Art. IV. Sketch of the Geology and Mineralogy of a part of the State of Indiana.
Art. IV. Sketch of the Geology and Mineralogy of a part of the State of Indiana, communicated in a letter to the Editor, by Mr. W. B. Stilson.
Louisville, (Ken.) August 11, 1818.
Dear Sir,
I have employed a short period of leisure in passing over a portion of the state of Indiana. Among other objects, I was not wholly inattentive to the mineralogical and geological features of the country. I now, with diffidence, transmit to you the result of my inquiries.
Sketch, &c.
The secondary formation of the state of Indiana is abundantly evident. The surface of the soil is undulating, and marked with few elevations which deserve the name of mountains. The rocks are sandstone, limestone, and clay-slate; all of which are disposed in horizontal strata. The sandstone presents nothing remarkable in its appearance. Its colours are various shades of gray and brown. The principal hills are of this formation. The principal colours of the limestone are blue and gray, and their various mingled and intermediate shades. Its secondary formation is very manifest from its almost earthy appearance. In innumerable instances, the limestone rocks contain immense quantities of imbedded shells, of great similarity in form and appearance, and having considerable resemblance, to the common escallop-shell of the ocean. Owing to the easy decomposition of these rocks, and the horizontal position of their strata, they afford many subterranean passages for water. A considerable stream, called Lost River, runs into a cave in the side of a precipitous hill; and, after a passage of 6 or 7 miles under the earth, again makes its appearance, with a large accession to its waters. The traveller's attention is continually excited by cavities in the earth, where the temporary rivulets, proceeding from rains, make a sudden exit through perpendicular perforations in the upper stratum of the rock. There are many such cavities, which do not receive any water from the surface. Some of them are many yards in diameter, forming a regular circular concave, of considerable depth towards the centre. They are vulgarly known among the inhabitants by the name of "sink-holes." The localities of slate are few, and present nothing uncommon.
With regard to the particular minerals. On Sand Creek, 60 miles from White River, is an interesting locality of that variety of silex, commonly called burrstone. It has been examined by several practical millers, who do not hesitate to pronounce the specimens which it affords, equal, if not superior, to the French burrs. The locality is twenty acres in extent, and appears to be inexhaustible. The mineral varies very much in its appearance; it is generally porous, and appears to have been puffed up by the escape of some gas, while it was in a state of fusion. A mass of well-raised bread gives no inadequate idea of its configuration. It produces most vivid sparks with steel. Some labourers are employed in procuring millstones from this place; and, such is the size of the siliceous rocks, that they are under no necessity of constructing them of detached masses. They form, of a single rock, millstones of five and a half feet in diameter, which are not defaced by any irregularity, or even earthy cavity. These millstones may be carried down the White, Wabash, Ohio, and Mississippi rivers, to New-Orleans, with great facility. And if they should prove as excellent as it is expected they will, this discovery will shed new lustre upon the accumulating evidence of the mineralogical resources of this republic.
Many other varieties of silex are common: rock crystal, agate, and chalcedony, are often found in the beds of rivulets. I passed a considerable distance upon the banks of a small stream, called Leather-wood creek: the bottom of the creek was covered, the whole distance, with siliceous masses, shaped like oblate spheroids, and of every size, from that of a large melon downwards. On being broken, they presented beautiful geodes of crystallized quartz, amethyst, &c. The outside was often fine chalcedony, and sometimes the interior was the same substance, in the form of balls; all these were sometimes combined, forming agates of great beauty.
Carbonate of lime, crystallized, is sometimes found; and many of the caves afford fine stalactites.
There is a large cave near Corydon, celebrated for the production of sulphate of magnesia, or Epsom salts. It has been explored for the distance of several miles. When it was first discovered, the bottom, in many places, was covered to the depth of several inches, with pure, brilliant, needle-shaped crystals of sulphate of magnesia. By some mysterious process of nature, or rather of Divine benevolence, the production of this useful salt is continually going on. This cave also produces some other salts in small quantities: nitrate of lime, nitrate of magnesia, sulphate of lime, &c.
Where the basis of the country is limestone, the waters always take up a great quantity of lime, and some of them possess great petrifying powers. I saw many specimens of petrifactions: a tuft of moss, the form perfectly preserved; leaves, bark, and branches of trees; insects, and many others.
