The History of Rock County, Wisconsin: Its Early Settlement, Growth, Development, Resources, Etc., Part 18

Author: Wesern historical company, Chicago, pub
Publication date: 1879
Publisher: Chicago : Western Historical Co.
Number of Pages: 899

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THE GALENA LIMESTONE.

With scarcely a change of oceanic conditions, limestone deposit continued, so that we find reposing upon the surface of the Trenton limestone, 250 feet, or less, of a light gray or buff colored highly magnesian limestone, occurring in heavy beds, and having a sub-crystalline struc- ture. In the southern portion of the state, it contains but little shaly matter, but in the north- eastern part, it is modified by the addition of argillaceous layers and leaves, and presents a bluish or greenish-gray aspect. It receives its name from the sulphide of lead,-galena, of which it contains large quantities, in the southwestern part of the state. Zinc ore is also abundant, and these minerals give to this and the underlying formation great importance in that region. Else- where, although these ores are present in small quantities, they have not developed economic importance. This limestone, it will be observed by consulting the map, occupies a large area in the southwestern part of the state, and a broad north and south belt in east-central Wisconsin. It will be seen that our island is growing apace by concentric additions, and that, as the several formations sweep around the central nucleus of Archaan rocks, they swing off into adjoining states, whose formation was somewhat more tardv than that of Wisconsin.

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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 oolitic 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 than 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 form a very prominent element in the life of this period, and with them were associated great numbers of mollusks, one of which (Pentamerus oblongus) 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), grew in remarkable abundance, mounted on stems like a plant, yet true animals. Those unique crustaceans, the trilobites, were conspicuous in numbers and variety. while the gigantic cephalopods held sway over the life of the seas. In the vicinity of the reefs,

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TOPOGRAPHY AND GEOLOGY.

there seem to have been extensive calcareous sand flats and areas over which fine calcareous mud settled, the former resulting in a pure granular dolomite, the latter in a compact close-textured stone. The rock of the reefs is of very irregular structure. Of other portions of the formation, some are coarse heavy beds, some fine, even-bedded, close-grained layers, and some, again, irregu- lar, impure and cherty. All are highly magnesian, and some are among the purest dolomites known. The Niagara limestone occupies a broad belt lying adjacent to Lake Michigan.

LOWER HELDERBERG LIMESTONE.

On Mud creek, near Milwaukee, there is found a thin-bedded slaty limestone, that is believed to represent this period. It has neglected, however, to leave us an unequivocal record of its history, as fossils are extremely rare, and its stratigraphical relations and lithographical character are capable of more than one interpretation. Near the village of Waubeka in Ozaukee county, there is a similar formation, somewhat more fossiliferous, that seems to repre- sent the same period. The area which these occupy is very small and they play a most insignifi- cant part in the geology of the state. They close the record of the Silurian age in Wisconsin. During its progress the land had been gradually emerging from the ocean and increasing its amplitude by concentric belts of limestone, sandstone and shale. There had been no general disturbance, only those slight oscillations which changed the nature of the forming .rock and facilitated deposition. At its close the waters retired from the borders of the state, and an interval supervened, during which no additions are known to have been made to its substructure:

DEVONIAN AGE. HAMILTON CEMENT ROCK.

After a lapse of time, during which the uppermost Silurian and the lowest Devonian strata, as found elsewhere, were formed, the waters again advanced slightly upon the eastern margin of the state and deposited a magnesian limestone mingled with silicious and almuninous material, forming a combination of which a portion has recently been shown to possess hydraulic properties of a high degree of excellence. With this deposition there dawned a new era in the life-history of Wisconsin. While multitudes of protozoans, radiates, mollusks and articulates swarmed in the previous seas, no trace of a vertebrate has been found. The Hamilton period · witnessed the introduction of the highest type of the animal kingdom into the Wisconsin series. But even then only the lowest class was represented - the fishes. The lower orders of life, as before, were present, but the species were of the less ancient Devonian type. Precisely how far the deposit originally extended is not now known, as it has undoubtedly been much reduced by the eroding agencies that have acted upon it. That portion which remains, occupies a limited area on the lake shore immediately north of Milwaukee, extending inland half a dozen miles. The cement rock proper is found on the Milwaukee river just above the city. At the close of the Hamilton period the oceanic waters retired, and, if they ever subsequently encroached upon our territory, they have left us no permanent record of their intrusion.

