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AMERICA [north dwelt upon because of its great importance in the history tocene, when the Laurentian uplands became the centres of the continent, and because its history has so generally from which the ice sheets of the Glacial period spread out been misunderstood. To these reasons may be added a on all sides. As a result of this late chapter in the history third : through Palaeozoic and Mesozoic time the history of the region, the weathered soils of earlier periods were of the Laurentian region is for the most part a blank. swept away along with an unknown amount of firm rock, Records are wanting from the early Palaeozoic to the Pleis- leaving bare ledges, scattered boulders, and gravelly drift

to day upon a rugged upland without mountains (except in north-east Labrador), but diversified by innumerable knobs and hollows. The drainage of the region has thus been thrown into disorder; large and small lakes and marshy hollows abound; the streams are repeatedly interrupted by rapids, and frequently split into two or more channels, enclosing islands many miles in length. They are the only highways of this thinly inhabited region.

The Appalachian province is a generally hilly and mountainous belt, stretching from Newfoundland to Alabama. It seems for the most part to have belonged in the earliest times to the great pre-Cambrian app3’ land area, of which the Laurentian highland !f.cbJfn ^ 0 • p , • « nighlatias. is the more manifest representative ; for whereever the basal members of the Palaeozoic sedimentary series are found in the Appalachians, they rest upon a floor of
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