawrence, between
the latitudes 50 degrees and 60 degrees N., by Capt. Bayfield, during
his late survey. The line of coast alluded to is strewed over for a
distance of 700 miles with ice-borne boulders, often 6 feet in diameter,
which are for the most part on their way from north to south, or in the
direction of the prevailing current. Some points on this coast have been
observed to be occasionally deserted, and then again at another season
thickly bestrewed with erratics.

[Illustration: Fig. 19.

Boulders, chiefly of granite, stranded by ice on the coast of Labrador,
between lat. 50 degrees and 60 degrees N. (Lieut. Bowen, R. N.)]

The accompanying drawing (fig. 19), for which I am indebted to Lieut.
Bowen, R. N., represents the ordinary appearance of the Labrador coast,
between the latitudes of 50 degrees and 60 degrees N. Countless blocks,
chiefly granitic, and of various sizes, are seen lying between high and
low-water mark. Capt. Bayfield saw similar masses carried by ice through
the Straits of Belle Isle, between Newfoundland and the American
continent, which he conceives may have travelled in the course of years
from Baffin's Bay, a distance which may be compared in our hemisphere to
the drifting of erratics from Lapland and Iceland as far south as
Germany, France, and England.

It may be asked in what manner have these blocks been originally
detached? We may answer that some have fallen from precipitous cliffs,
others have been lifted up from the bottom of the sea, adhering by their
tops to the ice, while others have been brought down by rivers and
glaciers.

The erratics of North America are sometimes angular, but most of them
have been rounded either by friction or decomposition. The granite of
Canada, as before remarked (p. 221 ), has a tendency to concentric
exfoliation, and scales off in spheroidal coats when exposed to the
spray of the sea during severe frosts. The range of the thermometer in
that country usually exceeds, in the course of the year, 100 degrees, and
sometimes 120 degrees F.; and, to prevent the granite used in the
buildings of Quebec from peeling off in winter, it is necessary to oil
and paint the squared stones.

In parts of the Baltic, such as the Gulf of B