The history of the formation of the substructure of the state was, it will be observed, in an unusual degree, simple and progressive. Starting with a firm core of most ancient crystalline rocks, leaf upon leaf of stony strata were piled around it, adding belt after belt to the margin of the growing island until it extended itself far beyond the limits of our state, and coalesced with the forming continent. An ideal map of the state would show the Archaan nucleus surrounded by concentric bands of the later formations in the order of their deposition. But during all the

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HISTORY OF WISCONSIN.

vast lapse of time consumed in their growth, the elements were gnawing, carving and channeling the surface, and the outcropping edges of the formations were becoming more and more jagged, and now, after the last stratum had been added, and the whole had been lifted from the waters that gave it birth, there ensued perhaps a still vaster era, during which the history was simply that of surface erosion. The face of the state became creased with the wrinkles of age. The edges of her rocky wrappings became ragged with the wear of time .. The remaining Devonian periods, the great Carboniferous age, the Mesozoic era, and the earlier Tertiary periods passed, leaving no other record than that of denudation.

THE GLACIAL PERIOD.

With the approach of the great Ice Age, a new chapter was opened. An immense sheet of ice moved slowly, but irresistibly, down from the north, planing down the prominences, filling up the valleys, polishing and grooving the strata, and heaping up its rubbish of sand, gravel, clay and bowlders over the face of the country. It engraved the lines of its progress on the rocks, and, by reading these, we learn that one prodigious tongue of ice plowed along the bed of Lake Michi- gan, and a smaller one pushed through the valley of Green bay and Rock river, while another immense ice-stream flowed southwestward through the trough of Lake Superior and onward into Minnesota. The diversion of the glacier through these great channels seems to have left the southwestern portion of the state intact, and over it we find no drift accumulations. With the approach of a warmer climate, the ice-streams were melted backward, leaving their debris heaped promiscuously over the surface, giving it a new configuration. In the midst of this retreat, a series of halts and advances seem to have taken place in close succession, by which the drift was pushed up into ridges and hills along the foot of the ice, after which a more rapid retreat ensued. The effect of this action was to produce that remarkable chain of drift hills and ridges, known as the Kettle range, which we have already described as winding over the surface of the state in a very peculiar manner. It is a great historic rampart, recording the position of the edge of the glacier at a certain stage of its retreat, and doubtless at the same time noting a great climatic or dynamic change.

The melting of the glacier gave rise to large quantities of water, and hence to numerous torrents, as well as lakes. There occurred about this time a depression of the land to the north- ward, which was perhaps the cause, in part or in whole, of the retreat of the ice. This gave origin to the great lakes. The waters advanced somewhat upon the land and deposited the red clay that borders Lakes Michigan and Superior and occupies the Green bay valley as far up as the vicinity of Fond du Lac. After several oscillations, the lakes settled down into their present positions. Wherever the glacier plowed over the land, it left an irregular sheet of commingled clay, sand, gravel and bowlders spread unevenly over the surface. The depressions formed by its irregularities soon filled with water and gave origin to numerous lakelets. Probably not one of the thousands of Wisconsin lakes had an existence before the glacial period. Wherever the great lakes advanced upon the land, they leveled its surface and left their record in lacustine clays and sandy beach lines.

With the retreat of the glacier, vegetation covered the surface, and by its aid and the action of the elements our fertile drift soils, among the last and best of Wisconsin's formations, were produced. And the work still goes on.

BELOIT, Aug. 15, 1877.

CLIMATOLOGY OF WISCONSIN.

BY PROF. H. H. OLDENHAGE.

The climate of a country, or that peculiar state of the atmosphere in regard to heat and moisture which prevails in any given place, and which directly affects the growth of plants and animals, is determined by the following causes : Ist. Distance from the equator. 2d. Distance from the sea. 3d. Height above the sea. 4th. Prevailing winds; and 5th. Local influences, such as soil, vegetation, and proximity to lakes and mountains.

Of these causes, the first, distance from the equator, is by far the most important. The warmest climates are necessarily those of tropical regions where the sun's rays are vertical. But in proceeding from the equator toward the poles, less and less heat continues to be received by the same extent of surface, because the rays fall more and more obliquely, and the same amount of heat-rays therefore spread over an increasing breadth of surface; while, however, with the increase of obliquity, more and more heat is absorbed by the atmosphere, as the amount of air to be penetrated is greater. If the earth's surface were either wholly land or water, and its atmosphere motionless, the gradations of climate would run parallel with the latitudes from the equator to the poles. But owing to the irregular distribution of land and water, and the prevail- ing winds, such an arrangement is impossible, and the determination of the real climate of a given region, and its causes, is one of the most difficult problems of science.

On the second of these causes, distance from the sea, depends the difference between oce- anic and continental climates. Water is more slowly heated and cooled than land ; the climates of the sea and the adjacent land are therefore much more equable and moist than those of the interior.

