Box 15, Folder 4: Geology of Wisconsin [Wellings Atlas] 1874

Wallings Atlas of Wis

GEOLOGY

BY I. A. LAPHAM, LL.D., STATE GEOLOGIST.

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The first considerable effort to develope the geological features of the territory now constituting the State of Wisconsin, was made in 1839, by Dr. D. D. Owen, Dr. John Locke, and others, in what is known as the lead region, chiefly in the counties of Grant, Iowa, and La Fayette, in the south-western part of of the State.

This work was done in pursuance of a resolution of Congress, calling for information relative to the mineral lands of the United States, and the results were reported in an Executive document ^1 with maps, sections and drawings of fossils. The next was also made by Dr. Owen, or under his direction, on behalf of the general government, being a Reconnoissance of the Chippewa Land District which then included a large portion of the State. The results were reported in 1848 ^2 with a large map; and again more fully in 1852 in a large volume on the Geology of Wisconsin, Iowa and Minnesota.

In Foster and Whitney's Reports upon the Copper and Iron Regions of Lake Superior, (1850 & 1851) are some chapters relating to eastern and north-eastern Wisconsin.

The State has made several efforts towards a geological survey of its territory, and a number of "Annual reports" in pamphlet form have been published. The report of Hall and Whitney (1862) forms a volume of 455 pages, with maps, sections, and wood cuts of the characteristic fossils, and is the only considerable publication heretofore made by the State. Professors Edward Daniels, Ezra S. Carr, James Hall, J. D. Whitney, James G. Percival and John Murrish, have been employed in this work at various times.

A more complete geological survey of the State is now in progress, under the authority of a law approved in March, 1873; but no report of the results has yet been published.

It is proposed to give, briefly, a general idea of the principal facts already known by describing each rock-formation, in accordance with its relative age, beginning with

I. THE LAURENTIAN.

The oldest and lowest of these formations found in Wisconsin are granytic rocks,* which may be regarded as the foundation, or floor, upon which all the others have been laid.

There can be no doubt of the great age of

^1 House Ex. Doc. No. 339, 26th Cong., 1st Session 1840. ^2 Senate Ex. Doc., No. 57, 30th Cong., 1st Session 1848. * This orthography is adopted by Prof. J. D. Dana to distinguish between rocks and minerals.

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this granytic series of rocks, as was first indicated by Foster and Whitney, being so far as was known, older than any organic life and hence called Azoic: but as they are supposed to contains traces of organic remains elsewhere the name Archaean has been adopted by recent writers. They usually exist in the form of rounded or dome-shaped knolls of considerable extent and of but little elevation. Essentially, granyte consists of an aggregation of crystalline grains of quartz, feldspar, and mica; but the name is usually applied to rocks in which hornblende takes the place of mica (syenyte), and to other crystalline aggregations. When slaty in sturcture it is Gneiss, or Mica-Slate. All these forms occur in Wisconsin. Some varieties especially from the Oconto and Wolf rivers, have a great resemblance to the Scotch Granyte of which so much is now imported for ornamental purposes; but no attempt has yet been made to quarry any of our granytes, owing to their remoteness from the means of transportation, being mostly in parts of the State but little settled and improved.

Other varieties, caused by the varying constituent minerals, and their relative proportions, are found, and might be rendered useful in masonry; including fine grained and coarse, red, white, gray, mottled, light-colored, porphyritic, graphic, &c.

Granyte and Granytic rocks are found at Black River Falls, on the Wisconsin and Chippewa rivers, and at numerous other localities within the district represented on the accompanying map as "Granytic and Huronian."

It will be seen that they underlie portions of the counties of Burnett, Polk, Barron, Ashland, Chippewa, Clark, Wood, Marathon, Lincoln, Portage, Waupacca, Shawano, and Oconto. They are so uniformly covered with "drift" that it is difficult to ascertain their presence or to trace their boundaries.

