its vertical layers occasion much inconvenience in passing the portage. SERPENTINE is found in small masses on Lake Superior, containing grains of native copper. It is also said to be found in connection with the celebrated copper rock from the Ontonagon river, now in the cabinet of the National Institute at Washington. To discover the locality of this rock in its native beds, then, becomes an important desideratum. According to Cleveland, Serpentine is associated with primitive and transition rocks, and exists in beds in gneiss, mica-slate, and argillite; so that in any part of the primitive district of our Territory we may expect to find it. GRANULAR QUARTZ constitutes the Falls of Pickagama, on the Mississippi; and GREENSTONE, having sometimes a columnar structure, is found on the St. Croix river, commencing twenty-four miles above the lake, and constituting the rocky glen at the Falls.

The mineral district of Lake Superior, which is now beginning to attract so much attention, lies mostly in Michigan, between the Montreal river and Kewena Point; and, therefore, does not properly require a description here. Its geological character is entirely different from the Wisconsin lead and copper district. But the trap dykes with which the veins of copper ore are more or less associated, are known to extend northward to the Menomonee and Wisconsin rivers; and hence it is supposed that copper may hereafter be discovered in all the intermediate country from Lake Superior to the region of lead and copper mines south of the Wisconsin river. Some recent discoveries of copper on the Menomonee, the Baraboo, and Kickapoo rivers seem to favor this supposition. At La Pointe, also, the same formations exist; and future explorations may develope valuable mines in that vicinity.

II. The country next to the Primitive district, extending along the Mississippi from the Falls of St. Anthony to the borders of the Mineral district, a short distance south of the Wisconsin river, and extending up the branches of

the Mississippi to their respective falls, is composed of SANDSTONE, resting upon, and surmounted by limestone. In many places only one of these rocks exists, the others being below the deepest valleys, or have been carried away or destroyed by some unknown cause. The sandstone is mostly pure, and "white as the driven snow"-resembling white sugar in appearance, but is occasionally colored by iron rust with red, orange, or dark tints: at other times it is yellowish, and has been compared to the finer varieties of Muscovado sugar. These colors are frequently arranged in stripes or bands. It is soft and easily crumbles-so soft, says Featherstonhaugh, that the swallows, in great numbers, have been able to pick holes in it, on the Wisconsin river, to build their nests. The grains appear to be perfect quartz crystals, and not beach sand smoothed and ground by the action of water and then hardened into rock. This pure sand must ere long become the material for the manufacture of glass. The sandstone is sixty feet in thickness at the Falls of St. Anthony, and about the same at Prairie du Chien; but along the Wisconsin Hills it attains a thickness of over two hundred feet. The cliffs along the Mississippi, for a distance of thirty-five miles below the Falls of St. Anthony, appear to be composed chiefly of this crumbling sandstone. Large blocks are occasionally undermined and fall down, lying in confused heaps at the base of the bluffs. The rivers running through the district where this sandstone prevails, are characterized by shallow water, filled with moving sand, forming bars, that are constantly carried away from some points, and accumulated at others, rendering the navigation difficult. By far the larger proportion of the river bluffs along the Mississippi are calcareous, and present high perpendicular rocky fronts towards the river, supported by immense quantities of broken fragments at the base, extending usually half way to the summit. They are said to attain their greatest elevation in the vicinity of Lake Pepin. The limestone which lies above

the sandstone in Wisconsin, was found by Dr. Locke to be the same that he had described in Ohio as the "blue limestone," and which constitutes the hills surrounding the city of Cincinnati. It is considered by most geologists as the equivalent of the "Trenton limestone" of the New York geologists; but Mr. Hall thinks it belongs to a more recent period. All the rocks of this district are referable to the Champlain division," which is the first or oldest of the transition rocks in the United States.

