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Chapter 7

This webpage reproduces a chapter of
Iowa As It Is in 1856

N. Howe Parker

Chicago and Philadelphia, 1856

The text is in the public domain.

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Chapter 9

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p37 Chapter VIII

Geology of Iowa

In preparing the following, we depend principally upon "Owen's Geological Report" of a survey made under his direction, of the Northwest Territory, by authority of Congress.


The principal minerals of Iowa are lead, iron, and copper. The shipment of lead from Dubuque, from the 21st of March to the 1st of December, 1854, inclusive, amounted to 43,543 pigs, weighing 3,069,640 lbs.; valued, at the mines, $178, 830,20. Lead has been found at various other places near the base of a bluff on the west side of the Mississippi, some ten or fifteen miles above Turkey River, near the French village. From seven to ten thousand pounds of lead ore were taken from openings in the rocks by Dr. Andrus. More or less "Galena" is found here in all the principal openings for the distance of a mile. Between the Yellow and Upper Iowa Rivers, excavations p38are visible where the Indians have dug for lead ore. On the Upper Iowa, also, ore has been discovered in several places in considerable quantities. In the Winnebago Reserve, not far from the Iowa River, and a few miles northwest of the town of Lansing, lead ore has been found in small quantities, chiefly in pockets and cavities.

Copper ore has been discovered within the boundaries of the State, but not sufficiently productive to justify the sinking of shafts. Iron ore is found in various places in the Des Moines Valley; Owen thought, in some locations, of sufficient productiveness to justify smelting. There are, as yet, no works for working raw iron ore in the State.

Coal-fields of Iowa

Last summer, the following article appeared in the Des Moines Valley Whig. Having compared it with other authority, we find it quite correct, and insert it entire, with additional data, gathered elsewhere, as a condensed view of Iowa coal measures, &c.:

"The Des Moines River runs centrally and diagonally through what is geologically called the Carboniferous System of Iowa. This system is called carboniferous, because it is that particular division of rocks in which the 'coal measures' are found, and because it contains that series of rocks, of a comparatively modern date, which, in their composition, are so largely carbon.

"The physical and pastoral features of the Des Moines Valley are thus given in Owen's Geological Survey:

" 'The carboniferous rocks of Iowa occupy a region of p39country which, taken as a whole, is one of the most fertile in the United States. No country can present to the farmer greater facilities for subduing, in a short, wild land.

" 'For centuries the succession of natural crops of grass, untouched by the scythe, and but very partially kept down by the pasturage of buffalo and other herbivorous animals, have accumulated organic matter on the surface-soil to such an extent that a large succession, even of exhausting crops, will not materially impoverish the land.

" 'The rural beauty of this portion of Iowa can hardly be surpassed. Undulating prairies, interspersed with open groves of timber, and watered by pebbly or rocky-bedded streams, pure and transparent; hills of moderate height and gentle slope; here and there, especially towards the heads of the streams, small lakes, as clear as the rivers, some skirted with timber, some with banks formed by the greensward of the open prairie; these are the ordinary features of the pastoral landscape.' (Report, p100.)


"The Iowa Coal-field embraces an area of about 25,000 square miles. A very good idea of its locality may be obtained by taking a map and drawing a line, commencing near the southwest corner of the State, proceeding up the Nishnabotna; thence to Lake Boyer; thence, by the heads p40of the Three Rivers, northeast, to the Des Moines, crossing it six miles above Fort Dodge; thence southeast, through Tama and Iowa Counties, to the east part of Washington County; thence nearly south, through the west part of Henry and Lee Counties, to the Des Moines River, near St. Francisville. It is nearly in the shape of a half ellipse, cut by the shortest diameter. The width of it east and west is nearly 200 miles; while in a north and south direction, the distance is 140 miles. The Des Moines River traverses, in a southeast direction, about 250 miles.

