Imagens das páginas
[ocr errors]

for rails from Ent nate

To incidental causes alone, and not to any natural deficiency of material, must be attributed the custom of importing annually from England, into this country, millions of dollars worth of iron for railroads and other purposes. Enormous as is the produce of Great Britain's iron-furnaces, (amounting, in 1833, to fifteen hundred millions of pounds,) we might rival it in America. How little here in the west, at least, we have hitherto improved our natural resources in this branch of commerce, is proved by the thousands of tons of rich iron ore which lie, unappropriated and useless, scattered over the Territories of Iowa and Wiskonsin.

ere indred mill Great


An inspection of chart No. 3 will show how the great coal-field of Illinois extends its northwestern margin over ten or twelve townships of the district, chiefly on the western side of the Mississippi.

One seam of coal only was discovered cropping out west of the Missis. sippi ; and that was of indifferent quality, lying in the north half of section twenty-seven, township seventy-eight, range four east of the fifth principal meridian, on Duck creek. Several were found in the tongue of land which lies in the fork between Rock river and the Mississippi: one of them from five to six feet in thickness. The quality of this last is fair; and, in proportion as the coal-diggings extended, the quality improved.

Several good seams of coal show themselves south of the district, within a short distance of its southern boundary; and there is no doubt that any required quantity of this fuel may be procured at no great distance from the mouth of Rock river, which stream enters the coal-field about 23 miles above its mouth, and has several good seams exposed in the banks.

* An analysis of two average specimens of coal-one from Duck creek, the other from the eastern bank of the Mississippi, near the mouth of Rock river-resulted as follows:

Examination of the Duck-creek coal, from northwest quarter of section tirenty-seven noTLA, TGAGE

four east, of the fifth principal meridian: two feet exposed. Specific gravity

Volatile matter

Carbon in coke
Yellow ashes




100 grains of nitrate of potash required 24 grains of this coal for complete decomposition. Calculating the amount of pure carbón necessary to decompose 100 grains of the same mitre at 12 grains, this would indicate about 50 per cent. of carbon, and leave about 42.5 of bitumen and volatile gasses.

Examination of the Rock-river coal.
Specific gravity . . . . . . . .34

Volatile matter
Carbon in coke
White ashes



100 grains of nitrate of potash required 34 grains of this coal for complete decomposition, indicating about 50 per cent, of charcoal, and about 30 per cent, of bitumen. This coal re sembles the slaly cannel coal in its composition.

The coal in this vicinity is sure to become valuable, and to be in great demand, for the reduction of such ores (especially copper ores) as are raised in those portions of the district which are deficient in timber. Some town in this neighborhood, or a little farther south, is destined to become the Swansea of Wiskonsin, and to receive, in its numerous furnaces, the rich produce of the prairie mines from the north and north west.

SILINES. Throughout the western States generally, no productive salines are found below the true coal-measures. They commonly occur in some of the lower members of the coal formation, especially in the white sandstones lying within that formation, and at no great distance from its margin. Such are the well-known saliferous rocks on the Kenhawa and Muskingum.

As soon, therefore, as the character and extent of the geological formations in the district were ascertained, I ceased to expect the discovery of any productive salines, except, perhaps, in the extreme southern corner of the tract, where the great coal field of Illinois stretches its lowest members over a few townships.

Every surface-indication confirmed my expectations. No salt-springs, not a single salt-lick, no variegated shales, not one of the usual indications of salt, were discovered. Even in the southern townships, within the coalformation, the thickness of the strata is so inconsiderable that the chance is very slender of reaching profitable brine. Salt, therefore, cannot be reckoned among the productive minerals of Iowa and Wiskonsin. It may, probably, be obtained along the head-waters of the western and northeastern tributaries of the Illinois river.

BUILDING STONE. I was for a time in doubt in regard to the value of the Wiskonsin linestone as a building material. Where it has numerous nodules of chert distributed throughout its mass, it weathers unequally, the nodules become detached, and its beauty and value as a building rock is much lessened. This occurs chiefly in the superior portion of the upper beds; that is, over the southern portion of the surveyed district.

