Rock County, Wisconsin - Chapter 1, 1879

Chapter 1

Topography - Elevations - Water Power or Eock River - Springs - Artesian Wells - Geologii'al FoiiMATioNS - St. Peter's Sandstone - Trenton Limestone - Galena Limestone - The Glacial Formations.

Topography

When Southeastern Wisconsin first emerged from the ocean, it doubtless presented an essentially plane surface, having a slight inclination to the east and southeast. The inequalities which it now presents are due to subsequent changes, the results of three classes of agents, acting at diiFerent times and under diiferent conditions.

1. During the long ages between the emergence of the land and the drift period, the streams were cutting their beds deeper and deeper into the rock, and rendering the former level surface more and more irregular. The softer rocks were more readily eroded than the harder ones, and this helped to increase the unevenness. There was a tendency of the streams, so far as the slope favored, to follow the less resisting belts of soft rock, and, as these run in a northerly and southerly course in this region, the main streams had that direction. The little streams gathered into the larger ones in a manner not unlike that by which the branches of a tree are united into the trunk. The unevenness of surface produced by erosion of this nature possesses a certain kind of system and symmetry readily recognizable. As this erosion occupied the time preceding the glacial period, we may conveniently designate the features produced by it, pre-glacial. We have the best example of this kind of surface conformation in the lead region, over which the drift forces did not act, and which has not been resubmerged, so that we have the results of this class of action pure and simple. As we proceed eastward into the region of drift action in the central part of the State, these features are modified more and more by the results of glacial action, until in Eastern Wisconsin they become wholly obscured, except in their grander outlines. Rock County lies midway between the extremes.

2. The modifications of the surface constituting this first class of topographical features were produced by running water ; those of the second class, which were formed next in order of time, were caused by ice, in the form of glaciers, it is confidently believed, and by the agencies brought into action through their melting. The work of the ice was twofold : first, in the leveling of the surface, by planing down the hills and filling up the valleys ; and second, in the creation of a new^ uneven surface, by heaping up in an irregular and promiscuous manner the clay, sand, gravel, and bowlders it had formed, thus giving the surface a new aspect. Among the features produced by the action of the ice, are parallel ridges, sometimes miles in length, having the same direction as the ice movement, hills of rounded flowing contour, sometimes having a linear arrangement in the direction of glacial progress, mounds and hummocks of drift promiscuously arranged on an otherwise plane surface, oval domes of rock {roches moutonees), sharp gravel ridges, often having a tortuous serpentine course, transverse to the drift movement, peculiar depressions known as "kettles," and half-submerged rock gorges, known as "fiords," all of which combine to form a peculiar and distinctive surface contour. The melting of the ice mass gave rise to swollen lakes and flooded rivers, which eroded at some points and filled up at others, and so still farther modified the face of the country. All these peculiarities, being the result, directly or indirectly, of the ice action, may be denominated glacial features.

3. Subsequent to the glacial period, the wearing action of the streams was resumed, but under somewhat new conditions, and carved out a new surface contour, the features of which may be termed post-glacial.

To the agencies, ice and water, assisted slightly by winds, the topographical peculiarities of the county are chiefly due. There is no evidence of violent eruptions, upheavals or outbursts. There was, indeed, the gradual elevation and depression of the surface, and probably some little flexure of the crust ; but the region has been free from violent agitation, and owes none of its salient topographical features to such causes.

Having thus briefly considered the general methods by which the present aspect of the county was produced, we may now more satisfactorily examine its special features.

No part of Wisconsin can properly be said to be mountainous, nor does it, over any considerable area, sink to a dead level. It presents the golden mean in a gently undulating, diversified surface, readily traversible in all directions by the various highways of communication.

Setting aside minor details, the State presents two general slopes - a short, abrupt declivity northward to Lake Superior, and a long, gentler incline southward. Through the center of this southward slope there extends a moderate north and south elevation, or arch - a low anticlinal axis - giving a southeasterly and southwesterly inclination to the strata on either side.

Rock County lies nearly on the summit of this low arch, or, to speak more exactly, its western line does ; while the rest of the county belongs to the eastern slope. The general inclination of the surface of the county is, however, decidedly southward. The valley of Rock River runs southerly through the center of the county, and at the point where it leaves the State is only about one hundred and fifty feet above the surface of Lake Michigan. The surface on either side of this valley slopes toward it. This includes all the county, except the southwestern corner, which drains into Sugar River.