"The accompanying table has, with much care and some labor, been compiled from Owen's Report, for the purpose of giving a view of the thickness of the coal veins as they show themselves in the Valley proper, and in the banks of creeks near by:

" 'Tabular View of the Coal Beds in the Des Moines Valley

Counties Range Section Veins General Remarks
N W Ft. In.
Lee 66 9 23 1 Quality poor.
Clark, Mo. 67 8 36 3 Quality good.
Van Buren 68 8 24 4 6 Night's Bank, good.
68 8 34 4 Regular 4 to 5 feet.
68 8 25‑26 2 Slaughter's Bank.
69 8 & 9 32 2 On Bear Creek.
69 9 25 1 6 Gillis's Bank.
70 11 3 4 Near Portland.
Davis 70 12 22 2 2 seams, 2 feet each.
Wapello 72 13 3 5 feet higher, 18 in.
73 15 20 Not given.
Mahaska 74 15 19‑30 4 Quality tolerable.
74 17 6 3
74 17 32 2 6
p41 Marion 74 18 2 2 Right bank Cedar.
74 18 12 3
74 18 16 5
74 18 30 Regular 4 to 6 feet.
74 18 14 2 2½ feet poor.
75 20 3 3 White br'st ex.
76 19 14‑23 4 "
76 19 11 Not given.
Polk 78 23 23 "
78 24 4 2 Regular 2 to 3 feet.
Boone 81 25 2 to 3 feet inferior.
83 26 5 Not given.
Note. — Last bed mentioned in latitude 42°30′ north.'

"The foregoing table does not include the thinnest veins, nor half the localities where the thick ones crop out; but one can get a very correct view of the thickness of the best seams up along the Valley. There are undoubtedly outcrops where the thickness is much greater than in any of the places mentioned. But these will be found to be the centre or side of a basin which, on being worked, will not extend far. A basin of 15 feet of thickness has been found in a bank opposite Farmington. Where the outcrops are more than four or five feet, they must be suspected as being basins, unless in the cut of a stream at some distance the vein is ascertained to have the same thickness. Owen says there is no vein of more than from four to five feet in Iowa. (Report, p20.)

"The table shows outcrops are far more numerous in some localities than in others. In the immediate vicinity of the river, where the limestones, which lie below the coal, make their appearance, the coal strata are usually p42wanting. This is the case at Bonaparte, Bentonsport, Keosauqua and Ottumwa. But in these the coal strata may be, and actual are, found in creeks at no great distance from the river; sometimes, even upon the bluffs.

"The southeast and northwest parts of Van Buren County, the northeast part of Davis, the central part of Wapello, the southern part of Mahaska, and the southeastern and central parts of Marion, are rich in coal. But other portions of the same counties are not wanting. So far as can be learned from the table, and so far as the observation and knowledge of the writer extends, the heaviest beds are usually on the west side of the river. The best beds are also there. Some of these are also on the White Breast, Cedar, and Soap Creeks. The principal exception to this rule is in the southeast part of Van Buren County. Here it exists in great abundance on both sides of the river. It is equal in quality to any found below Marion County. Two veins are worked to considerable extent in connection; the two afford from 4½ to 5½ feet. On the west side of the river, it is said the two are separated by a vein of fire-clay, which thins out, and the coal veins converge as they recede from the river. These veins are shown in the cuts made by the creeks for miles in distance to the west. During the year ending with the current June, more than 100,000 bushels have been taken from three banks near Farmington, two of which are east of the river. Some of this has been conveyed by blacksmiths the distance of 75 miles into the State of Missouri. The greater part of it has been transported to different places by wagons.

