This change of the chemical nature of these remains is certainly unaccountable; the Polypifers, for instance, are, when in their live state, of a calcareous nature; yet we find them now, in the strata of our limestone, changed into silex; and the same organic remains which I found imbedded in limestone in a silicious state, I found in a more perfect state, not more than two or three feet higher, imbedded in a stratum of indurated clay, which sometimes, in Middle Tennessee, replaces the slaty clay, in the state of carbonate of lime.

Though Nashville stands upon an apparently elevated spot, which renders its situation exceedingly healthy and beautiful, its strata of rocks are nevertheless lower than the other parts of Middle Tennessee; for whenever any other strata make their appearance, the Nashville strata are covered by them. This is the reason why I commenced my excursions from this point, and extended them in every direction.

The lower stratum of limestone, which is visible near Nashville, on the banks of the Cumberland river, and which we have not been able to examine minutely, as no excavations or quarries of any extent have been made in it, is mostly of a bluish gray, approaching to a blackish gray color. Its fracture is fine splintery, passing into uneven and flat conchoidal, here and there intermixed with spathose glistening particles; or it is sometimes of a fine grained crystalline texture, forming a medium between granular and compact limestone. When rubbed together it has a smell approaching to that of the bituminous limestone. It not unfrequently contains nodules of silex, sometimes resembling chert, sometimes hornstone, which are evidently formed by infiltration into the cavities of decomposed organic remains, which they sometimes entirely fill up. These cavities are often globular or reniform, but sometimes there are little veins of three and four and even ten yards in length, and perhaps of an equal depth, and five or six inches thick. As I could only examine these superficially where they are cut through by the river, I cannot say, whether they contain any accidental minerals, but they contain some organie remains, of which the most numerous are Conotubularia Cuvierii, nobis, and C. Brongniartii, nobis. These organic remains, of which I have communicated a description, accompanied with drawings, to the Geological Society of France, have not, I believe, been observed in Europe. They characterize particularly these lower strata. Inever found these two fossils together in the same stratum; the C. Cuvierii seems more abundant than the other. They characterize a succession of strata of at least fifty feet in height, and Occupy the lowest part of those I have observed in Davidson county, namely the bed of the Cumberland river.

The next stratum is of more interest to the mineralogist. It contains veins of Sulphate of Barytes, of a crystalline structure, as at Nashville, below the creek which runs between the Rolling Mill and town. Above that creek we have a vein of Sulphate of Strontian, which produced some fine crystallized specimens of a fine blue color. It contains also, compact of Sulphate of Barytes, as near Haysboro,' where it serves as the matrix of the lead ore, of which I have spoken in one of my former reports; but it contains also cavities which are

very numerous in some places. These cavities are filled up with various minerals, sometimes several of them are found in one; and by examining a section of these filled up cavities, one can see in what succession these various fluids have permeated the limestone. In some we see that quartz entered first, and in that case, the sides of the cavity are lined with crystals of quartz; then the carbonate of lime has entered, and we find a deposite of crystalline carbonate of lime covering the quartz; the sulphate of lime has generally succeeded the carbonate of lime, and we find several varieties of that mineral in these cavities. (1) The Sulphates of Barytes and Strontian are amongst the number of the minerals which permeated that stratum, and which have filled up these cavities, giving occasionally beautiful specimens for cabinets.

The next stratum is one which I must consider as the uppermost in the vicinity of Nashville, and which is found only here and there, particularly at some of the highest spots; it is in some parts almost entirely composed of an accumulation of bivalve shells, being the Strophomenes rugosa, (Raf.) intermixed with Trilobites, Manon Piziza, Goldf., and some Encrinites, consisting of isolated flat rings from to of an inch in diameter. I found in this stratum two species of Escharia, which I consider as new, and which I have called E. ovato pora, and E. reticulata. In other places this strata is entirely composed of a conglomeration of fragments of various marine substances, as if the deposites of the sea shore were agglutinated; but these fragments have not been exposed to mutual erosion, as is the case with those on the sea shore, and which I have discovered, as mentioned above, in other strata of the vicinity of Tennessee. Even the most delicate fragments, such as Flustræ and Eschariæ, are perfectly preserved, and their texture and pores very distinct. I found among these fragments, besides the polypifers already mentioned, some univalves, which will be mostly enumerated in the report. This stratum seems more susceptible of disintegration than any of the lower strata; when fresh specimens are broken, they exhibit apparently a homogeneous rock with a compact structure, and no fossils are visible; it is only when exposed to the disintegrating action of the atmosphere that they come to light, and are finely separated from the rock, and so delicate are some of these fossils, particularly the Strophomenes, that they often break when taken between the fingers, and are in a degree great translucent.

