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1 cupy a place above the coal. That it is super-carboniferous, we have no
evidence whatever in the Territories. On the contrary, though the strata emerge in succession from beneath this formation, and present themselves
to the eye of the geologist to the depth of from six hundred to one thousand · feet as he ascends the river, still not a vestige of coal appears associated with these inferior beds.
From a careful personal examination of the rocks at numerous localities s of both regions, viz: in Ohio, Indiana, and Kentucky, on the one part, and
in Iowa, Wiskonsin, and Illinois, on the other, I am satisfied of the followwing agreement or correspondences :
1. The rocks, both in Ohio and in the lead region of the Upper Mississippi, are horizontally stratified in distinct layers, separated generally by simple joints—the layers being of various thicknesses, from a few inches to eighty or one hundred feet; they are traversed vertically by fissures which are often several feet wide, and filled with red clay* or lead : with red clay in Ohio, but with red clay and lead in Iowa and Wiskonsin. . 2. In consequence of being thus fissured, the rocks in both localities, when partially removed by streams, or otherwise, form mural or overhanging cliffs ; hence it has been denominated the “cliff limestone."
3. They agree in external characters; being, for the most part, a tolerably pure magnesian limestone, which effervesces but imperfectly with acids, until reduced to powder.
The above requires many qualifications, as the characters are much varied in different localities; but even in these qualifications there is an agreement in the rocks of the two regions. The texture is more or less crysta!line; often compact and firm, so as to form a good building stone, or even to receive a polish as a marble—as at Eaton, Dayton, and Columbus, in Ohio, and at Sinsinewa Mound, in Wiskonsin. In some places it is so tender and friable, that it can be broken down by the fingers—as at the north line of Butler county, in Ohio, and at the Natural-rock wells on the Wapsipinecon river, in Iowa. It is sometimes disintegrated to the consistence of sand or gravel-as at Locust grove, in Adams county, Ohio, and at numerous locali. ties in the lead region. It is often cellular, like the internal spongy structure of large bones; a character which has given to it in the vicinity of Columbus, Ohio, the popular name of horsebone limestone. The prevail. ing color is a light drab, or yellowish white; but it is often of a reddish or ferruginous brown: this last color prevails on the Miami, eight or ten miles above Dayton, in Ohio, and is common in the neighborhood of Dubuque, in lowa. At the Menominee river, a small stream between Dubuque and Sin. sinewa Mound, a thick compact stratum, suitable for building, presents itself in a perpendicular cliff, which is of a chocolate brown. I believe the same layer extends to Dubuque, retaining there the same color. In a few situations, the yellowish and red tinge is wanting, and the color becomes an ash-gray, or a simple mixture of black and white.
4. The rock abounds in both localities with chert, (flinty nodules,) which lie horizontally flattened and semistratified, presenting lines or ranges in the vertical cliffs; these flinty nodules are fractured into angular fragments as they lie in their place, and similar fragments are also often found abundantly in the beds of streains; they are of various colors--transparent, opaque, white, reddish and carnelian-like, yellowish, and sometimes banded E agate ; the chert is more abundant in the lead region than in Ohio.
* Red clay fills the fissures of the cliff limestone at Columbus, and at numerous localities in Adams county, Ohio. , , ... . . s
5. The rocks agree in their modes of weathering, by which they oftesa quire an indescribably rugged and fantastic ouiline ; being not only forte into points, angles, and cavities, but often perforated and riddled by Feriecular holes of various sizes.
6. In many places, the stone seems to consist of two kinds of mater. 2. fering in color, hardness, and durability, and imperfectly mixed and borded together, as if one had been formed into a spongy or scorious mass, and the other cast into it to make it solid ; when sufficiently compact for po'isrin this kind of the rock forms an agreeable mottled marble, as at Covotos in Ohio. Perhaps this structure gives rise to the peculiar mode of razeng above described.
7. The rock in both regions is metalliferous, containing lead, inco. ZRC, and manganese; lead is rare in Ohio, but the other metals are not uncos. mon. The Brush-creek iron ore, in Adams connty, Ohio, is in this rock.
8. The rock contains considerable quantities of calcareous spar, or crys. tallized carbonate of lime, disseminated in masses of several inches, or even feet. The spar is abundant in Adams county, Ohio; where it is often res. dered opaque by a black substance pervading it, when it assumes the appearance of “galena ;" the same blackened spar occurs in the mines of Dubuque. Sulphate of barytes (heavy spar) is found, rather locally, bor. ever, in both localities; and sometimes small quantities of sulphate of lime, probably formed by the decomposition of nodules of iron pyrites.
