yellow clay; also some boulders are found of a very hard breccia made up of angular fragments of flint containing fossils cemented by ferruginous clay and sand. Indeed there are perhaps few primitive rocks of much durability that are not found at some place or other in this clay. Quartz, milky, greasy and nearly black, basonite, porphyry, gneis, all the hard varieties of iron ore, geodes, and a certain hard stone, which the country people say can not be broken, and supposed to be saussurite, as that is said to be the most refractory of rocks. The general appearance of this formation is attempted to be shown in the section, every thing there represented having been seen and examined by myself, in wells when being dug, and on the surface. Two places were carefully examined in Danville and vicinity, where the excavators exposed sand resembling beach sand regularly stratified as left by the waves: many other places have been mentioned to me, in all of which the sand rendered the cistern useless by drawing off the water. It is on this clay, the vast prairies of our country mostly lie, not that timber will not grow on it, though no kind grows so thriftily as on the soil resulting from the disintegration of the limestone in the hills,but because it is on this that grass obtains its maximum luxuriance, the annual burning of which destroys and keeps down the growth of timber. The maximum thickness of this formation has not been ascertained. One hundred feet has been passed in the vain attempt to get water in some large prairies without getting through it. In small prairies it is generally about twenty feet thick. It can readily be conceived, why it should be thinner in these than in large prairies, when it is recollected that the entire formation has been removed by the action of rain and running water, except on the highest lands; hence broad flat prairies have suffered less from this cause, than small ones which are always more rolling. It is almost universally found, that where the clay has been most removed,the accompanying rocks lie the thickest, as the water removes the clay and leaves the more durable rocks. In some very large prairies a rock is seldom seen, yet by looking about, an observer can occasionally find a boulder protruding above the clay. Chert, or silicious stones, commonly abound throughout this formation that are more or less charged with organic remains, some of the lumps being almost wholly made up of encrinites and shells. Encrinites, pentacrinites, very large and very small spirifers, penbrenites, pentamen, producta, orthis, teretratula, and numerous other shells, some of them exceedingly small, others large. It should be remarked, however, that in nearly every case the shell has entirely disappeared, leaving only the internal and external form or cast. In a few cases, the shells of spirifers, with the internal spiral arrangement, has been beautifully preserved in pellucid quartz. It should be observed in this connection, that this clay is interspersed throughout with rolled pebbles precisely such as are found upon the seashore, varying in size from a dozen pounds weight to that of sand, and of every shade of color, from the most transparent quartz to red, green, blue and black pebbles, all very hard and smooth as though they had been frozen to the bottom or lower portion of ice near the shore; and carried away with it when warm weather broke up the freezing and suffered the ice with the pebbles attached to move away. Under these circumstances, one would expect the ice would have attached itself also to recent shells at the bottom of shallow water near coasts: this may have happened: but those shells could not well have become fossilized in the boulder clay, but would not, and the clay could not retain even their form or impression. It has been said by some, that shells not fossilized have been found in or on this clay; but I think that they were muscle shells, that had been collected in rivers and carried to the highlands, to be used as food by the aborigines of the country. The boulder clay appears to have been deposited upon the bottom of a shallow sea, and to have been conveyed hither by floating ice. The evidence of the first is to be found in the fact that this deposit rests sometimes on the fine grained sandstone, sometimes on the encrinital limestone,and occasionally on the coralline bed; the rocks above having been removed by the action of waves and currents in shallow water, so that the clay rests unconformably on them. The second seems to be proven by the impossibility of conveying gigantic boulders four or five hundred miles, and strewing them over a sea bottom by any other agency known than ice floes. It would seem that icebergs, loosened from certain cliffs, where they became charged with clay and rocks of definite kind, were afterwards stranded in particular places by coming in contact with bottom; because the hard rocks, in certain localities, are frequently of the same kind, and immediately adjoining, perhaps on the next acre, they are of a different kind. One locality may be seen strewed thickly with rocks of volcanic origin, as basalt and greenstone, many of which are in large balls, made up of concentric layers like the coats of an onion, another strewn as thickly granite boulders without mica. And still another with chert, highly charged with organic remains, of a date later than those contained in rocks below, and all these, sometimes repeated, may now and then be seen on a few hundred adjoining acres. This clay is frequently passed through in digging wells, (though in some places in large prairies, one hundred feet has not reached the rook below), when sometimes the fine grained sandstone, sometimes the new encrinital limestone, and in one place, in Nine-mile-prairie, the coralline, hard, smooth, water-worn, and full of corals, was found at the bottom of a well underlaying the clay. The surface appearance is generally as above mentioned, different localities showing different kinds of rock in the soil; but by penetrating the clay vertically, we find the various kinds at different depths, thus showing that the deposit was gradual, and that various icebergs were stranded on the same place at different times, and thus the sea bottom was covered to some hundreds of feet with this miscellaneous formation. The general color of the boulder clay is compounded of the shades between white and red, generally yellowish, but very variable in color, seldom dark or black: even the blackest hornblend boulder decomposes into redish clay. We suspect, also, that much of our boulder clay came here in the form of stone, for upon penetrating the clay, we sometimes find portions of it imperfectly stratified, occasionally stratification is perfect very short distances, as in sand, (see the section), but we now for BOULDER CLAY. 1. Boulders, red green, black & mixed. 2. Rotten boulder crushed by pressure. 3. Rotting rose colored granite with unrotted nucleus. 4. Semi-stratified clay of different colors. 