(1) Sulphate of lime. If some deeper excavations are made in our limestone, we may discover some larger deposites of this mineral (generally called plaster of Paris when impure, and used in agriculture.) I found some of the finest varieties of it in Davidson county, the snowy gypsum, superior to any that I have seen, several varieties of compact and granular gypsum, of a beautiful white, and a very agreeable translucency; in an excavation by Mr. Litton near our town several large Jumps of the variety generally known under the name of alabaster were found. It is this substance which is used in Italy for making the handsome mantle ornaments which we see in the parlors of our elegantly furnished houses.

This stratum is wanting wherever currents have worn the surface of the country; thus I found it forming the upper stratum where the stone for the construction of the engine house for the Nashville water works was quarried; it is here soon lost, and the next following stratum is only visible as far as Brown's creek, where it makes its appearance again on the east side of that creek, forming the highest point between that creek and the low place in which the tan-yard of the late Col. Love is situated, and has here been cut through in constructing the Murfreesboro' and Nashville Turnpike. The current, which has formed the above mentioned low place, has washed away this stratum, and we find it again towards the east of the bridge, where it runs under the ground. We find it handsomely displayed near the bridge between three and four miles from Nashville where the old banks of Mill creek, which now runs several rods towards the east, are visible, and where that current has denuded the present strata.

The above description of the strata which is found near Nashville, is applicable to nearly all the strata of limestone which are found in Middle Tennessee, they are characterized by the same fossils, and the same mineralogical accidental substances are occasionally found every where.

West, or rather south-west from Nashville, the limestone is covered with conformable strata of shale, or slate as it is generally called.This stratum, which is found in nearly every county of Middle Tennessee, is what mineralogists call aluminous slate, it is mostly of a black color, often penetrated with bitumen, even sometimes containing small veins of solid bitumen, from which circumstance it was often mistaken for coal, and large sums of money have been spent in search for this combustible in such situations. This stratum is sometimes replaced by a bed of indurated clay of a brown color variegated with gray and red. The thickness of the stratum of slaty clay, and the replacing indurated clay, varies from eight to nine, (as I have seen it near the Harpeth river, and near Marrowbone and Sycamore creeks) to twenty or thirty feet as it is found at some places in Maury county. I found, as I have said before, no organic remains in the stratum of slaty clay. This is not the case with the indurated clay, it contains Encrinites and Polypifers. Near the Harpeth Bend, where this clay exists, I found some organic remains resembling more or less the orbulite lenticulata, Lam., and a beautiful specimen of the Calamopora spongites, var., tuberoso-Goldf. about seven inches in diameter--it was calcareous, I found a similar fossil about ten feet lower, which was silicious.

The stratum of slaty clay is covered by a stratum of limestone, which is, in some places, composed almost entirely by encrinites. Several species, or perhaps genera, have contributed to the formation of that stratum. I have collected as many crowns of these animals as will constitute perhaps fifteen species, the description of which will be published, with engravings in future; they are intermixed with Spirifer cuspidatus, S. attenuatus, and several species of Gorgona, Flustra, and Turbinolia. In some places these petrifactions are agglutinated by a chloritic substance; in others they are imbedded in a very fetid

granular limestone, forming in that case a beautiful marble, when cut and polished. The different spots and figures brought out by the sections of the Encrinites and other organic bodies form a pleasing variegation. The petrifactions in this stratum are mostly calcareous, often spathose, but they are in some places all siliceous, of a calcedonic nature.

This encrinital stratum is covered sometimes with a stratum of sandstone, upon which follows again a similar stratum of encrinital limestone. These encrinital strata are from ten to twelve feet in thickness-in some places they are wanting.