III. The third Geological district is that known (and very properly) as the "MINERAL COUNTRY," the word mineral being used here to denote an ore of some useful metal. The lead-bearing rock is a loose, porous, yellowish limestone, resting upon the "blue limestone," and is deemed equivalent to the "cliff limestone" of Dr. Locke of Ohio, and the "Niagara limestone" of the New York geologists. It is therefore the GEODIFEROUS LIMESTONE of the late Prof. Eaton, a name which ought to be restored, as having been first applied to this rock, and being at least as free from objections as either of the others. Above the geodiferous or lead-bearing rock, we find in this district the cornitiferous rock of Eaton, constituting the "mounds," throughout the mineral district, and known by the quantities of chert or flint, or "quartz formation," which it contains. The boundaries of this district, according to Dr. Owen, run nearly parallel with, and a few miles south of Wisconsin, from the Mississippi to the Blue Mounds, and thence down the Sugar river nearly to the south line of the Territory, where it diverges suddenly to the west and crosses that line near the Peckatonica. It embraces about sixty-two townships, constituting by far the larger proportion of the lead district of the Upper Mississippi; as the extent of country from which this mineral is obtained in Illinois is only ten townships, and in Iowa Territory only eight. The surface rock in this district being limestone, and the face of the country not being mountainous, as is usually the case in mining

countries, we find that the lands about our lead mines are as valuable for agricultural purposes as almost any other in the west, thus affording this district advantages not to be found in combination elsewhere; for, except in this case, the country which is valuable for its mines, is good for nothing in the eyes of an agriculturist. The theoretical geologist will find a hard problem to solve in his endeavor to account for the almost total absence of those boulders of primitive rock in the mineral district, which are so abundant elsewhere in the Territory.

In Silliman's Journal of Science and Arts for July, 1842, is an article by James P. Hodge, "on the Wisconsin and Missouri Lead Region," which contains the most correct account that has recently been published of the manner in which the lead is found in the rock; the general character of the mineral country, &c.; it is therefore hoped that no apology is necessary for introducing here the following ex

tract:

"Though the cliff' (Geodiferous) limestone, the formation that contains the lead ore, occupies a greater extent of country, it is in this portion only that circumstances seem to have been favorable for the production of fissures containing the ore. Its strata appear uniformly horizontal, until, by tracing them some miles, a prevailing dip to the south is discovered. The lead region is a rolling, hilly country, the hills sometimes covered with an open growth of oak, but as often entirely free from timber, and clothed with the tall prairie grass only. The summits maintain a general level, except where it is broken by the natural mounds' (the two Blue Mounds, the Platte Mounds, Sinsinawa Mounds, &c.), which rise several hundred feet above it. In these the limestone appears more siliceous than is noticed elsewhere, and its superior hardness may in part have been the cause of these mounds remaining like monuments of the devastating currents that must have given the surface around its present form; while the huge

blocks, tipped out of their horizontal position, lie on the steep sides, as additional evidence of the wasting waters.

"Throughout the extensive tract defined as the lead region, lead ore may be sought for with prospect of success, on every township, and on almost every square mile. And, fortunately, it is so well watered, and the little streams. have so rapid a fall, that power for furnaces may almost always be obtained near the mines. New discoveries are continually made, and with every one, further light is thrown upon the true character of the ranges of fissures containing the lead and copper ores, by which results they can be traced with greater certainty from one tract to another, without depending entirely on the present imperfect mode of prospecting.'

"Beneath the cliff limestone is a thin stratum of blue limestone, and this rests on a body of brown sandstone. As one goes from the southern townships of Wisconsin towards the north, this blue limestone is observed to become higher and higher in the hills, and the lead diggings to be everywhere above it. Though the sandstone rocks come out in bold bluffs on the sides of the hills, no veins of ore are ever found in them; but in the cliff limestone above they are found, though the rock and its fissures lie hid under a great depth of soil.

"These fissures are of every degree of width, from fifty feet down to thin cracks; all of them do not contain ore; the large chambers, when they have any mineral in them, are lined on the walls with a coating of lead ore, seldom over a foot thick, while the interior is filled with clay. Sometimes across the crevices run horizontal layers of galena; and again it occurs in loose 'chunks' in the clay of the fissures, or of the soil above, and again it runs in a vertical sheet down, or still again filling narrow fissures in the appearance of a vein and of a bed in the solid rock. But lead is not the only ore these fissures contain. Mixed with it in every proportion, and even sometimes getting the bet