Then, too, during the day, the water made by melting finds its way into
the crevices, freezes, and hence expands, and, acting like a wedge,
forces the berg into fragments.

Much of the ice encountered at sea is discolored, and often full of dirt
and gravel, while not infrequently stones are found imbedded in it.

Along the shores of Labrador, where there is a large rise and fall in
the tide, ice is brought into contact with the bottom, and mud and
sea-weed are frozen in with it, while at times landslides precipitate
large quantities of dirt and stones on its surface.

As the ice leaves the coast and comes to the southward, it brings these
burdens with it, which are deposited on the ocean bottom when the ice
melts. As this melting occurs to a great extent over the Grand Banks, it
would seem that the deposit from the field ice would be greater than
that from bergs.

It is hard to understand why bergs should have foreign substances frozen
into them, as they are formed from snow deposited on the frozen surfaces
in the interior of Greenland, and hence their thickness is added to from
their upper surface.

It is possible that in their journey south in the Arctic current they
accumulate more or less foreign matter by having it ground into their
bottoms; but this does not seem probable, as it is hard to force gravel
into ice and give it a permanent hold, while mud accumulated in this way
would soon be washed out.