II. HURONIAN ROCKS.

Resting upon these granytic prominences, and sloping away from their sides in all directions, are often found strata of chloritic, talcose, or argillaceous slates and quartzytes, supposed to have the same age as the rocks which in Canada are called Huronian. These rocks are of great practical interest on account of the masses of iron ore associated with them; most abundantly at the Penokie Iron Range, in Ashland County, and at Black River Falls, (Jackson County.) The famous iron deposits of the Marquette and Menomonee regions in Michigan are in the

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same series of rock. It is supposed that the iron range near the Menomonee extends across that river into Wisconsin and measures are in progress for ascertaining the truth of this supposition.

The Penokie iron-bearing rocks have been traced for a distance of sixty miles; always accompanied by magnetic and specular iron ores varying from a few feet to one hundred in thickness. The ore is mixed with the rock in proportions varying from one or two to eighty per cent. They have been carefully "sampled" and analyzed, so as to show their practical value; and it is believed that as the country becomes better known, richer and more easily worked deposits may be found. The completion of the Wisconsin Central rail-road will bring this now almost inaccessible region into notice.

Roofing slates are quarried in these rocks in Michigan and suitable localities may be found in Wisconsin.

Huronian rocks are found in Ashland, Bayfield, Oconto and Jackson Counties; also, in the form of quartzytes, in Sauk, Columbia and Marquette. No doubt older localities will be found when these other rocks have been more thoroughly studied. It is believed that they rest non-conformably upon the granytic rocks, as represented on the accompanying section; but this fact has not yet been confirmed by observation within this state.

The quartzytes in Sauk County show ripple marks upon surfaces now standing almost vertically; thus showing that they were once horizontal sand-beaches, that have been hardened and tilted up to their present position. They were also at a very early period broken up into boulders and pebbles that were again cemented into layers of breccia and conglomerate. Thus boulders were formed long before the glacial or ice-period. By the disintegration of these conglomerates, boulders are reproduced that originated in Archaean times.

Kaolin or Porcelain clay is found in several localities, resulting from the disintegration of the granyte and the decomposition of feldspar. Some efforts have been made to use this clay in making fire brick for lining furnaces which seem to have been successful.

Pipe clay, similar to that so celebrated among the red men, from the Coteau de Prairie, Minnesota, has been found in Barron County upon lands belonging to the Cornell University of New York. It was first discovered and described by Mr. A. Randall in

[continuation of article by I. A. Lapham, LL.D., State Geologist.]

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Owen's Report; and may hereafter be applied to purposes of ornament and use.

No limestone has yet been found associated with the Archaean Rocks in Wisconsin.

Artesian wells have shown that these ancient rocks probably underlie the whole state; they slope very gradually towards the south and west; and abruptly towards the north and east.

III. Copper-bearing Rocks.

These rocks, consisting of "trap," conglomerate and sandstone, extend from the copper mining district in Michigan into Ashland, Bayfield and Douglass counties in Wisconsin, where numerous small veins of copper have been found. Their position is intermediate between the Huronian and the sandstone of the Potsdam period; hence not only the granytic and the iron-bearing rocks but also these copper-bearing rocks are to be assigned to a pre-Silurian age; all having been deposited, metamorphosed, and tilted into their present, often highly inclined position, before the deposition of the older Silurian rocks.

As one of the results of the state survey now in progress we have the important fact that the synclinal valley or trough between Keweenaw Point and Isle Royale, occupied by the waters of Lake Superior, is continued inland in Wisconsin, both the north and the south-dipping strata being there found. This portion of the trough is filled, not with the water of the lake, but with Potsdam Sandstone in horizontal layers, covered with red, marly drift. White river and the upper waters of the St. Croix occupy this synclinal valley; the first running eastward to Lake Superior the other westward and into the Mississippi.

On the accompanying section an attempt is made to represent the relative ages and geological position of these formations and also the synclinal here spoken of. This section is partly ideal, and is intended to represent the general facts, rather than the local details which would be out of place here.