In the immediate vicinity of Rock River there is an extensive plain, RockPrairie, three to five miles wide, with prolongations extending further back from the river at certain points. There is also a similar level area bordering Sugar River ; but with the exception of these and some minor areas, the surface of the county is gently undulatory or moderately rolling. At a few points facing the streams there are abrupt cliff's, but the amount of surface too steep for cultivation is very small.

Having disposed of the salient features of the topography of the Rock River Valley, attention is naturally directed to its minor characteristics. A consideration of these will be confined, in this connection, to Rock County. Among the most instructive are the elevations of different points. The figures indicate the altitude in feet above Lake Michigan. By adding 589 feet to those of any given point, the result will be the elevation above the ocean.

Township 1 North, Range 10 East {Avon). - Section 5, northeast quarter, 272 feet ; Section 5, southeast quarter, stream, 192 feet ; Section 9, southwest quarter, 320 feet ; Section 13, southwest quarter, 327 feet ; Section 18, bottom of Galena limestone, 380 feet ; Section 18, southeast corner, 318 feet ; Section 22, southwest quarter, 245 feet ; Section 25, southwest quarter, slough, 171 feet.

Township 2 North, Range 10 East {Spring Valley). - Oxford Station, 313 feet ; Section 2, middle, east line, 850 feet ; Section 3, north line of northeast quarter, 418 feet ; Section 3, southeast quarter, 834 feet ; Section 3, southwest quarter of southwest quarter, 314 feet ;

Section 4, northwest quarter, stream 291 feet ; Section 4, 338 feet ; Section 4, southwest quarter, flat, 253 feet ; Section 4, southeast quarter of southeast quarter. 352 feet ; Section 9, center, 321 feet; Section 11, northeast quarter, 423 feet; Section 11, southwest quarter, 342 feet; Section 11, hill, 396 feet ; Section 12, center, north half, 389 feet ; Section 12, southeast quarter, flat, 288 feet ; Section 12, outcrop, 301 feet ; Section 13, middle, north line, 300 feet ; Section 15, southeast quarter, 321 feet; Section 17, southeast quarter, stream, 215 feet; Section 18, southeast quarter, Taylor's Greek, 204 feet ; Section 19, northwest corner, 220 feet ; Section 21, northeast quarter of northwest quarter, railroad, 236 feet ; Section 24, east line of southeast quarter, 405 feet ; Section 28, northeast quarter, 296 feet ; Section 33, southeast quarter, 268 feet ; Section 34, northwest quarter. Galena limestone, 345 feet ; Section -34, northwest quarter, summit, 394 feet ; Section 34, south line southwest quarter, 336 feet.

Township 3 North, Range 10 East {Magnolia). - Magnolia Station, 340 feet ; Section 6, middle, west line, northwest quarter, 354 feet ; Section 6, middle, west line, 285 feet ; Section 6, southwest quarter, flat, 286 feet ; Section 6, southwest quarter, 309 feet ; Section 6, southwest quarter, Allen's Creek, 278 feet; Section 6, southeast quarter, 860 feet; Section 7, southeast quarter, 483 feet ; Section 7, southeast quarter, road, 323 feet ; Section 7, southeast quarter, top of ledge, 450 feet ; Section 9, northwest quarter, Allen's Creek, 292 feet ; Section 23, northwest quarter, 339 feet ; Section 26, southwest quarter, 884 feet ; Section 26, southwest quarter, summit, 441 feet ; Section 28, southwest quarter, 339 feet ; Section 84, northwest quarter, 432 feet.

Township 4- North, Range 10 East (Union). - Evansville Station, 326 feet; Section 1, northwest corner, 321 feet; Section 1, northeast quarter of northeast quarter, mill, 238 feet; Section 2, northwest corner, 836 feet ; Section 2, northwest quarter, 339 feet ; Section 2, northwest quarter, stream, 288 feet; Section 4, northwest quarter, 379 feet; Section 5, northeast quarter, 379 feet; Section 6, northwest corner, railroad, 400 feet; Section 6, west half, marsh, 377 feet; Section 6, southwest corner, 427 feet; Section 7, northwest quarter, 442 feet; Section 10, west half Union village, 875 feet ; Section 12, northwest quarter, hill, 412 feet ; Section 12, near center, 298 feet; Section 13, northwest quarter, stream, 293 feet; Section 14, center, east half, 339 feet; Section 18, middle, west line, stream, 882 feet; Section 18, southwest quarter, flat, 368 feet ; Section 19, southwest (quarter, 891 feet ; Section 19, northwest corner, 882 feet ; Section 22 (est.), 407 feet ; Section 26, southeast quarter, 334 feet ; Section 26, near northeast corner, 889 feet; Section 29, center south half, flat, 367 feet; Section 30, southeast quarter, well, 402 feet ; Section 80, southwest quarter, valley, 345 feet ; Section 30, near center, west line, 836 feet; Section 81, northeast quarter, 383 feet; Section 31, northeast quarter, summit, 423 feet; Section 81, southwest quarter, 290 feet; Section 33, near center, stream, 352 feet; Section 84, near northwest corner, 400 feet.