9. The cliffs in Ohio, and those in Iowa, seem to produce by disintegration similar soil and the same vegetation ; they are both surmounted by cedars; they occasionally bear the hemlock, (pinus canadensis:) and the groundhemlock, (taxus canadensis ;) in the precipitous ravines, they have Tufts of the same purple-stemmed fern (pteris atropurpurea) growing from the crevices of the perpendicular rocks, and have the overlying table-lands covered with forests of oaks, or with the grass of the open prairie.
10. The super position, both in Obio and Iowa, seems to be the same; the cliff rock in both having the blue fossilliferous limestone immediately beneath it. The cliff rock in lowa, Wiskonsin, and Illinois, so far as it eaine onder my observation, occupies the surface, and it was therefore not apparent what belongs properly above it. In Ohio, the cliff is succeeded above by the black bituminous slate or shale.
11. It is often bituminous; apparently more so in Ohio than on the Vississippi.
12. The fossil remains found in the lead region agree with those found in Ohio. Some of them are as follows:
I. Multilocular shells.-Ammonites and orthoceratites.
II. Crustaccans.-Several species of calymene, asaphus, and isotelas, more abundant, it appears to me, in Ohio, than on the Mississippi.
III. Crinoideans.-In many localities the button-like joints of the sterns of various species of stone-lilies are abundant. The column imbedded in limestone has often decayed and left a mould or cavity, in which the slen. der axis is still entire, like a slender wire along the axis of a cylindrical cavity. I have seen this at West Union, in Ohio, and in the huge masses of chert of the Blue Mounds.
IV. Molusca.-Spirifers, terebratulæ, and productæ. A cast of several species of a bivalve occurs, singularly alike, at Eaton and Springfield, 13
Ohio, and on the banks of the Makoqueta river in Iowa. The cast of the i interior presents a thick oval figure, with four beaks; two of which are * longer, and separated by a deep fissure, into which enters a sharp septum. ce? This fissure between the longer beaks gives a distant resemblance to a 21 cloven hoof; hence the common name of " petrified pigs' feet.” They are
often so abundant, that they lie in actual contact. The substance of the C shell itself appears to be entirely wanting; and we find only the cast or -mould, both of the exterior and interior ; the shape of the shell being a "I cavity. No fossil appears to be more characteristic of this formation than "I these casts ; perhaps rather from their peculiar condition than from the L.: specific character of the fossil itself.
V. Zoophytes.—Corallines are abundant in both regions; of cyathophylla, several species; of calamopora, (Goldfuss,) several species ; of catenipora, at least three species are nearly equally abundant. The eschara, (of Goldfuss,) which is abundant on the Miami in Ohio, and which I once thought characteristic of this stratum, seems to be limited to particular localities. I did not see it in the lead region.
These were measured, barometrically, in the same manner as were the heights, as described in the succeeding article. I proceed to make a few remarks upon each, separately :
Section No. 1—through Dubuque.
This section commences about the centre of township eighty-nine north, range one east, of the fifth principal meridian, at the point where the banks of Litile Makoqueta river first attain their chief elevation; and is extended through Dubuque to Sinsinewa Mound, about fifteen miles. The heights along the top of this section are marked at the points where they were taken. It appears that Sinsinewa Mound is scarcely higher than the general table on the upper branches of Little Makoqueta ; its apparent elevation is caused by a “degradation" of the region immediately surrounding it.
The limestone at the top of Sinsinewa Mound is in large, well-defined strata, of a light color, uniform texture, harder than the cliff stone is usually found, and in every respect suitable for a building stone. The same seems to be true, at the same elevation, at the opposite end of the section. I have represented this limestone by a different character; but the line of demarcation is not very definite. The lower portion, three hundred feet, apparently filled with veins of lead ore, is the most interesting development of the cliff rock which I have seen. I have sketched in some vertical veins to represent, in general, the lead ore. I hope no one will imagine that I found veins exactly where these are sketched. Our rapid journey through the region explored did not permit us to dig and blast the rocks to uncover veins of galena. This is a special and peculiar business, and gives origin to a special and peculiar title—that of "prospecter."
This section shows the heights of several points, the general position of the strata, and especially the situation of the blue fossilliferous limestone, which, you inform me, probably limits the thick veins of lead ore. I did not find the blue limestone directly in the range of this section; but, from
its situation above low water at Eagle point, and at the lower mills on Lite Makoqueta, only about two miles distant, and the strata nearly horizonta. it must occupy very nearly the place which I have assigned in the secuon. A geologist residing for months, or perhaps years, at Dubuque, might subdivide this section—trace out the “cap-rock," the thin layers of shalegive specimen sections, ground plans, &c., of individual veins, ard a ra. riety of matters relating to such a locality, which would be interest.es and useful. But the period of a few days, and that crowded with a variety of duties, did not permit the accomplishment of more than was done. I have purposely avoided any thing particular on the lead veins, as I knew that you had much better opportunities for getting information on that subject than it was possible for me to have enjoyed.
