Lake Superior never freezes over, but the bays are sealed up in winter, and a rim of ice extends to some distance all around the shore.
The rocks around the lake are very ancient, belonging principally to the Laurentian and Huronian systems of the Azoic series, overlaid in some places, especially on the s. side, with patches of the lower Silurian; The prevalent Laurentian rock is orthoclase gneiss. Among the Huronian rocks are greenstones, slates, conglomerates, quartzites, and limestones. The lower Silurian rocks are soft sandstones. There is everywhere much evidence of glacial action.
The Huronian rocks are well stored with useful minerals. The copper and iron mines of the s. side are celebrated for their extent and richness, and there is every reason to think that the mineral resources of the British side are equal to those of the Ameri can, although as yet comparatively undeveloped. The richest copper-mines are situated near Kee-wee-naw point. The metal occurs principally native, and sometimes in single masses of great size. One was met with in 1853, which measured about 40 ft. in length, and was calculated to weigh about 400 tons. Native silver is found associated with the native copper, and sometimes intimately mixed with it. A rich vein in an islet in Thunder bay (British side) yielded in 1870-72 silver to the value of $1,230,000. Gold has been found in small specks at Namainse on the British side. Lead ore occurs
in some places. The beds of hematite, or red iron ore, at Marquette, on the s. side, are of wonderful extent. The ore is conveyed by a railway to the harbor, thence by ves sels to, Cleveland, on lake Erie, and thence by rail to Pittsburg, where it is smelted.
The fisheries of lake Superior deserve notice, The delicious white-fish and the gray trout abound, as well as other kinds of fish. The Canadian legislature passed a law in 1865 to put a stop to the wholesale destruction of them on the spawning grounds.
The shores of lake Superior are frequented by bands of the Ojibbeway tribe of aborigines. They are of very pure blood, retain in a great measure their primitive habits, and many of them are still pagans. They seem incapable of adapting them selves to the settled life of the white man.
The white population of the British shore of lake Superior consist as yet only of the fishermen and explorers who visit the region during summer; and of miners, who extract the silver ore from veins recently discovered on Silver island, near Thunder bay. But on the American shore a number of thriving towns have sprung up. All these towns are connected with mines, little attention being yet paid to agriculture. Marquette, near the eastern end of the lake, is connected by a railway with Green bay, on lake Michigan, and thus with Milwaukee and Chicago. A telegraph line has been established.