ads up to; and this early development was greatly helped by the flat
and fertile plain which follows it inland for over 600 m. from the city
of Quebec to Lake Huron. This affords the largest stretch of arable land
in eastern Canada, including the southern parts of Ontario and Quebec
with an area of some 38,000 sq. m. In Quebec the chief portion is south
of the St Lawrence on the low plain extending from Montreal to the
mountains of the "Eastern Townships," while in Ontario it extends from
the Archean on the north to the St Lawrence and Lakes Ontario, Erie and
Huron. The whole region is underlain by nearly horizontal and
undisturbed rocks of the Palaeozoic from the Devonian downward.
Superimposed on these rocks are Pleistocene boulder clay, and clay and
sand deposited in post-glacial lakes or an extension of the Gulf of St
Lawrence. Though petroleum and salt occur in the south-west peninsula of
Ontario, metalliferous deposits are wanting, and the real wealth of this
district lies in its soil and climate, which permit the growth of all
the products of temperate regions. Georgian Bay and the northern part of
Lake Huron with the whole northern margin of Lake Superior bathe the
foot of the Laurentian plateau, which rises directly from these lakes;
so that the older fertile lands of the country with their numerous
cities and largely-developed manufactures are cut off by an elevated,
rocky and mostly forest-covered tract of the Archean from the newer and
far more extensive farm lands of the west. For many years this southern
projection of the northern wilderness was spanned by only one railway,
and offered a serious hindrance to the development of the regions
beyond; but settlements are now spreading to the north and rapidly
filling up the gap between east and west.

_The Interior Continental Plain._--Passing westward by rail from the
forest-covered Archean with its rugged granite hills, the flat prairie
of Manitoba with its rich grasses and multitude of flowers comes as a
very striking contrast, introducing the Interior Continental plain in
its most typical development. This great plain runs north-westward
between the border of the Archean protaxis and the line of the Rocky
Mountains, including most of Manitoba, the southern part of Saskatchewan
and most of Alberta. At the international boundary in lat. 49 deg. it is
800 m. wide, but in lat. 56 deg. it has narrowed to 400 m. in width, and
to the north of lat. 62 deg. it is sti