The whole of the various strata which I have described, is covered with a siliceous stratum of one hundred and fifty to two hundred feet in thickness, which forms the highest levels of Middle Tennessee, and of which I have already spoken. This stratum is of a very heterogeneous nature, and although principally belonging to the siliceous sand sandstone, it nevertheless passes here and there into argillaceous sandstone. Part of it is composed of small, often very fine and uniform grains of quartz or sand, rarely containing any argillaceous or ferruginous cement-nor does it contain any intermixed mineral.Its color is mostly gray passing into yellow or brownish orange.The texture, which as has been stated, is sometimes granular, often passes into the earthy without losing its siliceous nature, having in that case very much the appearance of tripoli, and may be used for the same purposes for which tripoli or rotten stone is used. It assumes often a slaty structure; it also passes into chert, or hornstone--in some places, as on both sides of the Cany Fork, the whole of the stratum has assumed this state.

I have not seen any petrifactions in the granular or sandstone part of the stratum, but they abound in those seams or veins which have something like an earthly appearance, or rather which have asassumed the nature of chert, and which also occur in streaks or veins, or sometimes constitute the whole stratum. The lowest part of the stratum, where it is near the encrinital limestone often contains members of Encrinites, and other fossils of that stratum, and are invariably of a calcareous nature. This shows that the formation of those siliceous strata, is more or less contemporaneous with the encrinital strata. But a few feet above the junction of these strata, no encrinites, nor any organic remains are perceptible; nor are there any fossils for the distance of many feet, but as soon as the rock becomes more compact, particularly when it begins to assume the appearance of chert, the organic remains begin to abound. A few Encrinites again become visible, also some Trilobites, but the fossil which particularly characterizes the stratum is the Gorgonia antiqua, Goldf., accumulations of which, deposited in a direction parallel to the stratum, form, for some inches, sometimes even more than a foot in thickness, the whole rock. When this Gorgonia is found in the softer kind of rock, it forms one of the most delicate organic remains, the rock being a brownish orange yellow color, while the delicate capillary tubes with their transverse junctions, are white, so that when freshly broken in the direction of these poly

pifers, it exhibits a fine white reticulated structure upon a dark ground; but as these delicate tubes, which are not thicker than a sewing-thread, are not firmly fixed upon the stone, they are destroyed by the least friction. This is not the case with the Gorgonia found in that part of the sandstone which has the nature of chert, which in some places also abounds in Gorgonia of different kinds, among which G. antiqua. Goldf., and the G. infundibuliformis, Goldf., prevail and they are mostly siliceous, hard and firmly attached to, and sometimes even incorporated with the rock, which is often entirely composed of similar polypifers; and when it happens that a block of it is broken in the direction of these fan-shaped structures, it forms beautiful specimens, the stone having generally a brownish yellow color, while the fossil remains white.

I do not recollect ever to have seen any of these fossils in European sandstones, nor have I seen it mentioned in any of the authors on geology. In Davidson county we find them in many places where the sandstone prevails; they are associated with Trilobites, and members of Encrinites and Flustras-I found also among them a few crowns of Encrinites. This stratum also contains an organic substance which is composed of a flat stem--perhaps an Alga(?)

This stratification continues nearly uninterrupted, except, where it is cut through by currents, to beyond Tennessee river. It is in this siliceous stratum that the rich deposites of iron ore (hydroxide of iron) are found which supply ore to the furnaces in Dickson, Stewart, Hickman and Perry counties. The Tennessee, and most of the other rivers in these counties, have cut through these upper strata, and their beds limestone, some of them similar to that in the vicinity of Nashville.

The upper strata of the limestone in the vicinity of the Tennessee river differ from those mentioned above, for as far as I have been able to trace them, they cover the limestone strata of Davidson county, and differ also in a mineralogical point of view, being more of a marly nature, containing only 87-100 of carbonate of lime. They are more susceptible of decomposition, and have an argillaceous smell when moistened; but they contain the organic remains which are considered by the geologist as characterizing the lowest of the transition strata, as Trilobites, Calceola sandalina, Catenipora, Orthoceratites, Calamopora and many others.

This limestone which comes to light at several places near the Tennessee river, on both sides, and which are remarkable for the sterility of their soil, are there called glades, and are towards the west, or southwest, covered with strata of marl, in which numerous Grypha, Ostreæ, etc. are found, (my third report contains a description of this marl and its effects upon vegetation.) This marl is covered with sandstone which contains lignite, petrified wood, pyrites, and retinasphaltum, upon which follows a ferruginous sandstone, in several places rich in iron, and the whole is covered towards the Mississippi with an allu

vium.

In order to make the general view of the geology of the State more intelligible, I have joined a geological map, on which all the different