A decrease of temperature is noticeable in ascending high mountains. The rate at which the temperature falls with the height above the sea is a very variable quantity, and is influenced by a variety of causes, such as latitude, situation, moisture, or dryness, hour of the day and season of the year. As a rough approximation, however, the fall of 1º of the thermometer for every 300 feet is usually adopted.

Air in contact with any part of the earth's surface, tends to acquire the temperature of that surface. Hence, winds from the north are cold; those from the south are warm. Winds from the sea are moist, and winds from the land are usually dry. Prevailing winds are the result of the relative distribution of atmospheric pressure blowing from places where the pressure is high- est, toward places where it is lowest. As climate practically depends on the temperature and moisture of the air, and as these again depend on the prevailing winds which come charged with the temperature and moisture of the regions they have traversed, it is evident that charts show- ing the mean pressure of the atmosphere give us the key to the climates of the different regions of the world. The effect of prevailing winds is seen in the moist and equable climate of West- ern Europe, especially Great Britain, owing to the warm and moist southwest winds; and in the extremes of the eastern part of North America, due to the warm and moist winds prevailing in summer and the Arctic blasts of winter.

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HISTORY OF WISCONSIN.

Among local influences which modify climate, the nature of the soil is one of the most important. As water absorbs much heat, wet, marshy ground usually lowers the mean tempera- ture. A sandy waste presents the greatest extremes. The extremes of temperature are also modi- fied by extensive forests, which prevent the soil from being as much warmed and cooled as it would be if bare. Evaporation goes on more slowly under the trees, since the soil is screened from the sun. And as the air among the trees is little agitated by the wind, the vapor is left to accumulate, and hence the humidity of the air is increased. Climate is modified in a similar man- ner by lakes and other large surfaces of water. During summer the water cools the air and reduces the temperature of the locality. In winter, on the other hand, the opposite effect is pro- duced. The surface water which is cooled sinks to lower levels; the warmer water rising to the surface, radiates heat into the air and thus raises the temperature of the neighboring region. This influence is well illustrated, on a great scale, in our own state by Lake Michigan.

It is, lastly, of importance whether a given tract of country is diversified by hills, valleys and mountains. Winds with their warm vapor strike the sides of mountains and are forced up into higher levels of the atmosphere, where the vapor is condensed into clouds. Air coming in con- tact, during the night or in winter, with the cooled declivities of hills and rising grounds becomes cooled and consequently denser and sinks to the low-lying grounds, displacing the warmer and lighter air. Hence, frosts often occur at these places, when no trace of them can be found at higher levels. For the same reason the cold of winter is generally more intense in ravines and valleys than on hill tops and high grounds, the valleys being a receptacle for the cold-air currents which descend from all sides. These currents give rise to gusts and blasts of cold wind, which are simply the out-rush of cold air from such basins. This is a subject of great practical impor- tance to fruit-growers.

In order to understand the principal features of the climate of Wisconsin, and the conditions on which these depend, it is necessary to consider the general climatology of the eastern United States. The chief characteristic of this area as a whole is, that it is subject to great extremes-to all those variations of temperature which prevail from the tropical to the Arctic regions. This is principally due to the topographical conditions of our continent. The Rocky mountains con- densing the moisture of the warm winds from the Pacific and preventing them from reaching far inland, separate the climate of the Mississippi valley widely from that of the Pacific slope. Between the Gulf of Mexico and the Arctic sea there is no elevation to exceed 2,000 feet to arrest the flow of the hot southerly winds of summer, or the cold northerly winds of winter. From this results a variation of temperature hardly equaled in any part of the world.

In determining the climates of the United States, western Europe is usually taken as the basis of comparison. The contrast between these regions is indeed very great. New York is in the same latitude with Madrid, Naples and Constantinople. Quebec is not so far north as Paris. London and Labrador are equi-distant from the equator ; but while England, with her mild, moist climate, produces an abundance of vegetation, in Labrador all cultivation ceases. In the latitude- of Stockholm and St. Petersburg, at the 60th parallel, we find in eastern North America vast ice- fields which seldom melt. The moist and equable climate of western Europe in high latitudes is due to the Gulf Stream and the southwest winds of the Atlantic, which spread their warmth and moisture over the western coast. Comparison, however, shows that the climate of the Pacific coast of North America is quite as mild as that of western Europe ; and this is due to the same kind of influences, namely, to the warm, moist winds and the currents of the Pacific. And to con- tinue the comparison. still further, in proceeding on both continents from west to east, or from ocean into the interior, we find a general resemblance of climatic conditions, modified greatly, it is true, by local influences.