Much of the limestone that is taken from the diggings crumbles, also, on being exposed to the weather; yet a portion of the formation will yield some of the best quarries in the world, and several excellent ones are already opened ; for example, on the Sinsinnewa mound, at Mineral Point ; at the Four Lakes; and (but not so good) on the Peccatonnica. This excellent building stone chiefly occurs in the lower portion of the upper beds of the cliff limestone, and, also, in the lower beds of the “Missouri limestone." It is of a beautiful uniform light yellow color, compact, finegrained, sharp-angled, capable of receiving a handsome finish, and, if well selected, calculated to endure, uninjured, for ages. It is very readily quarried in square blocks from six inches to a foot in thickness ; can be obtained, however, double or treble that thickness, and of any required horizontal extent. The labor of quarrying is light, in consequence of the rock being exposed in cliffs so as to preclude the necessity of excavation.

In a recent geological notice from England, it is stated that Mr. De la Bèche, in conjunction with Mr. Barry and the veteran father of English geology, (William Smith,) had been intrusted by the British Government

[ocr errors]

lande experienced geologestone of Yorkshire old churches of i texture, ar

with the care of selecting the material of which the new houses of Parliament were to be constructed ; and after a tour, made in the course of last year for this express purpose, to the points where the best building stones were supposed to be quarried, they made choice of the magnesian linnestone of Yorkshire, remarkable for the durability of its color, texture, and sharpest forms, as exemplified in the noble old churches of that country. But ihis magnesian limestone of Yorkshire, thus selected by some of the most experienced geologists in the world as the best building stone in Eng. land, is, as we have already shown, if not the equivalent of the cliff lime. stone of Wiskonsin, a rock very closely resembling it. The inference is, that some of the strata of the cliff limestone of Wiskonsin may be expected to furnish building materials of a quality the most superior.

The canal engineers on Rock river complained much that they could find no durable building stone, having quarried in the white limestone which occurs at the margin of the great coal-field. This rock (at that point at least) is little suitable for building purposes. Had these gentlemen ascended the Mississippi to the high land above the Mekoqueta for material, they would have found quarries of the building stone above described, and their locks might have bid defiance to the ravages of time.*

Near Iowa City, and in several other localities along the junction of the cliff limestone and the coal-measures, occurs a white limestone, which must not be confounded with the above. It is capable of receiving a good polish ; and, being studded with a beautiful fossil coralline, (the styling of Lesueur) forms a pretty, variegated marble. (See sketch No. 11.) One of my sub-agents found a settler building his milk-house of this showy material, in which the cyathophyllum of Goldfuss was intermixed with the stylina. Its value as a marble may be considerable, should it be obtained in blocks of sufficient size. In polishing, however, the organic structure of the coralline causes cellular imperfections on its surface.


In section twenty-two, township eighty-nine, range three west of the fifth principal meridian, the United States surveyors had reported a “millstone quarry." There seems, however, to have been no better foundation for this report than the presence of some granite boulders, very numerous on the northern portion of the eastern boundary of the district, and also throughout the western ranges of Iowa. These erratic boulders constitute a peculiar feature in the prairie scenery, and are often of great size. One was reported to me by a sub agent, somewhat indefinitely, as being "as large as a steamboat.” A smaller one, afterwards measured, was eight feet high, and ninety feet in circumference. They are composed of granite, green stone, porphyry, and other primitive rocks.f

* Even within a much shorter distance, to wit, at the mouth of Quarry creek, where the cliff limestone first makes its appearance in bluffs on the Mississippi river, (on the southwest quarter of section 26, township 29 north, range 5 east of the fifth principal meridian,) they might have found very good building material. This rock, in its external appearance, much resembles freestone, and was reporied to me as such by my sub-agents. If it was seen by the Mlinois engineers, they may possibly have rejected it from a similar error. Analysis, borever, proves it to be a irue magnesian limestone.

+ 1'hey are much more frequent towards the heads of the streams than they are near the Mississippi river. In.crossing The line between ranges seven and eight of the fourth principal meridian, they commence very abruptly, and are found in great numbers, and sometimes of very large dimensions,

Similar boulders, in the State of Illinois, are, in default of more suitable materials, sometimes employed to make millstones; but the labor of the manufacture from these primitive rocks is very great, and a “millstone quarry” of such a character cannot be considered of value.