5. Finely stratified sand,like beach sand. 6. The general mass of the boulder clay. Fine grained sandstone & conglomerate. NEW ENCRINITAL LIMESTONE. Place of the bituminous coal. CORALLINE LIMESTONE. OLD ENCRINITAL LIMESTONE. Variegated marlite and Jefferson building rock. Prismatic, or coralline sandstone. White sandstone. A succession of marlite, limestone, arenaceous and argillaceous limestone; but no continuous sandstone, reach from the white sandstone to the water line of the Missouri river, a distance of near three hundred feet at Jefferson city. Some fine oolitic limestone, in given in this section. and then encounter a mass of clay not like that which surrounds it, but all alike. On one side of a large cistern, while in being dug, I saw a mass of clay, some ten feet in diameter, much redder and more homogeneous than that surrounding it, with a nucleus of rose colored felspathic granite in the center, about a foot in diameter. That this had been a boulder cf about ten feet each way, was as plainly marked as if the whole rock had remained solid granite. As regards the manner of depositing this clay, it appears to me, that taking the whole of the observable phenomena together, impossi ble to arrive at any other conclusion, than that it was deposited in water. How otherwise can we account for the seams of finely stratified sand that are occasionally met with, sufficiently extensive to carry off water from a cistern well. For it should be remembered, that persons that live on this formation have no springs, nor can they obtain water by digging wells in the ordinary manner; but they form cisterns by digging in the common form for a well, wall it up and running in water from above by means of a house roof or shed constructed for the purpose. In this way the cisterns, or wells as they are here called, hold water perfectly; except when in being dug a seam of stratified sand is encountered, and so well are well diggers aware that this will drain off the water, that, unless the sand is so near the surface, that they do not care for the water to stand higher in the well than where the sand occurs, the digging is at once abandoned and another site sought for at some distance, so as to avoid the sand. The glacial theory might account for the different kind of rock being found near each other in groups, because in countries where much upheaval has taken place, very different rocks are near each other on the same place, but cannot account for the great difference in the kind of rock found at different depths overlying each other in this singular formation. What is meant by the glacial theory here, is the doctrine imputed by an American writer, whose notice I saw in some periodical, to Mr. Lyell and M. Agazis, to wit, that the scratches found on rocks, and the dispersion of boulders was due to the action of ice upon land; true glaziers; and that to support it, they had manufactured an ultra arctic climate for our hemisphere at a late period of its history. It is but justice to these very eminent gentlemen, to say that I have seen nothing of the kind from themselves, except Lyell's Hypothetical Climates in his principles. The strongest argument to my mind, in favor of the glacial theory, is the scratches observed on mountain or hill sides, apparently made upwards. Whether these are entitled to the weight assigned to them, I can not say, having not seen anything of the kind, but have thought that by possibility the country may have been elevated since the scratches were made. We can all see how rock may be scratched at the bottom of a shallow sea by icebergs, such as we now see in the northern seas charged with rock that portion of the floe heaviest charged with rock, of course, would hang below, and when considerable momentum should be given the iceberg by wind or oceanic currents, upon coming in contact with the bottom, would plough it up if soft; and if hard rock, as limestone, and the iceberg contained at its bottom a hard quartz or granite firmly held in the ice, as the glacier's diamond in metal, the limestone would be scratched more or less in the direction of the wind or current, as has been observed in Ohio and elsewhere. Further, I can not conceive how it would be possible for glaciers to remove much the largest portion of the fine grained sandstone, and a great deal of the new encrinital limestone, and carry the debris hundreds of miles (for it has not been left in this basin) and deposit the drift upon the sloping and denuded edges of the rocks. But the sea may have done it. And the natural effect of water in a shallow sea would be to denude such portions of its bottom as was most elevated, and carry the debris away. The country attempted to be described in this paper, constitutes a small part of an extensive basin, extending from an anticlinal axis in Indiana on the East to a supposed axis of elevation crossing the Missouri river near Jefferson city on the West: and from the Ozark mountains on the South, to where the coal bearing rocks crop out, not very far from latitude forty-two on the North. Intermediately the rocks are nearly horizontal, not dipping from the anticlinal axis near Jefferson city to the Mississippi river, more than about three hundred feet in a hundred miles, and showing scarcely a fault or a fracture, so that they have never been more disturbed in position than they now are. FINE GRAINED SANDSTONE.-The upper member of hard rock visible in our region, is the fine grained sandstone, which is only found occasionally lying upon, or filling depressions in the next lower, the new encrinital limestone. It is a fine grained sand rock, variegated, reddish, bluish and ashy white sometimes minutely stratified, the strata occasionally differently colored. It is what is called sharp grit, that is the particles appear to be angular or very little rounded; hence it affords good grindstones. It is not micaceous at any point seen by me. The very minute sparkling particles sometimes seen on its surface, seem to be reflections from facets of quartz particles. I do not know what its capacity may be for resisting high degrees of heat, but it looks like some fine sandstone I have seen. No organic remains have been seen in it, though it must be confessed that very little search has been made for them. It seems in one place to be capped by a light conglomerate consisting of rounded pebbles in a clay matrix, and light iron ore in small cubes. Again its place appears to be taken by brown oxide of iron in stratified masses like the sandstone, which is sometimes so arenaceous as to constitute a true ferruginous sandstone: but is frequently a pure brown oxide of iron. This rock is admirable adapted to building purposes, being soft in the quarry, so as to be cut freely with the pick-axe, but becoming hard by exposure to the air, maintaining sharp angles when it is exposed in cliffs without much cracking. The diversity of color seems to depend upon the presence of iron in different degrees of oxidation. It sometimes becomes blacker upon exposure to the weather, and I think always redder by much heat. This is obviated in selecting for architectural purposes by choosing the ashy colored portions of the rock, which, indeed, predominates. As before observed, this rock is only found in detached masses, filling depressions left in the rock below by movements of elevation |