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CLIMATOLOGY OF WISCONSIN.

The extreme summer climate of the eastern United States is owing to the southerly and southwesterly winds, which blow with great regularity during this season, and, after traversing great areas of tropical seas, bear the warmth and moisture of these seas far inland, and give this region the peculiar semi-tropical character of its summers. The average temperature of summer varies between 80° for the Gulf states, and 60° for the extreme north. While in the Gulf states the thermometer often rises to 100°, in the latitude of Wisconsin this occurs very seldom. During winter the prevailing winds are from the northwest. These cold blasts from the Arctic sea are deflected by the Rocky mountains, sweep down unopposed into lower latitudes, and produce all the rigors of an arctic winter. The mean temperature for this season varies between 60° for the Gulf coast and 15° for the extreme northern part of Wisconsin. In the northern part of the valley the cold is sometimes so intense that the thermometer sinks to the freezing point of mercury.

The extreme of heat and cold would give a continental climate if this extreme were not accom- panied by a profusion of rain. The southerly winds, laden with moisture, distribute this moist- ure with great regularity over the valley. The amount of rainfall, greater in summer than in winter, varies, from the Gulf of Mexico to Wisconsin, from 63 inches to 30 inches. On the At- lantic coast, where the distribution is more equal throughout the year on account of its proximity to the ocean, the amount varies, from Florida to Maine, from 63 to 40 inches. The atmospheric movements on which, to a great extent, the climatic conditions of the eastern United States depend, may be summed up as follows :

"I. That the northeast trades, deflected in their course to south and southeast winds in their passage through the Carribean Sea and the Gulf of Mexico, are the warm and moist winds which communicate to the Mississippi valley and the Atlantic slope their fertility.

" 2. That the prevalence of these winds from May to October communicates to this region a sub-tropical climate.

"3. That in the region bordering on the Gulf of Mexico, the atmospheric disturbances are propagated from south to north; but in the northern and middle states, owing to a prevailing upper current, from west to east.

"4. That while this upper current is cool and dry, and we have the apparent anomaly of rain storms traveling from west to east, at the same time the moisture supplying them comes from the south.

"5. That, in the winter, the south and southeast winds rise into the upper current, while the west and northwest winds descend and blow as surface winds, accompanied by an extraor- dinary depression of temperature, creating, as it were, an almost arctic climate.

"6. That the propagation of the cold winds from west to east is due to the existence of a warmer and lighter air to the eastward.

"7. That in summer the westerly currents seldom blow with violence, because, in passing over the heated plains, they acquire nearly the same temperature as the southerly currents, but in winter the conditions are reversed."

The line of conflict of these aerial currents, produced by unequal atmospheric pressure, shift so rapidly that the greatest changes of temperature, moisture, and wind, are experienced within a few hours, these changes usually affecting areas of great extent. In the old world, on the other hand, the mountain systems, generally running from east to west, offer an impediment, especially to the polar currents, and the weather is therefore not so changeable.

Wisconsin, situated in the upper and central part of the Mississippi valley, is subject to the same general climatic conditions which give this whole area its peculiar climate.

The highest mean summer temperature is 72º Fahrenheit in the southwestern part of the

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HISTORY OF WISCONSIN.

state, and the lowest 64° at Bayfield, Lake Superior. During the months of June, July and August, the thermometer often rises as high as 90°, seldom to 100°. In 1874 the mercury reachedL this high point twice at LaCrosse, and three times at Dubuque, Iowa. There are usually two or three of these "heated terms " during the summer, terminated by abrupt changes of temperature.

The isotherm of 70° (an isotherm being a line connecting places having the same mean tem- perature) enters this state from the west. in the northern part of Grant county, touches Madison, takes- a southerly direction through Walworth county, passes through southern Michigan, Cleveland, and Pittsburg, reaching the Atlantic ocean a little north of New York city. From this it is seen that southern Wisconsin, southern and central Michigan, northern Ohio, central Pennsylvania, and southern New York have nearly the same summer temperature. Northwestward this line runs through southern Minnesota and along the Missouri to the foot of the mountains. Eastern Ore- gon, at 47° 30' north latitude, has the same average summer temperature; the line then returns and touches the Pacific coast at San Diego.

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The History of Rock County, Wisconsin: Its Early Settlement, Growth, Development, Resources, Etc., Part 18

Author: Wesern historical company, Chicago, pub Publication date: 1879 Publisher: Chicago : Western Historical Co. Number of Pages: 899

Author: Wesern historical company, Chicago, pub
Publication date: 1879
Publisher: Chicago : Western Historical Co.
Number of Pages: 899