. long from north to south and 600 m. wide, with
its outlet Hudson Strait, has long been navigated by trading ships and
whalers, and may become a great outlet for the wheat of western Canada,
though closed by ice except for four months in the summer. Of the nine
provinces of Canada only three have no coast line on salt water,
Manitoba, Alberta and Saskatchewan, and the first may soon be extended
to Hudson Bay. Ontario has a seaboard only on Hudson Bay's southern
extension, James Bay, and there is no probability that the shallow
harbours of the latter bay will ever be of much importance for shipping,
though Churchill Harbour on the west side of Hudson Bay may become an
important grain port. What Ontario lacks in salt water navigation is,
however, made up by the busy traffic of the Great Lakes.

Geology.

The physical features of Canada are comparatively simple, and drawn on a
large scale, more than half of its surface sloping gently inwards
towards the shallow basin of Hudson Bay, with higher margins to the
south-east and south-west. In the main it is a broad trough, wider
towards the north than towards the south, and unsymmetrical, Hudson Bay
occupying much of its north-eastern part, while to the west broad plains
rise gradually to the foot-hills of the Rocky Mountains, the eastern
member of the Cordillera which follows the Pacific coast of America. The
physical geography of Canada is so closely bound up with its geology
that at least an outline of the geological factors involved in its
history is necessary to understand the present physiography. The
mountain structures originated in three great orogenic periods, the
earliest in the Archean, the second at the end of the Palaeozoic and the
third at the end of the Mesozoic. The Archean mountain chains, which
enclosed the present region of Hudson Bay, were so ancient that they had
already been worn down almost to a plain before the early Palaeozoic
sediments were laid down. This ruling geological and physical feature of
the North American continent has been named by E. Suess the "Canadian
Shield." Round it the Palaeozoic sands and clays, largely derived from
its own waste, were deposited as nearly horizontal beds, in many places
still almost undisturbed. Later the sediments lying to the south-east of
this "protaxis," or nucleus of the continent, were pushed against its
edge and raised into the Appalachian chain of mountains, which, however,
extends only a short distan