Township 1 North, Range 11 East [Newark). - Section 1, northeast quarter, spring, 258 feet ; Section 1, southwest quarter, 362 feet ; Section 3, northwest quarter, 328 feet ; Section 10, middle west line, 342 feet; Section 11, southwest qu^irter, 357 feet; Section 11, southwest quarter, hill, 879 feet; Section 18, west line, near middle, 818 feet; Section 18, southeast corner, 263 feet; Section 13, southeast quarter, flat, 193 feet; Section 14, northwest quarter, 305 feet ; Section 14, southwest quarter, 331 feet ; Section 15, southwest quarter, stream, 296 feet ; Section 16, southeast corner of southwest quarter, 244 feet ; Section 16, southwest quarter, Coon Creek, 183 feet; Section 20, middle south line, ridge, 318 feet; Section 24, northeast quarter, stream, 196 feet; Section 25, center west half, 252 feet; Section 25, southeast quarter, 274 feet ; Section 28, northeast quarter, creek, 190 feet ; Section 29, northeast quarter, quarry, 222 feet; Section 31, center east half, 222 feet; Section 31, near center, 263 feet; Section 3l', west of center, 275 feet ; Section 81. west half, 249 feet ; Section 82, center, 281 feet ; Section 33, near center, 207 feet ; Section 33, middle west line, 220 feet ; Section 33, bottom of outcrop, 245 feet ; Section 34, center ridge, 207 feet ; Section 35, center, creek, 144 feet.

Township 3 North, Range 11 East [Plymouth). - Hanover Junction, 209 feet ; Section 1, southwest quarter, 261 feet ; Section 9, northeast corner, railroad, 225 feet ; Section 28, middle west line, 895 feet; Section 33, northeast corner, 342 feet; Section 35, middle west line, 412 feet.

Township 3 North, Range 11 East {Center). - Section 9, stream and marsh, 293 feet; Section 16, northeast quarter, 363 feet ; Section 16, center, 364 feet ; Section 20, northwest quarter, 400 feet ; Section 21, center, northwest quarter, 389 feet ; Section 32, northeast quarter, 354 feet ; Section 33, northwest corner, 339 feet ; Footville Station, 238 feet.

Township 4 North, Range 11' East {Porter). - Section 1, northeast corner, 284 feet; Section 3, northeast quarter. Catfish River, 196 feet ; Section 3, north line, northwest quarter, 265 feet ; Section 3, southwest quarter, stream, 196 feet ; Section 5, northeast corner, 247 feet ; Section 5, middle north line, northwest quarter, 261 feet; Section 6, middle east line, 261 feet; Section 9, northwest quarter,- 250 feet ; Section 9, middle east line, northeast quarter, 260 feet.

Township 1 North, Range 12 East {Beloit). - Section 3, southwest quarter of southwest quarter, 196 feet ; Section 6, near center west line, 200 feet ; Section 6, southwest corner hill, 309 feet ; Section 10, east line, northeast quarter, 152 feet ; Section 10, northeast quarter, 180 feet; Section 10, near center, 273 feet; Section 10, southeast quarter, 200 feet; Section 10, south line, southeast quarter, 302 feet ; Section 17, near center, 314 feet; Section 17, northwest quarter, 228 feet; Section 18, southeast corner, 225 feet; Section 18, south line, hill, 260 feet; Section 19, center west half, 264 feet ; Section 26, northwest quarter, 193 feet ; Section 27, near center, 197 feet; Section 28, middle south line, 251 feet; Section 28, Hyde's place, 233 feet ; Section 28, summit, Hyde's, 276 feet ; Section 29, northeast quarter, creek, 189 feet ; Section 30, southeast corner, 167 feet ; Section 31, center, creek, 144 feet ; Section 33, middle west line, 210 feet ; Section 34, northwest quarter, Hanchett's quarry, 213 feet ; Section 34, southeast quarter of northwest quarter, 201 feet ; Section 34, middle west line, 236 feet ; Section 35, southeast quarter, 161 feet ; Section 36, near center, southeast quarter, 176 feet ; south line College Campus, 192 feet ; lodo-Magnesian Springs, 177 feet.