Many of the springs are strongly impregnated with sulphur, and some of them are saturated with sulphuretted hydrogen. I found the opinion universally prevalent among the people of this state, that the first appearance of these sulphur springs was immediately subsequent to the earthquakes of 1812. They say, that then new springs, impregnated with sulphur, broke out, and the waters of some old springs, for the first time, gave indications of this mineral. A sensible farmer, who has a large sulphur-fountain, boiling up from the bottom of a river near its bank, assured me, that there was no trace of this spring until after the period to which I have alluded. He could have no interest in deceiving me; and if he did deceive me, his conduct could originate only in that love of the marvellous which is so characteristic of the human mind. He moreover assured me that the "water had been growing weaker, (to use his phrase) ever since its first appearance." I have room only to mention, among the minerals of Indiana, many varieties of clay, ochres, gypsum, alabaster, muriat of soda, (very common,) iron ore, and antimony.
Art. V. New localities of Agate, Chalcedony, Chabasie, Stilbite, Analcime, Titanium, Prehnite, &c.
Art. V. New localities of Agate, Chalcedony, Chabasie, Stilbite, Analcime, Titanium, Prehnite, &c.
Deerfield, &c. In the account of the Mineralogy and Geology of Deerfield, by Mr. Hitchcock, in the present Number, it will be seen, that these interesting minerals (with the exception of titanium) exist in the secondary greenstone of that place. We have specimens, (through the kindness of Mr. Hitchcock,) and observe that the agates, chalcedony, analcime, and prehnite, are imbedded in the trap; the agates are in some instances very delicate in the disposition of their bands, and need nothing but polishing to make them beautiful; the same is true of the chalcedony. The chabasie and stilbite occupy cavities, and the chabasie is often distinctly crystalized in a rhomboid, so nearly approaching a cube, in the quantity of its angles, that the mistake is easily committed of supposing them to be cubes; the crystals are sometimes transparent, and the largest a quarter of an inch in diameter. Titanium is found in Leyden; it is the red oxide—very well characterized—in reddish brown crystals as large as a common goose quill,[18] and, in some instances, perfectly geniculated. It is rare to see finer specimens.
East-Haven. It will be observed, that the great ranges of secondary greenstone, which cut Connecticut and Massachusetts in two, terminate at New-Haven, on the one hand, and some way above Deerfield on the other. By comparing the account of the termination at New-Haven (Bruce's Journal, v. i. p. 139.) with that now published, of the termination at or near Deerfield, it will be seen that the geology and imbedded minerals are very similar. At East-Haven, (one of the branches of the greenstone of New-Haven, and within from three to four miles of the latter town,) chalcedony is often found, sometimes imbedded in the trap, (but perhaps more frequently loose among the fallen stones,) which, although in small pieces, is as perfect in its characters as the chalcedony of the Feroe Islands. It is of a delicate gray, translucent, mamillary, botryoidal, stalactitical, or impressed by crystals of quartz, which have usually fallen out; sometimes these crystals incrust the chalcedony.
Agates also are found in considerable numbers, both imbedded and loose. They usually consist of bands of chalcedony and quartz, and sometimes of the latter only, variously striped or spotted, or interlaced with jasper, carnelian, and cacholong.
The form of the imbedded agates at East-Haven is commonly ovoidal, or egg-shaped, and frequently it is conical. Some portions of pure chalcedony occur, which are shaped like a long, slender carrot or parsnip, and the situation of the latter in the ground would exactly represent that of the chalcedony or agate in the rock.
The imbedded masses are frequently altogether quartz, and then they are most commonly geodes or hollow balls lined with crystals, commonly very perfect and brilliant, although rarely large. These crystals are commonly transparent and colourless—but they exhibit also most of the varieties of colour which quartz assumes—the amethyst—the smoky—yellow, &c., and occasionally they are tipped and spotted with red jasper.
The spontaneous decay of these trap rocks causes many specimens to be found among their ruins, and many more are imbedded in the solid rock; but the industry of successive classes from the neighbouring college, issuing from Col. Gibbs's cabinet, has now made specimens more scarce.
Woodbury. Twenty-four miles from New-Haven, N.W.
In a geological sketch of parts of the counties of New-Haven and Litchfield, which may appear in a future Number, it will be seen that prehnite, stilbite, and agate are found at Woodbury, in the little basin of secondary greenstone which exists there; the prehnite is abundant—it is not known whether the agates are so, although it is asserted to be the fact; the stilbite was not observed to be abundant, although it was well characterized.