[black and white illustration] L. Superior Penokie Iron Ridge

Section Across the State. [pencil note] Complete this title

It is quite apparent [apparent] that a very long time must have elapsed, between the formation of these Archaean rocks (including under that name the copper-bearing as well as the iron-bearing series,) and that of the Potsdam sandstone resting upon them. During this time deposits of great thickness may have been accumulating in other parts of the ancient world, but none here. Dry land only existed, and the denuding agencies, then doubtless more active than now, were already at work preparing the surface for the reception of the Potsdam sandstone, when the

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proper time for its deposition should arrive.

IV. Potsdam Sandstone.

Though this rock is called a sandstone it includes layers of shale and of shaly limestone. We find here the first certain traces of animal and vegetable life known in Wisconsin. Among the fossils, found chiefly in the calcareous layers is a large Trilobite, an animale of the same class as the lobster, and a Lingula, very much like those living in our own times.

Wave-marks upon the sandstone show that the winds and the waves were then at their work of wearing down and rebuilding continents. The sandstone everywhere rests upon the upturned edges of the Archaean rocks or is abutted against their sloping sides. At the junction of this sandstone with the trap rocks of the copper-bearing series it is often disturbed and broken into irregular fragments; but these cases admit of explanation not inconsistent with the supposition of the older date of the trap. Perhaps they may be due to the expansion caused by changes of temperature, as is often seen in ice on the smaller lakes.

It will be seen by reference to the map that the sandstone occupies a very considerable district in the central parts of the state with branches extending eastward to the Menomonee river (of Green Bay) and westward to the St. Croix, having a V shape, the arms embracing the Archaean rocks. Following up the course of the St. Croix the sandstone curves around the elder rocks and reappears on the south shore of Lake Superior. It has a thickness of about five hundred feet where fully developed. Further explorations will, doubtless, show that it exists in outliers within the district now represented as Archaean; and artesian wells have shown its presence beneath the newer rocks in various places.

Potsdam sandstone is not often sufficiently indurated to constitute good building stone. It is easily crumbled by frost and rain; and swallows have no difficulty in making their nests in it, in many places. The brown

[black and white illustration] Level of the Sea

sandstone from Lake Superior is the most notable exception to this statement. The disintegrating and wearing agencies have cut channels of great width and depth through this rock, along the course of the larger rivers, reaching in many cases down to the crystalline rocks. By the unequal effects of these agencies the rock is often left in sharp, bold cliffs and isolated standing rocks, presenting many strange forms, much to the delight of the photographers. One of these in Sauk County is called "The nigger-head" on account of its resemblance to the head of a

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negro. Its porous nature renders it peculiarly a water-bearing rock, and there are, doubtless, many places where the water could be brought to the surface, as at Sparta, by artesian wells.

V. Lower Magnesian Limestone.

This rock which is the equivalent of the Calciferous sandstone of New York, occurs in large isolated patches resting immediately upon the Potsdam sandstone, often capping the tops of hills whose sides are made up of sandstone. If we follow the southern boundary of the Potsdam sandstone as shown upon the map, all the way from the Menomonee (of Green Bay) to the St. Croix, we shall have the position of the lower Magnesian Limestone.

To the south and east it passes under the next rock. It is highly siliceous, containing much sand, chert, drusy quartz, and even layers of sandstone. It is often difficult to trace the exact boundary between this rock and the Potsdam sandstone below.

It has a thickness of about two hundred feet. Some ores of lead and copper have been found in it, giving rise to hopes of finding valuable mines; hopes which have not been realized. In many places it affords a valuable and beautiful building stone; and it has been extensively quarried for that purpose in some favorable localities, especially near Prairie du Chien. The sandy soils of the state are largely made up of particles of this and other limestones, thus yielding a soil of great fertility and easily worked.