Township 2 North, Range 12 East {Roch). - Afton, 206 feet ; Section 7, northeast quarter, summit, 306 feet ; Section 8, northwest quarter, railroad, marsh, 265 feet ; Section 20, middle west line, Bass Creek, flat, 183 feet ; Section 21, middle west line, 206 feet.

Township 4 North, Range 12 East {Fulton). - Newville bridge, 208 feet'; Edgerton Station, 242 feet; Section 3, center north line, 251 feet; Section 4, center north half, 232 feet; Section 5, center south line, 173 feet; Section 5, sou^h line, southeast quarter, 284 feet; Section 6, northwest quarter, 240 feet; Section 10, southwest quarter, 219 feet.

Township 1 North, Range 13 East {Turtle). - Crest of hill, east of Beloit, 405 feet; Section 5, level. Rock Prairie, 217 feet ; Section 9, northeast quarter, 227 feet ; Section 9, northwest quarter of southeast quarter, 225 feet ; Section 13, southeast quarter, 330 feet ; Section 13, middle south line, southwest quarter, 306 feet; Section 15, northeast corner, 222 feet; Section 16, center, 223 feet; Section 19, center, 202 feet; Section 21, middle south line, 228 feet; Section 22, northwest quarter, 270 feet; Section 22, northeast quarter, 280 feet; Section 22, north half, near railroad cut, 302 feet; Section 22, bottom of Galena exposure, 246 feet; Section 22, summit of hill, 276 feet; Section 23, northeast quarter, 280 feet; Section 28, middle east line, 325 feet ; Section 29, near center, 218 feet ; Section 31, northeast corner, 211 feet ; Section 31, north of center, 188 feet ; Section 32, center north half, 229 feet ; Section 33, northeast corner, 266 feet.

Township 4 North, Range 13 East {Milton). - Milton Station, 293 feet; Milton Junction, 299 feet; ridge south of Milton Junction, 318 feet; Section 10, southeast corner, 216 feet; Section 22, center east half, hill, 375 feet ; Section 25, southeast quarter, 307 feet ; Section 26^ southeast quarter, 303 feet ; Section 30, northeast quarter, 289 feet ; Section 30, northwest quarter, 255 feet.

Township 1 North, Range I4. East {Clinton). - Section, 2, east half, 370 feet ; Section 2, southwest quarter, 352 feet; Section 9, center, 873 feet; Section 10, northwest quarter, 362 feet ; Section 17, Clinton Junction, 364 feet ; Section 18, northeast quarter, 338 feet.

Township ^ North, Range ll East [Lima). - Section 6, southeast quarter, marsh, 243 feet ; Section 13, northeast quarter, 307 feet ; Section 14, southeast quarter, 316 feet ; Section 18, near middle west line, 248 feet ; Section 21, southeast corner, 301 feet ; Section 22, Lima Station, 310 feet; Section 23, middle north half, 305 feet; Section 23, west line, 308 feet; Section 30, east line, 311 feet.

Water Power Of Rock River

The entire area drained by Rock River and its tributaries in Wisconsin is three thousand six hundred and thirty-five square miles. From the Table of Rainfall, at Milwaukee, given in Dr. Lapham's report (Geol. of Wis., Vol. II), it appears that the average rainfall for the thirty years previous was 30.27 inches, which may be assumed as at least approximately cOTrect for the Rock River Valley. The average fall for some portions of Wisconsin is given in Gen. Humphrey's work on the hydraulics of the Mississippi, at thirty-five inches. But reckoning at thirty inches, the rainfall upon the drainage area under consideration, would be 253,344,960,000 cubic feet. Now, it is asserted by various authorities, based on experience, that one-half the rainfall can be utilized. This would give 126,672,480,000 cubic feet per annum. Mr. Ruger says : " From personal observation, and after consulting many authorities as to rainfall, springs, evaporation, filtration, etc., I estimate that the total annual quantity of water passing in Rock River at the State line, including Turtle Creek, is 98,437,536,000 cubic feet," which may be regarded as a safe estimate. The daily suppljs by this estimate would be 269,691,879 cubic feet. We need next to ascertain what is the average descent of this volume. Some of it falls over six hundred feet, while other portions practically no distance. The average elevation of the rim of the basin above the point where the river leaves the State is about two hundred and fifty feet, its average distance about fifty miles, showing an average fall of about five feet per mile. But this is less to' the point than the following :

The average elevation of fifteen powers, the first of importance on their respective branches, is about one hundred and fifty-five feet above the surface of the river where it leaves the State at Beloit. The average fall from these powers to the State line is a little less than three feet per mile.