A geological speculation.-In viewing this section, it appears evident that the south fork of the Little Makoqueta (a stream barely large ecoceb to turn a mill) has, by abrading its channel for countless ages, worn its bei to the depth of four hundred feet in solid limestone. Is it not probable, then, that the rocks once extended nearly in an uninterrupted level fron the heights of Little Maguoketa to the top of Sinsinewa Mound, and tha: the mighty Mississippi has rolled its tide long enough to have for the chasm, the centre of which it is shown to occupy in the section ? Eit not probable that the whole surface of the country in that region is now mars feet-many hundred feet, indeed-lower than when it first became dry land? Rocks have turned to dust, and the dust been washed away; stones hare dissolved, and the solutions have been poured into the sea. The springs of Iowa show that they have levied tribute from the solid rock, and the waters of the Mississippi tell that they are transporting it to ocean depths. The lead ore piled loosely on the top of corroded limestone shows that the matrix of its vein, into which it was originally cast, has abandoned it to fall down like a ruined wall: a few points, covered by harder materials, remained; gathered the sloping tablets of strata about their shoulders ; reared their heads in defiance to a million of storms; and now, in form of conic mountains, point out a few landmarks of earth's olden boundary.
Section No. 2-at Prairie du Chien.
Here, compared with Dubuque, we find almost an entire change of rocks. Lower strata have been gradually rising, until those which ai Dubuque were at the water's edge are nearly at the hill-tops; and the clutf limestone, which at Sherald's Mound is six hundred feet thick, is here a mere outlier, either entirely wanting, or just capping the hills; while layers of new spe. cies of rock, previously unseen, are raising themselves to light, and form the base and main mass of the hills.
The following is a table of the strata, beginning at the top:
I. Soil and cliff limestone I found but one specimen evidently in situ, and containing a fossil rather abundant at Dubuque-a species of coralline resembling the disk of a sunflower.
II. Blue fossilliferous limestone (abounding with its characteristic fossils, and having its usual external characters) alternating with blue clay marl, the layers of stone very thin and apparently
corroded. I believe it to be identical with that at Cincinnati. I found it in a chasm not filled by other rocks, one hundred and fifteen feet thick ; but the stone was nowhere seen to fill that space, or to be more than thirty feet thick
. - III. Buff-colored limestone in distinct well formed layers, including many portions or masses of white calcareous spar, and imbed. ding few or no organic remains - - - -
IV. Soft saccharoid sandstone, consisting of sharp angular, transparent, minute fragments of quartz, scarcely cemented. It sometimes contains calcareous matter enough to effervesce freely with acids. It is often almost perfectly white, though sometimes colored reddish or brown by iron; when it is thus colored, it is often more strongly cemented. Its close resemblance to common moist unrefined sugar (especially the better or whiter kinds of sugar) does not fail to strike every person who examines it. Although the texture is so loose that a specimen can scarcely be broken off without falling to the state of incoherent sand, yet this rock crops out extensively, and seems to stand the weather as well as other strata which are substantial enough for building stones. I suppose, by its great porosity, it scarcely retains water enough to heave it by frost sufficiently to disintegrate it. I did not find precisely the lower termination of this rock, but, from having seen nearly forty feet of it exposed, I have ventured to give that thickness to it in the section
V. A portion not examined, probably similar to the lower magnesian limestone described next - - -
VI. Lower magnesian limestone, resembling the cliff rock, but differing from it, however, in being almost destitute of organic remains. The lower beds of this stratum frequently afford a good building stone. This stratum exhibits, in some places, alternations of thin layers of sandstone, and some layers of limestone perfectly oölitic in structure. It includes many nodules of chert of a chalky whiteness ; it contains, also, veins of so bright a green color as to excite the idea of copper ore, but yielding no evidence of that metal when examined by a proper test. At the point marked “stone quarry,” this rock has been quarried'for building in Prairie du Chien. It appears to dress very well, has an agreeable lightdrab color, and shows every evidence of durability
It will be seen that the stone crops out beyond the soil at three different points upon the hill-side, A, B, and C. These out croppings are continuous, so as to form three continuous parallel lines for miles in length, and serve to divide the hill into zones, called “benches." When seen from the opposite side of the river, they appear exceedingly straight and well defined, and afford a singular feature in the picturesque landscape.
VII. There is, upon the side of the river opposite to Prairie du Chien, a stratum of sandstone thirty feel thick at the water's edge, identical in character with that three hundred feet higher