Page:Popular Science Monthly Volume 19.djvu/245

Rh Connecticut, almost all of Rhode Island, and eastern Massachusetts, with some slight exceptions, where islands of later rock occur, as southwest from Boston and about Lowell. Nearly all New Hampshire is covered by it, and in Canada it forms another strip parallel to the first, while eastward it constitutes the surface rock of much of Maine, wherein, at last, it breaks up into scattered patches, lying like Titanic stepping-stones, from Augusta northward to the desolate horn of Newfoundland. One of these districts surrounds Mount Katahdin; another, in a long, easterly-deflected strip of land, runs from Mount Desert northward to Chaleur Bay, New Brunswick; while from Machias Bay a third streams northward in a narrow ribbon.

Separated areas are found along the southern shore of Newfoundland and upon Cape Breton Island.

In the United States four other extensive archæan territories exist east of 95° west longitude; one in the Adirondack region, embracing the immense northern park of New York as far north as Malone, and stretching southward almost to Saratoga Springs, bordered by the State line, and, linking, through a narrow aperture between surfaces of subsequent strata, with the enormous reaches of azoic land which form Quebec and Ontario Provinces, it merges into two lateral expansions, on one side into the limitless highlands of Labrador, on the other into the ridges, valleys, and plateaus of the lake country northward to the Arctic Circle.

The second area is in northern Wisconsin and Michigan, embracing the Marquette region, famous for its ores. The third is a neighboring and related province in eastern Minnesota, from the South Bend on the Minnesota River, widening northward and uniting with the Canadian area about the Rainy Lake region. The fourth, a diminutive outlier, comprises the Iron Mountain and Pilot Knob country in southeast Missouri.

These large spaces of archæan rock represent the floor-layers, as now exposed in the eastern United States, of the continent's superstructure. In these parts of our country they form the surface-rock, and whether they have been always raised beyond the reach of sedimentary deposit or have been scoured and relieved by frost and flood of superincumbent strata, whether their present extent is conterminous with their limits, as once revealed above the level of primeval seas, or whether shrunken by subsidence and partially obliterated by later formations, they are at any rate outcrops of the vast bedding on which ocean and continent alike repose. But when we examine these aged stones we find that they themselves appear as the cemented residues and stratified deposits formed from some yet preëxistent firmament of land. In serial bands, conforming to each other, as book lies against book, we find limestone, slates, sandstones, quartzites, schists, and gneiss, and we know now that these regular layers, hard, distinct, and characterized by color, constituents, and adventitious minerals, were