With these general statements, we will set aside the tributaries, several of which are important, and consider more accurately the main stream between Horicon and Beloit. The collecting area above Horicon is four hundred and thirty-six square miles, upon which the annual rainfall, reckoned at thirty inches, would be 30,387,456,000 cubic feet. Allowing one-half for evaporation, filtration and other sources of loss, the theoretical discharge at the outlet of Horicon Marsh would be 15,193,728,000 cubic feet. Reckoned at the lowest rainfall in the last thirty years, the amount would be 10,114,749,120 cubic feet. Col. Worrall gives, as the result of a careful measurement of the flow at a time when the volume was estimated to be only three-fourths of the average, a supply of 27,651 cubic feet per minute, or 14,533,365,600 cubic feet per annum, from which it would seem that the calculated amount is not far from the truth. From the foregoing data, .estimating the accession from tributaries, it is thought to be safe to consider the average flow between Horicon and Beloit, as, in round numbers, 60,000,000,000 cubic feet per annum. The fall from Horicon to the State line is one hundred and twenty-seven feet. An estimate of the theoretical power generated by the main river shows it to be upward of 20,000 horse power. Of the one hundred and twenty-seven feet fall, less than sixty feet are utilized, according to the best information at command. The unused portion is mainly between Horicon and Watertown, and between Janesville and Beloit. A portion of this latter may readily be made available at Beloit by means of a race leading from a dam situated above the

Roek County, in common with other portions of Eastern Wisconsin, has two general systems of springs - those that originate in the drift deposits, and those that flow from the rock. The springs of each group occupy several difi'erent horizons, which it will be interesting to notice briefly, as the subject is one of great importance, it having been abundantly demonstrated that some of the most terrible diseases which afflict mankind are directly attributable to impure water. If unaided nature has provided any means of escape from this prolific source of danger, it is certain to be found in her deep-seated springs.

There are several reasons why spring-water is more likely to be pure than that of wells. On the average, it comes from greater depth, and has passed through a greater extent of the deeper strata, which are comparatively free from organic impurities, than has the water of wells, which is usually drawn from the surface of the water level beneath the location of the wells. Artesian fountains are not here taken into account. ' The water of wells is usually stagnant, while that of springs is active - is "living water." There are some exceptions to the first part of this statement. Occasionally a well is sunk upon an active, flowing, underground stream, in which case the superior character of the water will usually be very marked. Spring-water is not liable to so many sources of contamination, and accidental impurities are more readily discharged.

The lowest noteworthy horizon from which springs arise, is the vicinity of the junction of the Potsdam sandstone and the Lower Magnesian limestone. The water from this source usually has a temperature of forty-eight to fifty degrees, and is clear and comparatively free from organic impurities, but contains a small percentage of the carbonate of lime and magnesia, and, in some cases a very small percentage of iron, with usually some sUica, alumina and chloride of sodium. But the combined amount of these is small, and the water is "soft," and very pleasant to the taste. A small amount of free carbonic acid is usually present, which enhances the grateful effect of the water upon the palate and stomach. There are no springs from this horizon in the county, but the water-bearing bed may be reached by wells.

Above this horizon, springs occur but rarely till we reach the junction of the St. Peter's sandstone with the Trenton limestone. Some shaly impervious layers mark this division, while the limestone above is fissured and the sandstone below is porous. It hence follows that the springs may arise either above or below the impervious stratum, according to circumstances. (1) Water descending from above may be caught and carried out where the strata are cut across to the proper depth ; and (2) water that gained access to the sandstone at some distant and more elevated point may rise from below at places where the confining stratum is removed. So that it is proper to include in this group some that issue from ledges somewhat above or below the junction of the formations. These springs are similar in general character to the last, but usually contain a more considerable percentage of the several mineral ingredients, at least that portion of them that are derived from the limestone, which still retains traces of many of the salts that we have reason to suppose were incorporated with it when it was formed beneath the ancient ocean. To this class belong most of the springs that issue from the rock in the western half of Rock County]; those that issue from the rock in the eastern half spring from the Galena limestone.