In the course of a geological reconnoissance of the State of Indiana, (which, as geologist of that Stale, I had, two years since, occasion to make,) I found good millstone quarries in a rock formation which is the equivalent of that of Wiskonsin: and I had hoped to make similar discoveries in the course of this survey; but I have seen no rock, either in Iowa or Wiskonsin, which combines hardness and porosity enough to render it suitable for this useful purpose.


No minerals of much value, except those described in the preceding sections, were detected in the district.

Chalcedony, agate, jasper, and cornelian were found, but not in great perfection.

On the southwest quarter of section seventeen, township eighty-four, range five east of the fifth principal meridian, in the Mineral Point and Blue river lead-mines, besides several other localities, was found a white rock, which, by disintegration, forms a white plastic material used in the manufacture of porcelain : it is a hydrate of silica, containing a small percentage of alumina, and is similar to that substance which forms what are misnamed the “ chalk banks," below Cape Girardeau, Missouri. If obtained in sufficient quantities, it would be of value in the manufacture of porcelain; but I failed to discover any extensive or continuous stratum of this mineral. It has too large a percentage of silex, and too little alumina, to rank as a true kaolin.

No appreciable quantity of silver was discovered in any of the ores of lead subjected to analysis ; neither was any sulphuret of silver (as it occurs in the lead-mines of the Hartz) found in this district.*

In one or two specimens of galena, vestiges of arsenic were detected.

Little or no antimony is found in combination with the lead ore of this district; a circumstance which increases the value of the ore, for lead ore contaminated with antimony is of difficult reduction.

At McKnight's diggings, at Mineral Point, there occurs along with the galena the "black-lead ore” of the mineralogist, which is the carbonate of lead with a small admixture of sulphuret of lead.

Crystals of the sulphato tri carbonate of lead have been obtained from some of the diggings in Wiskonsin.

Manganese, a metallic oxide, useful in various manufactures, was found (but not in a pure form, nor in very large quantities) among the earthy materials in the fissures of the cliff limestone,

In some of the richest lead-inines, very fine specimens of crystallized iron pyrites are associated with the sulphuret of lead-some of it (capillary pyrites) brilliant and delicate beyond any I had ever before seen. It is composed of fasces or clusters of silk-like threads, of a pale golden-yellow color, which may be readily separated with the point of a knife.

* Ores of silver are rarely, if ever, found in this geological formation.


An item in my instructions required me to report " such facts as we serve to convey some idea of the value and productiveness” of the dista: under consideration.

In obedience to this instruction, I have analyzed, with care, the soils of Iowa and Wiskonsin ; and the result of this analysis, extended to fifteen different specimens selected from the various parts of the district, is truly remarkable.

It is a common, and usually a correct remark, that mineral regions are barren and unproductive. “If a stranger," as Buckland has well er. pressed it in the opening to his Bridgewater Treatise, “ if a stranger, landing at the extremity of England, were to traverse the whole of Corawall and the north of Devonshire, and, crossing to St. David's, should make the tour of all North Wales, and passing thence through Cumberland, by the Isle of Man, to the southwestern shore of Scotland, should proceed, either by the hilly region of the border counties, or along the Grampians, to the German ocean, he would conclude, from such a journey of many hundred miles, that Britain was a thinly-peopled, ste 71 region, whose principal inhabitants were miners and mountaineers."

Not so the traveller through the mining districts of western Ameriia. These afford promise of liberal reward, no less to the husbandman than to the miner; and a chemical examination of the soils gives assurance that the promise will be amply fulfilled.

The mode of analysis adopted was, in its general features, the same which has been recommended by Dr. Dana, of Lowell, and adopted 15 the geologist of Massachusetts. I have carried it out, however, in reni to the salts found in the most interesting specimens, into more minute detail than that simple and practical, rather than rigidly accurate, mode of analysis presupposes.

The following table, with the appended notes, exhibits, with sufficient accuracy for practical purposes, the proportions of organic and of earthy matter, the percentage of saline ingredients, and the specific gravity of each specimen of soil. The specimens were selected from the different formations-chiefly, of course, from the cliff limestone; they were taken from about six inches below the surface, and, with a single exception, (No. 13,) from wild lands. They may be considered a fair average of the virgin soils of the district.

« AnteriorContinuar »