p43 "The average value of it at the bank is 6¼ cents per bushel. The value at the Mississippi, a distance of 30 miles, is 18 to 20 cents a bushel. Whenever the banks shall be well opened, and there are ready and convenient means of carriage, so that colliers can find regular employment, coal can be delivered on the banks of the Mississippi at a cost of 6 or 7 cents a bushel, and afford a better profit than at present. This is upon the supposition that it can be conveyed upon a railroad car here as cheap as in Kentucky, where the cost of the operation is one cent per bushel per 100 miles. And as to the amount of coal the Valley can supply, it is easy to ascertain it. Allowing a bushel to the cubic foot, one acre, with a two-feet vein, will give 87,120 bushels. With a four-feet vein, one acre will give 174,240 bushels. One hundred acres, with a four-feet vein, will yield 17,424,000 bushels. One square mile, with a four-feet vein, will yield 113,513,600 bushels. The transportation of this 100 miles, at one cent per bushel, would yield the snug purse of $1,115,136. And as the demand for coal would at once be increased to millions of bushels a year, if a railroad was constructed in the Valley, this mineral alone would afford quite an item of business and profit.

[image ALT: A schematic drawing of several heaps of rock; without the caption, given on the webpage, it would be completely opaque.]

Section on Creek near Rockingham, Scott County,
showing out-crop of Coal.

L, Devonian limestone, 18 ft. C, C, Coal, 9 ft. above creek.
T, Talus. S, Shale. L, Devonian limestone, 11 ft.

"Hydraulic Limestone

"Of this kind of stone is formed a mortar which will set under water. It is essential for all masonry exposed to the water and to dampness. There are several varieties of it: one is called Septaria. This is found in the form of round or flattened balls, of various sizes. This is the kind p44from which the English prepare the celebrated Roman cement. (Hitchcock's Geology, p20.) Comstock speaks of it also as 'Argillo-Ferruginous Limestone.' This, however, is another variety of cement-rock, and is, perhaps, the most common. It is called black calcareous rock, cement rock, and hydraulic limestone. In reference to the geological formations in the Valley, Owen says, 'The middle division of the Iowa Coal-field affords, at many localities, iron-stones of various qualities, associated frequently with hydraulic calcareous cement, which occurs either in the form of disconnected septaria, or regular beds.' (Report, p21.)

"Cement rock is found both above and below the coal, but in the largest quantities above. The reader will find mention of it by consulting Owen's Report, pp112, 127; and more frequently still in that part of it which gives the geological structure between Fort Des Moines and Fort Dodge. It is a very common rock in the Valley; probably in every county on the River below Fort Dodge. In many places contiguous to the river in Davis County, there are strata of it several feet in thickness. The geological structure of the southeast and central parts of Marion County are just the same as in Davis. But as the series of rocks above the coal show, themselves more extensively above Racoon Fork, we accordingly find more frequent mention of it in that region. In some places large quantities of it are wrought into cement, which is quite extensively used in the river improvement. The initials of it by analysis are:

"Carbonate of lime 63.6
Silica 15.5
Alumina 8.3
Protoxide of iron 7.4
Magnesia 1.2
With a small portion of manganese, soda, and potash.

"It will be readily seen that the demand for this is great, when it is said that $6000 worth, at the ordinary prices, will be wanted for every lock on the river, and when it is also said that in nearly every dwelling in the western country, aº cistern coated with this cement will be indispensable as the means of obtaining a supply of pure, soft water. The walls and floors of damp cellars must also be laid in cement. And the cement of this Valley will be wanted because it is more accessible; the present demand being supplied, in a great measure, from La Salle, Illinois, and from Louisville, Kentucky; and also because the Valley cement is probably fully equal to that from other places. That the reader may see how its constituents compare with other cement, we will give the analysis of that which is extensively used in the State of New York. Its composition, according to Professor Beck, is:

"Carbonate of lime 50.70
Silica 15.37
Alumina 9.13
Peroxide of iron 2.25
Magnesia 12.35

"Comparing this analysis with that of the Valley cement, it will be seen that they are substantially the same. We p46will here add a practical remark, which may be of much value to those who undertake to manufacture this cement, and to those who undertake to test specimens. Very much depends upon burning it. If care be not taken, the best element may be easily spoiled. In St. John's Geology, p274, will be found the following:

" 'Greater caution is requisite in burning hydraulic lime, since it is fusible, and the heat applied to the common lime will vitrify this substance and render the process quite imperfect. Common lime will bear a white heat; but the calcination of hydraulic lime is not well effected above a red heat.'