The foregoing are all derived from rocks that were laid down under the ancient Silurian ocean, rocks whose ages are to be reckoned by myriads of years, and from which there has at least been a liberal allowance of time for the removal of whatever soluble matter may have been originally incorporated in them ; and yet we find in all that have been analyzed varying quantities of the oceanic salts.

The remainder issue from loose material of much more recent origin, formed by the agency of ice and fresh water, so far as the evidence goes ; and yet, as this material was derived from the preceding oceanic formations in great part, the same ingredients may and do occur in the water. They are, as a class, more superficial than the preceding, and more liable to contamination from surface impurities, and for a like reason their temperature is often less constant and their flow less regular. To this class belong those springs that issue from the drift.

The most remarkable and most valuable springs in Rock County are the lodo-magnesian, at Beloit, which flow from the lower portion of the Trenton limestone, and give this analysis :

Artesian Wells

The term artesian is frequently applied to deep wells, without regard to whether the water flows at the surface or not ; but it will here be confined to flowing wells, without regard to depth. Flowing wells depend upon these requisite conditions : There should be an impervious stratum to prevent the escape of the water below ; a previous water-bearing stratum upon this, .to furnish the flow of water ; a second impervious layer upon this, to prevent the escape of the water above, it being under pressure from the fountain-head. These must dip, and there must be no adequate outlet for the water at a lower level than the well. There must also be a sufficient collecting area or reservoir in connection with the porous stratum, and it must have suflScient elevation to act as a fountain-head.

Wells of this description in Eastern Wisconsin are divided into six different classes, only one of which is now found in Rock County, though there is every reason to believe that others could be sunk successfully in some portions of the county.

The well on the fair grounds at Janesville belongs to the class which flow from the primordial zone. The flow of this well at the surface is obtained only by the aid of hydraulic appliances. The elevation is about two hundred and ninety-five feet above Lake Michigan, and the depth is one thousand and thirty-three feet, through the following formations :

Probably forty to fifty feet of the upper portion of the Potsdam has been removed, making the thickness about seven hundred and twenty-five feet, with the bottom not reached. In the upper portion of the Potsdam horizon, a vein was struck which gave a permanent rise in the tube of forty-eight feet above the water level in the open well, without the aid of a seed-bag or other apparatus for preventing lateral leakage. This corresponds, according to aneroid measurement, to two hundred and forty-seven feet above Lake Michigan, or seven feet above the depot at Janesville.

There are three extensive areas in Eastern Wisconsin over which there is a reasonable presumption that fountains may be obtained, one of which lies in the Rock River Valley. An elevation of two hundred feet should be taken as the upper limit of favorable chances, and the Janesville well shows that a flow may be obtained at this altitude.

As a majority of deep-seated wells of Eastern Wisconsin derive their flow from the St. Peters sandstone, the following list, showing the elevations in Rock County at which the upper face of that formation outcrops is submitted : Avon, Section 5, northeast quarter, 272 feet ; Section 9, northeast quarter, 250 feet ; Beloit, Section 3, southwest quarter, 229 feet ; Section 3, southwest quarter of southwest quarter 196 feet ; Section 10, northeast quarter, 180 feet ; Section 10, southeast quarter, 200 feet ; Fulton, Newville bridge. Rock River, 208 feet ; Magnolia, Section 6, southwest quarter, 309 feet ; Section 7, southeast quarter, 433 feet ; Section 28, southwest quarter, 339 feet ; R. R. Cut, 330 feet ; Porter, Section 9, northwest quarter, 250 feet ; Rock, Section 32, 189 feet ; Afton, 206 feet ; Spring Valley, Section 3, southwest quarter of southwest quarter, 314 feet ; Section 4, southwest quarter of southwest quarter, 338 feet ; Section 9, center, 321 feet ; Section 13, Mid. N. line, 300 feet ; Section 15, southeast quarter, 321 feet; Section 28, northeast quarter, 296 feet; Section 33, southeast quarter, 268 feet ; Union, Section 12, near center, 298 feet.

Geological Formations

The northern part of the State is occupied by the oldest formations that are definitely known to geologists by observation, though theoretically there are older ones. These dip down beneath the sandstones and limestones that constitute the upper formations in the southern part of the State. They pass beneath Rock County at a depth of more than a thousand feet, and may be looked upon as forming the great rock floor upon which the later formations repose. There lies upon this floor first, a great bed of sandstone, to which the name Potsdam has been given. The thickness of this is somewhat irregular, but is sometimes nearly, or quite one thou- sand feet. It does not appear at the surface anywhere in the county, but was penetrated by the Janesville artesian well. Upon this sandstone there, lies the Lower Magnesian limestone. ' This is likewise irregular in thickness, varying in Eastern Wisconin from about sixty feet to one hundred and fifty feet, while in the western part of the State it is sometimes two hundred and fifty feet thick. It does not appear at the surface within the county, but would in the northern part if the drift - the sand, gravel and clay - were removed.