VI. St. Peter's Sandstone.

Above the last named rock is another sandstone about one hundred feet in thickness, very uniform in texture, of various colors, white, grey, yellow, brown and red; often forming prominent cliffs which are gradually crumbling into sand. It is the same that has been called the upper Sandstone to distinguish it from the Potsdam which was called the lower Sandstone. It underlies the lead-bearing rocks in the south-west part of the state, and its determination therefore becomes

[black and white illustration] Iron Ridge Potash Kettles L. Mich

a matter [matter] of much practical importance. being the bed-rock in and below which no workable veins of lead or zinc ores have been found. Many river valleys have been cut down through the superincumbent limestones into this soft stratum of sandstone. It is traced from near Beloit northward through the counties of Rock, Jefferson [Jefferson], Dodge, Fond du Lac, Winnebago, Outagamie and Shawano; Eastward of this line it is concealed by overlying rocks.

In some localities it affords [affords] a pure white sand suitable for the manufacture of glass, and for

[continuation of article by I. A. Lapham, LL.D., State Geologist.]

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other purposes where a pure silex, is needed. 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 spots 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.

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 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 Eastern-most limit 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 bituminous, shaly limestone, often so well saturated with bitumen as to burn with a blaze.

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 names 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. Peters' sandstone. These mines are extensively worked for lead and zinc.

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 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

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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 lead veins have yet been found.

IX. Cincinnati Group.

Resting immediately upon the Galena Limestone is found a series of highly fossiliferous shales with intercolations 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.

X. Clinton Group.

The limestones and shales belonging to this group form a prominent escarpment in Dodge, Fond du Lac, Calumet and Brown counties. They are scarcely to be distinguished from the Niagara Group above. The great deposit of oolitic iron ore at Iron Ridge in the first named county, belongs to this group, and makes its study one of great practical importance. Ore of the same character has been found in the same connection eastward to New York and southward to Tennessee. Trace of it are found at various other places in this state but not yet in such quantity as to justify the investment of capital for its extraction.

A large amount of the Iron Ridge ore is brought to Milwaukee to be mixed with ores from Lake Superior, by which means iron of special qualities may be produced.

It is also smelted at the mine and at Mayville, near by. In quantity it is here, practically, inexhaustible.

XI. Niagara Limestone.

The rock over which the waters are precipitated at Niagara in New York, has been traced through Canada and Upper Michigan to the islands obstructing [obstructing] the channel between Lake Michigan and Green Bay; and thence along the west shore of that lake into Illinois. It is known throughout this great extent by lithological characters and by the occurrence of certain fossils. It is quarried for building purposes at many places.

Like all the other limestones of Wisconsin this contains a large percentage of carbonate of magnesia, being therefore a Dolomite

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rather than a limestone. Some small streams, falling over these rocks, have worn out channels, forming miniature representations of the great falls at Niagara.

XII. Racine Limestone.

The rock found, and quite extensively quarried near Racine in this state has been named the Racine Limestone, though perhaps it should be regarded as the upper part of the Niagara Group.

It makes quicklime of an excellent quality. When much exposed to the weather it becomes yellow and soft. It is characterized by some peculiar fossils called crinoids, not found in the layers below.

XIII. Salina Group.

At a single locality on Mud Creek near Milwaukee is found a very thin-bedded limestone which has been referred to this Group. It contains no fossils. Fragments found in the drift indicate a much greater extent of this rock than can be ascertained in any other way. Its stratigraphical relations, though obscured by drift, are with the Racine limestone below, and the Devonian limestone of the Milwaukee river above. Its association, in other states, with salt and gypsum makes the study of this formation one of considerable importance. Only small fragments of gypsum, have been found; and salt is an ingredient in most of the waters that have been analyzed.

XIV. Devonian Limestone.

The newest of the rock-formations proper, found in Wisconsin, are certain limestones along the lake shore north of Milwaukee and in the bed of the river above Humboldt, which contain traces of fish remains and certain other fossils showing that they belong to the Devonian age -- the age of fishes. The investigations of the state survey, now in progress will, doubtless, throw some light upon the character and extent of this group of rocks. Some of the layers appear to be of the same age as the water-limestones of Louisville [Louisville?] Ky., and may have the same useful quality.

