Lake Superior is called by the Chippewas a sea.
The superficial area of the lake has been computed by Mr. Darby at a little under nine hundred billions of feet, and its depth at nine hundred feet. By the latest surveys and estimate, the altitude of Lake Superior above tide water, is about six hundred and forty feet.[ [62] Allowing Mr. Darby's computation to be correct, this would sink its bed far below the surface of the Atlantic.
This lake has been the theatre of very extensive volcanic action. Vast dykes of trap traverse its northern shores. One of the principal of these has apparently extended across its bed, from northeast to southwest, to the long peninsula of Keweena, producing at the same time, the elevated range of the Okaug Mountains. One of the most remarkable features of these dykes is the numerous and extensive veins of native copper which characterize them. Subsequent convulsions, and the demolition of these ancient dykes, by storms and tempests, have scattered along its shores abundant evidence of the metal and its ores and veinstones, which have attracted notice from the earliest time. The geology of its southern coasts may be glanced at, and inferred, from the subjoined outlines.
Geological outline of Lake Superior.
The teachings of topography, applied to commerce, are wonderful. A longitudinal line, dropped south, from this point, would cross the Mississippi at the foot of Lake Pepin, and pass through Jefferson city on the Missouri. When, therefore, a ship canal shall be made at St. Mary's Falls, vessels of large tonnage may sail from Oswego (by the Welland canal) and Buffalo, through a line of inter-oceanic seas, nearer to the foot of the Rocky Mountains, by several hundred miles, than by any other possible route. A railroad line from Fond du Lac west to the Columbia valley, would also form the shortest and most direct transit route from the Pacific to New York. Such a road would have the advantage of passing through a region favorable to agriculture, which cannot but develop abundant resources.
CHAPTER VIII.
Proceed up the St. Louis River, and around its falls and rapids to Sandy Lake in the valley of the Upper Mississippi—Grand Portage—Portage aux Coteaux—A sub-exploring party—Cross the great morass of Akeek Scepi to Sandy Lake—Indian mode of pictographic writing—Site of an Indian jonglery—Post of Sandy Lake.