St. Petees' Sandstone

Upon the Lower Magnesian limestone, there rests the St. Peters sandstone, which is also uneven in thickness, the average being, perhaps, seventy-five to one hundred feet. This may be readily recognized, as it is the only sandstone known to crop out in the county. It may be seen to good advantage in the clifis that face the Sugar River Valley, in the western part of the county, and along the valleys of the streams that lead down into it, particularly along Allen's Creek, in the town of Magnolia. It may be seen in the north part of the railroad cut, near Magnolia Station, where it is overlaid by the Trenton limestone, the junction between the two being well shown. It also appears in the cuts between Magnolia and Footville, and forms that singular natural monument not far from the track, about midway between the two stations, which attracts so much attention from passengers on the Chicago & North Western Railway This railroad cuts through the formation again just below Afton, where the Trenton limestone may also be seen to advantage overlying it. Both formations appear along Bass Creek, above this.

It is also exposed at several points around the base of the " Big Hill," north of Beloit, and at the quarries along the railroad below. The lower quarry is the most southerly point at which it is known to appear at the surface in the Rock River Valley. It dips southeastward, and becomes buried by later formations. Following up Rock River, we again find the St. Peters sandstone at several points above and below Janesville in the banks of the river. It is well exhibited near the Monterey bridge, and forms that singular little promontory above the dam on the right-hand side of the river. This sandstone may also be found near Indian Ford, and above along the river ; likewise along the creek below Edgerton, and at several other points in the county. It should be understood that it is a nearly horizontal bed, underlying nearly all the county, and that it is only where the valleys have cut down into it that it is exposed to view. In other portions, it is covered by later formations, but may be reached by wells. It is everywhere a soft, crumbling standstone, usually white or yellow, but sometimes red or green. It furnishes an excellent building sand, and some portions are suited to glass manufacture. In the upper portion, there are often concretions of iron ore. The constituent grains of sand are nearly pure quartz.

Tebnton Limestone

Upon the St. Peters sandstone, there lies the Trenton limestone. This is the limestone so frequently seen in the western half of the county ; indeed, with the exception of the capping of several of the higher hills with Galena limestone, it is the only limestone that outcrops west of Rock River.

It has been divided by the State Geologist into four subdivisions, which will be found fully described in his geological reports ; but it may be diificult for a non-professional observer to always discriminate between them. The subdivisions are the Lower Buff, the Lower Blue, the Upper Buff and the Upper Blue beds. All of these beds are more or less buff near the surface, so that the color is not a wholly reliable guide.

In the vicinity of Beloit, there are a number of natural and artificial exposures that are so fortunately situated at different elevations as to exhibit the entire thickness of the formation, and yet - an equally fortunate circumstance for the students of geology of that locality - their correct correlation is attended with something of difficulty, and is only accomplished by careful and industrious study. By combining the partial series shown at the various points, the following general section for that vicinity may be constructed, and may be taken as illustrative of the general nature of the formation :

Upper Blue Beds. - A greenish-blue impure limestone, chiefly earthy and subcrystalline, but in part granular, beds thin and separated with shale, very fossiliferous. Estimated thickness, 15 feet.

Upper Buff Beds. - I. In general, a fine-grained, impure limestone of earthy or subcrystalline texture, the former a light bijff, the latter gray, combined so as to give an obscure banded and mottled appearance quite peculiar. Nodules of chert are present, which distinguish it from the rock below. Beds, thick and uniform, fracture easy and regular in the upper two-thirds, while that of the lower part is very rough and angular, as though from a brecciated structure ; more impure than the upper portions. A shaly layer, seven feet from the base, contains carbonaceous seams, with graptolite markings. Thickness, 22 feet.

II. Layer of homogeneous structure, conchoidal fracture and earthy texture, but sparkling with minute crystals ; lined and spotted with obscure reddish fucoidal stains. Thickness, 2^ feet.

III. Combines to some extent the character of the layers above, being less homogeneous than the last, and more so than the preceding. Some layers, very fossiliferous, the remains being^ grouped more or less in colonies. Horizon of the Halysites. Thickness, 7 to 8 feet.

