e Bay of Fundy,
Massachusetts Bay, Long Island Sound, and others. The unmistakable
traces of glacial action upon all the islands along the coast of New
England, sometimes lying at a very considerable distance from the
mainland, give an approximate, though a minimum, measure of the former
extent of the glacial drift seaward, and the subsequent advance of the
ocean upon the land. Like those of the harbor of Para, all these islands
have the same geological structure as the continent, and were evidently
continuous with it at some former period. All the rocky islands along
the coast of Maine and Massachusetts exhibit the glacial traces wherever
their surfaces are exposed by the washing away of the drift; and where
the drift remains, its character shows that it was once continuous from
one island to another, and from all the islands to the mainland.

It is difficult to determine with precision the ancient limit of the
glacial drift, but I think it can be shown that it connected the shoals
of Newfoundland with the continent; that Nantucket, Martha's Vineyard,
and Long Island made part of the mainland; that, in like manner, Nova
Scotia, including Sable Island, was united to the southern shore of New
Brunswick and Maine, and that the same sheet of drift extended thence to
Cape Cod, and stretched southward as far as Cape Hatteras;--in short,
that the line of shallow soundings along the whole coast of the United
States marks the former extent of glacial drift. The ocean has gradually
eaten its way into this deposit, and given its present outlines to the
continent. These denudations of the sea no doubt began as soon as the
breaking up of the ice exposed the drift to its invasion; in other
words, at a time when colossal glaciers still poured forth their load of
ice into the Atlantic, and fleets of icebergs, far larger and more
numerous than those now floated off from the Arctic seas, were launched
from the northeastern shore of the United States. Many such masses must
have stranded along the shore, and have left various signs of their
presence. In fact, the glacial phenomena of the United States and
elsewhere are due to two distinct periods: the first of these was the
glacial epoch proper, when the ice was a solid sheet; while to the
second belongs the breaking up of this epoch, with the gradual
disintegration and dispersion of the ice. We talk of the theory of
glaciers and the theory of icebergs in reference to these phenomena, as