The existence of the Black Shale in the Drift at Milwaukee shows that we have ascended almost to the horizon of that highly bituminous rock.

XV. Drift.

Under this head we may include all those deposits of clay, sand, gravel and boulders that are spread out uncomfortably upon all the before mentioned rocks. They cover equally the newest and the oldest of the series and are therefore the last results of that long contained succession of event that were instrumental in producing that part of our great continent included in Wisconsin.

Evidence derived from the existence, in other countries, of extended series of rocks between the Devonian and the Drift, shows that an immense interval of time was interposed, during all which Wisconsin was dry land -- subject to the abrading influences of rains and frosts.

Drift shows itself in three distinct forms;

[continuation of article by I. A. Lapham, LL.D., State Geologist.]

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1st, A hardpan or unstratified boulder clay, resting directly upon the smoothed and striated rock-surface, very hard and tough, and destitute of fossils. This is the original deposit under the great glacier, a thousand feet or more in depth, which once crept slowly but surely over the surface; -- 2d, Beds of sand and gravel separated from the hardpan by the action of running water after the glaciers began to melt away; and, 3d, Beds of fine clay also separated from the hardpan at the same time, but deposited in the comparatively still water of the numerous great lakes that then existed. This action of rivers and lakes in assorting the materials of the Drift is continued, though upon a much smaller scale, to the present day.

The hardpan affords firm banks for our lakes, and is the dread of well-diggers: the gravel and sand are useful in road-making and for mortar; and the clay-beds afford the material for our white or cream colored brick.

After this glacial period, when the ice had retired, vegetation was spread over the land, and animals of various kinds began to appear. Among these were some now entirely extinct, including the fossil elephant (mammoth) and the mastodon. During this time trunks of trees became buried in the new deposits now often dug up from wells &c. The great amount of rain-fall filled the valleys with large rivers carrying away the looser materials on the surface but leaving the heavier boulders perched upon the surface, as if they had been dropped from an iceberg.

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These strong currents probably were the means of forming many of the ridges and hillocks that now diversify the surface of the ground.

It is now impossible to know what was the condition of the surface of the state and what were the plants and animals, just previous to this glacial epoch, for all traces of them were effaced by the rasping and grinding effects of the moving ice.

Valleys were filled up and hills cut down; great basins were scooped out to form the beds of the future lakes.

When the ice was withdrawn the whole surface was covered with drift.

It still remains to be accounted for that in the lead-region in this state there is almost a total absence of the Drift phenomena.

Pre-historic Man in Wisconsin.

A race of people once occupied our soil of whom very little is known except what can be gathered from their works and a few fragments of their skeletons. With his introduction geological history properly ends; and it becomes important to know whether he was, or not, cotemporary with the mammoth and mastodon.

The indications now are that they were quite different in many respects from the modern Indians, though these may be their descendants. In habits they were similar [similar] to other savage peoples -- using the bow, and an arrow tipped with flint, to secure their game or punish their enemies.

He made use of native copper (which he brought from Lake Superior, or found in the

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glacial drift) in making his arrow heads, knives, chisels, axes &c., though it is doubtful whether he had the skill to mould this metal into form. His implements of unpolished stone and of hammered copper, are now found buried many feet in the earth; thus indicating the lapse of many ages since his time.

But perhaps the most striking peculiarity of the Pre-history man of Wisconsin, was his

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habit of throwing up mounds of earth in the form of animals and of man. For what purpose these were erected can now, of course, be only an object of conjecture. That they had some significance seems quite evident.

We here give a carefully prepared figure of this pre-historic man and one of the animals as represented in the mounds. They each have a total length of one hundred and twenty-five feet; the former in Sauk County, was surveyed by Mr. Wm. H. Canfield; the latter

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near Cassville, Grant County, surveyed by Mr. Moses Strong.

Milwaukee, July, 1874