The history of Columbia County, Wisconsin, containing an account of its settlement, growth, development and resources; an extensive and minute sketch of its cities, towns and villages--their improvements, industries, manufactories, churches, schools and societies; its war record, biographical sketches, portraits of prominent men and early settlers; the whole preceded by a history of Wisconsin, statistics of the state, and an abstract of its laws and constitution and of the constitution of the United States
Chamberlin, T. C.
Topography and geology, pp. -120 PDF (5.3 MB)
HISTORY OF WISCONSIN. CINCINNATI SHALES. A change ensued upon the formation of the Galena limestone, by virtue of which there fol- lowed the deposition of large quantities of clay, accompanied by some calcareous material, the whole reaching at some-points a thickness of more than 200 feet. The sediment has never become more than partially indurated, and a portion of it is now only a bed of compact clay. Other portions hardened to shale or limestone according to the material. The shales are of various gray, green, blue, purple and other hues, so that where vertical cliffs are exposed, as along Green bay, a beautiful appearance is presented. As a whole, this is a very soft formation, and hence easily eroded. Owing to this fact, along the east side of the Green-bay-Rock-river val- ley, it has been extensively carried away, leaving the.hard overlying Niagara limestone projecting in the bold cliffs known as "The Ledge." The prominence of the mounds in the southwestern part of the state are due to a like cause. Certain portions of this formation abound in astonish- ing numbers of well preserved fossils, among which corals, bryozoans, and brachiopods, pre- dominate, the first named being especially abundant. A little intelligent attention to these might have saved a considerable waste of time and means in an idle search for coal, to which a slight resemblance to some of the shales of the coal measures has led. This formation underlies the mounds of the lead region, and forms a narrow belt on the eastern margin of the Green-bay-Rock- river valley. This was the closing period of the Lower Silurian Age. CLINTON IRON ORE. On the surface of the shales just described, there were accumulated, here and there, beds of pecu- liar lenticular iron ore. It is probable that it was deposited in detached basins, but the evidence of this is not conclusive. In our own state, this is chiefly known as Iron Ridge ore, from the remarkable development it attains at that point. It is made up of little concretions, which from their size and color are fancied to resemble flax seed, and hence the name " seed ore," or the roe of fish, and hence oblitic ore. "Shot ore" is also a common term. This is a soft ore occur- ring in regular horizontal beds which are quarried with more ease than ordinary limestone. This deposit attains, at Iron Ridge, the unusual thickness of twenty-five feet, and affords a readily accessible supply of ore, adequate to all demands for a long time to come. Similar, but much less extensive beds, occur at Hartford, and near Depere, besides some feeble deposits elsewhere. Large quantities of ore from Iron Ridge have been shipped to various points in this and neigh- boring States for reduction, in addition to that sme'ted in the vicinity of the mines. NIAGARA LIMESTONE. Following the period of iron deposit, there ensued the greatest limestone-forming era in the history of Wisconsin. During its progress a series of beds, summing up, at their points of great- est thickness, scarcely less th in eight hundred, feet, were laid down. The process of formation was essentially that already described, the accumulation- of the calcareous secretions of marine life. Toward the close of the period, reefs appeared, that closely resemble the coral reefs of the present seas, and doubtless have a similar history. Corals fo.m a very prominent element in the life of this period, and with them were associated great numbers of mollusks, one of which (Pentamerus oblangus)-sometimes occurs in beds not unlike certain bivalves of to-day, and may be said to have been the oyster of the Silurian seas. At certain points, those wonderful animals, the stone lilies (Crinoids), grewý in remarkable abundance,, mounted on stems like a plant, yet true animals. Those unique crustaceans, the trilobites, wereconspicuous in numbers and variety, while-the gigantic cephalopods held sway over the life of the seas. In the vicinity of th2 reefs, 118
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