Lower Blue Beds. - Thin-bedded, impure limestone of varying earthy and crystalline texture, interleaved with shaly partings, the whole having a bluish-green or gray color ; very fossiliferous, 20 feet.

Lower Buff Beds. - Thick-bedded, buff limestone, ,of rather coarse texture, somewhat shaly at the base. Fossils not very abundant, except in the shaly portions, 23 feet.

B18 History Of Rock County

In the vicinity of Janesville there are several quarries and cliifs that exhibit this formation. At the lower railroad bridge the Lower Buif beds are seen reposing upon the St. Peters sandstone, and above these the Lower Blue beds, which are here quite shaly. At the quarry one and a half miles west of the city we find at the base the heavy Buff beds, above which are the Lower Blue beds, and at the top the Upper Buff beds. Above the city, the river road on the side winds up through a little defile between cliffs composed of the middle portion of this formation. On the west side of the river and farther up on both sides, the lower beds of the formation are seen reposing on the sandstone. This locality presents a fine field for the young student of geology.

The railroad cuts mentioned in connection with the St. Peters sandstone and the cliffs in the western part of the county expose to view the lower layers of this formation. The cliffs in almost all cases owe their origin to the protecting cap of Trenton limestone. The soft sandstone is readily worn away from beneath, leaving a projecting ledge or vertical cliff.

This limestone forms a stratum which slopes gently to the southeast, so that in the eastern part of the county it becomes entirely buried by later formations. There are no cliffs or quarries in it east of Rock River, except in the immediate vicinity of the stream and some slight exposures of the upper layers near Turtleville. The formation is valuable for lime and building material.

The Galena Limestone

Upon the Trenton limestone there rests a closely related formation known as the Galena limestone, from the fact that it is the main formation that bears galena or lead ore in the lead region of the southwestern part of the State. It differs from the Trenton limestone in being thicker bedded and having a more irregular texture, so that it weathers into rough, craggy forms, and often has a rotten appearance. It is usually a deeper buS than the Trenton beds.

In the western part of the county, it is only found on the higher elevations, forming a cap of no great thickness to some of the hills and ridges. In the eastern part of the county, it is more extensively prevalent, though largely concealed by. drift. It may be seen in the quarry south of Milton, in those near Emerald Grove, and, very finely, along the gorge of the Turtle Creek, in Bradford, and along the railroad above Porter's Station in the town of Turtle. At these points it has essentially the same appearance that it presents in the lead region, but only small quantities of lead ore have ever been found in this portion of the formation.

The Glacial Formations Or Drift

Long after the above formations had been deposited by the Silurian ocean, and had been lifted from the water and eroded into hills and valleys by the elements, the region was subjected to the action of ice and glacial waters, by which a covering of clay, sand, gravel and bowlders was deposited over the face of the region, well-nigh concealing all the strata beneath. This constitutes the drift, or glacial, or quaternary deposits that prevail at the surface. They are composed of rounded fragments and the ground-up material of various kinds of rocks. When carefully studied, it is found that all these fragments were derived from formations lying to the northward and northeastward, and that a great many of them came from the Lake Superior region and beyond, as, for instance, the copper that is occasionally found, sometimes in quite large lumps.

Taken altogether, this is one of the most puzzling formations known to geologists ; and although the explanations worked out by the recent geological survey are probably the most satisfactory that have ever been given, it would far transcend our limits to attempt to reproduce them here. Indeed, we can only very briefly mention some of the more prominent facts.

In the southwestern part of the county, the drift is not very deep in general, and the shape of the hills and valleys is mainly determined by the contour of the underlying rock, which frequently shows itself in the side hills.

But across the northern part of the county there is a belt of very heavy drift, which gives an irregular, billowy, knob-and-basin contour to the surface. The most prominent part of the belt curves across the county from east to west, passing south of the villages of Lima, Milton, Fulton and Cooksville, and lying between the latter place and Evansville.

This is part of a very extensive drift ridge, or rather belt of ridges, that has been traced by the State Geologist in its windings, not only across our State, but into adjoining States, and has been called by him the Kettle Moraine, it being a part of the Kettle Range of Eastern Wisconsin.

There are some minor drift ridges that possess interest, especially one in the town of Beloit. The great gravel plain of the Rock River Valley, and the similar plain of the Sugar River Valley, are interesting subjects of study to the geologist. The drift of the former, as shown by the artesian well at Janesville, is 350 feet deep. It probably fills an ancient river chaanel.

The soil, the latest geological formation, was produced by the disintegration of the drift and of the rock, where it approaches the surface.