"When proper arrangements shall be made for working this limestone, it is said the cement can be afforded at the kiln for $1.25 a barrel. The carriage of it to the Mississippi by land is at most $1.00 per barrel per 100 miles; while cement from other places costs from $3.00 to $3.50 per barrel.

"Common Limestone.

"Though this is regarded as prevailing rock in the West, there are large sections in Iowa where the limestone is so largely magnesian as to be unfit for quick-lime and mortar. The proper position of the common or mountain limestone in the carboniferous system is below the coal. Accordingly, it is found all along the Valley in the greatest abundance and of the best quality. Much of it contains 90 per cent of carbonate of lime. This is among the most valuable of stones for quick-lime.

[image ALT: An engraving of a landscape with a series of tall more or less cylindrical bluffs along one bank of a small and placid stream. It is a formation of magnesian limestone in Iowa.]

Castellated Appearance of Lower Magnesian Limestone,
Upper Iowa.

"Closely allied to this stone, and still lower in the system, p47is the blue lime-stone. Some of this is deep blue, and some, of a bluish gray. It is harder and common limestone, often highly crystalline, and fossiliferous. It usually lies in strata in the Valley, varying from a few inches to some feet in thickness. The stone is good for quick-lime, but is of superior quality for building material. It is as beautiful and durable as Quincy granite, while the cost of putting it into the wall is comparatively trifling. The principal places where it is accessible are Keokuk, in the bed of the river below Farmington, Keosauqua, and Ottumwa. It will undoubtedly become an article of export as soon as it shall become known, when a demand for the best building material arises, and the proper means of transportation are provided.


"The writer claims that there is marble in the Des Moines Valley, of a good quality and in great quantity. 'Any limestone which is sufficiently hard to take a fine polish is called marble. Many of these are fossiliferous.' (Lyell's Elements of Geology, p12.) In the limestones beneath the coal there are several varieties which come under this definition. Among them may be classed some of those named under the previous head. The best quarry now known in the Valley is at Keokuk. Some of the strata there are highly crystalline — almost saccharine — and take a fine polish. St. Louis has already resorted to this place for building material; a fact which shows that this marble is superior to any other equally active to that p48city. At the same locality are other varieties which polish well. They are crystalline, solid, but full of fossils, and either blue, or of a bluish-gray color. Of the latter varieties, enough can be had at Bonaparte, Bentonsport, and Keosauqua. And very probably, when these quarries shall be extensively worked, the white marble will be found.

"Not far from Keosauqua there is a good variety of light-gray, compact, granular marble, of which tomb-stones are wrought by Deacon M. B. Root. It effervesces slightly with acids, and takes a polish. Iowa sent a block from this quarry to the Washington Monument. Ottumwa may expect to find as good varieties of marble as any place, because the lower limestones have the greatest uplift there.


"On Reed's Creek, some distance from its mouth, not far from the line between the counties of Lee and Van Buren, are heavy beds of quartzite. The color of it is nearly white — sometimes, a light blue; and it is so slightly adhesive that it can easily be shaved off with a spade. Plasterers, when working in the neighborhood, are accustomed to obtain it for their 'finishing-coat.' Those of them who have used this, and also that obtained at the Falls of St. Anthony, say that the two kinds are just alike. Examined with a magnifier, the sandstone on Reed's Creek is sharply angular, and appears to be very pure quartz. The slight coloring it has received has probably been obtained from the superincumbent earth. For plastering purposes, it cements as well with lime as that of the Falls; and if it p49really be like it, these beds are a source whence can be obtained the best materials for the manufacture of crystal glass.


