ENPages
p.16
16
Though usually too soft to be used as a building stone, it is occasionally quarried for that purpose. One quarry near Darlington in La. Fayette county affords a beautiful brown stone like that from Lake Superior. The colors are often very bright and arranged in sports and stripes in a picturesque manner.
Like some other rocks it often assumes strange forms in consequence of unequal weathering, affording "Wonder= rocks" for the admirers of wild rocky scenery.
16
p.17
17
VII Buff and Blue Limestones.
These with the next (Galena Limestone) belong to the Lower Silurian age, and to the Trenton period. They rest directly upon the St. Peter's Sandstone and are conformable to it, thus showing apparently a continuous formation; there being little or no Evidence of any interval of time between the two. They are found along the hillsides in the lead=region but Exist in greatest force in Rock County, and thence northward through Jefferson Dodge Fond du Lac, Winnebago, Outagamie, Brown and Oconto; this being their Easternmost limits in Wisconsin, They have together a thickness of about one hundred and twenty feet; and are the first to show an abundant display of animal life. These remains are all of marine origin showing a deposition upon the bottom of an ancient Sea. The Existence of plant=life in its lowest forms is shown, not only by the remains of Fucoidal stems, but by a layer of highly bitumenous shaly limestone; often so well saturated with bitumen as to burn with a blaze.
17
p.18
18
VIII Galena Limestone.
This rock, belonging to the Trenton period, is found chiefly in the lead= region in this and the adjoining states of Iowa and Illinois. It has not been recognized among the rocks at the East or at the west of us. It is so named because it is well developed at Galena in Illinois, and because it is the rock that chiefly bears the lead ore (galenite) found in that district. It has a thickness of about two hundred and fifty feet. Like all other limestones heretofore found in this state it is highly Magnesian (dolomite) and was at first named the Upper Magnesian Limestone,
Veins of lead, Zinc, and copper occur in great numbers, Extending downwards often into the limestones below but never into the St. Peter's sandstone. These mines are Extensively worked for lead and Zinc.
18
p.19
19 At the surface, the Galena Limestone becomes softened, and colored yellow by Exposure to the weather and by the percolation of water. The yellow particles are washed by rains into the lower grounds where they constitute the surface soil from which abundant crops are raised; thus uniting a mining and an agricultural interest in this rock. The Galena Limestone is distinguished by the occurrence of a peculiar fossil of an obscure nature having Eccentric rows of cells, arranged much like the ornamental [ornamental] work put upon the back of a watch. These are aggregated into a broad disc having the general appearance of the receptacle of the sun flower. From this circumstance it is called Receptaculites.
The rock Extends into the Eastern part of Rock County, and the central and northern portions of Jefferson; but here no dead veins have yet been found.
19.
19 19
p.20
20 IX Cincinnati Group.
Resting immediately upon the Galena Limestone is found a series of highly fossiliferous shales with intercalations of limestone, heretofore called the Hudson River Group but now generally known under the name adopted above; the same rocks with the same fossils being found at Cincinnati, Ohio, where they are well developed, and where they have been thoroughly studied. They have a thickness, in Wisconsin, of about one hundred feet. They occur on the slopes of the several mounds in the lead-region, and at various other places. It is only where these soft shales have been protected from denudation, by the limestone above, that they have been preserved for our present inspection; when removed, by natural causes the unsupported limestone falls often in large masses.
These shales in some localities have an External resemblance to the shales of the Coal - bearing rocks, and they have been Explored in the Expectation of finding coal.
The slightest knowledge of Paleontology shows that they were laid down at a period long before the Existence of those peculiar Conditions which gave origin to coal.
20
