In the neighborhood of Quebec, a dark clay slate generally appears, and forms the bed of the St. Lawrence as far as Lake Ontario, and even at Niagara; bowlders and other large masses of rock, however, of various kinds, occur in detached portions at many different places. The great elevated ridge of broken country running toward the Ottawa River, at the distance of from fifty to one hundred miles from the north shore of Lake Ontario, and the course of the St. Lawrence, is rich in silver, lead, copper, and iron. On the north shore of the Saguenay, the rugged mountains abound in iron to such an extent as to influence the mariner's compass. The iron mines of St. Maurice[154] have been long known, and found abundantly productive of an admirable metal, inferior to none in the world; it is remarkably pliant and malleable, and little subject to oxydation. In 1667, Colbert sent M. de la Potardiere, an experienced mineralogist, to examine these mines; he reported the iron very abundant, and of excellent quality, but it was not till 1737 that the forges were established by the French: they failed to pay the expenses of the speculation; the superintendent and fourteen clerks, however, gained fortunes by the losses of their employers. There is no doubt that immense mineral resources remain undiscovered among the rocky solitudes of Lower Canada. Marble of excellent quality, and endless variety of color, is found in different parts of the country, and limestone is almost universal. Labrador produces a beautiful and well-known spar of rich and brilliant tints, ultra-marine, greenish yellow, red, and some of a fine pearly gray. In Upper Canada, the country north of Lake Ontario is generally characterized by a limestone subsoil resting on granite. The rocks about Kingston are usually a very compact limestone, of a bluish-gray color, having a slight silicious admixture, increasing as the depth increases, with occasional intrusions of quartz or hornstone. The limestone strata are horizontal, with the greatest dip when nearest to the elder rock on which it rests; their thickness, like the depths of the soil, varies from a few feet to a few inches: in these formations many minerals are observed; genuine granite is seldom or never found.