"Passing by the kinds from which common brick are made, and those used for earthen and stone-ware, the coal measures abound in 'fire-clay.' Fire-proof bricks are wrought of this for the use of foundries, furnaces, and in all cases and places where there is an exposure to intense heat. In the Eastern States, it has sometimes been necessary to import these bricks from England. The cost of them has been as high as $50 per thousand. It is desirable that fireplaces and ovens should be constructed of them; and where fire-clay is plenty, as in the Valley, there is no reason why they should not be. But bricks are heavy articles of transport; and until there are railroad facilities of carriage, that one item of cost will prevent extensive business in this kind of manufacture. With such facilities, there appears no good reason why this clay should not be worked. And as to quantity, the Valley can supply the United States, with Cuba and Mexico annexed!

"Iron Ore

"Iron has been found in several places, though no beds are known in the Valley of so rich a character as those of the 'Iron Mountain,' in Missouri. Owen found this ore in Marion County, in beds which he considered would hereafter be worked. Specimens taken from them and examined had a specific gravity of 3.45; that of pure iron being p507.7. By analysis, they contained 35 per cent of iron. This iron, as to richness and quality, is almost exactly like the 'Cairnhill Black Band,' of Scotland, which is extensively worked. Other and heavier beds have been discovered since Owen's Survey; but whether rich or not, is not certainly known; the ore not having been tested by competent men. In such circumstances, it is not possible to speak of this ore with great definiteness.

"Gypsum, or Plaster of Paris

"This is chemically known as the sulphate of lime. The heaviest beds of it in the United States are to be found a few miles below Lizard Fork, in Yell County. They are from 20 to 30 feet thick, and show themselves on both sides of the river for miles; and they extend back each way an unknown distance. By analysis, this gypsum contains 70.8 per cent of sulphate of lime.

"On one acre, with an average thickness of 20 feet, there will be 871,200 cubic feet; on one square mile, 557,568,000 cubic feet; and on three miles square, 5,018,112,000 cubic feet and 308,031,428 tons.

"Before closing this paper on the minerals of the Valley, it is proper to say that the survey of Dr. Owen was made by order of the United States, and had for its more special object the discovery of mineral lands, such as the Government might wish to reserve. The principal minerals sought were land and copper. The coal-field was surveyed and mapped down, while the other minerals noticed in this paper received only incidental attention and secondary consideration — some of them, no mention at all. Could there p51be a thorough geological survey by the authority of our own State, it is probable that valuable discoveries would be made in the Des Moines Valley, as well as in other part of the State.1 The multitude of streams which debouch into the Des Moines have not been explored to any considerable extent.

"Collectively, the minerals of this Valley, as now known, are extensive and valuable. They constitute one of the many items which render their locality so attractive. It is traversed by one of the most beautiful rivers on earth; 400 miles in length, a large portion of it 250 yards in breadth: capable of floating steamers a part of the year, and affording water-power to any desirable extent: with a landscape of great and charming variety, groves, and forests, and prairies, in constant alternation, and possessing a soil 'scarcely excelled for fertility, perhaps, in the world,' why should it not be thronged with inhabitants? It is the centre of the 'Mesopotamia of the West,' in a more important sense than that of its position. Let but the iron horse traverse the whole length of the Valley, and its silver stream will be skirted with cities and villages in as great continuity as is the Bosphorus; meanwhile, its agricultural, and mineral, and manufactured exports, will amount to many millions of dollars annually."

The Author's Note:

1 By reference to the chapters on particular counties, in this work, it will be seen that discoveries of iron, copper, lead, and coal have been made in localities not specified in the foregoing paper. At its last session, the Legislature passed an act appropriating $2,500 per year, until the work is completed, for a thorough geological survey of the State; the work to be performed by a geologist and a chemist, to be appointed by the Governor.

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