James's Account of S. H. Long's Expedition, 1819-1820, part 4

by Edwin James; Stephen H. Long; Thomas Say

The hot springs of the Washita issue from clay-slate, and if we may judge from the inclination of the strata, and the distance at the surface from the granite of the cove, we may conclude a very large mass of clay-slate is interposed between the surface of the granite and the point at which the springs rise. This however it is not possible to ascertain. The hottest springs on the globe rise from beneath or within the granite,[87] and it is not improbable this rock may approach near the surface at many points {309} in the Ozark mountains, where it has not yet been uncovered.

The slate rock about the hot springs is highly inclined, often a good deal flinty in its composition, and as far as we have observed, contains no organised remains. It is traversed by large upright veins, filled usually with white quartz, contrasting strongly in colour with the dark blue of the slate-stone. The elevation of the "Hot Springs mountain" is estimated by Hunter and Dunbar at three hundred feet above the surface of the creek at the springs. This point is probably raised twenty or thirty feet above the Washita at Keisler. North of the springs the slate-rocks rise to greater elevation; but it is not probable that at any point where we have seen them, they attain the height of one thousand feet above the Mississippi.

The high lands between Washita and Red river are occupied principally by sandstone, the clay-slate appearing to extend from north-east to south-west, which, as far as we have observed, is the direction of the strata; these, when they are not perpendicular, usually dipping to the north-west.

The country about the sources of the Washita is represented as affording many interesting minerals; among them are enumerated "a martial pyrites, large bodies of crystallised spar, and hexagonal prisms, which are known to contain no small portion of the precious metals."[88] If the clay-slate in any part of this mountainous region should be found accompanied by its usual attendant, the metalliferous limestone, we should be more ready to credit the accounts of the precious metals being found, as at least some of the valuable mines in America exist in that stratum. But as yet we have no satisfactory accounts of the occurrence of that limestone, or any of the precious metals in that part of the United States.

{310} Granite.—About fifteen miles south-east from the hot springs, near the Washita, granite is found in situ. It forms the basis, and, as far as we could discover, the whole mass of a small hill, but little elevated above the level of the river; we found it emerging from beneath the soil at several parts of an area for two hundred or three hundred acres; but had not an opportunity to trace it to any great distance, nor to observe its connection with any other rock. The extent of surface which it covers, we believe, cannot be very great. This granite is very soft, and disintegrates rapidly when exposed to the air. It is compounded of grayish-white quartz, yellowish-white felspar, and an unusually large proportion of mica, in variously and brilliantly coloured masses. These large laminæ of mica are white, pearl colour, yellow, brown, green, and often black, and in some instances are so large and numerous as to exceed in proportion the other ingredients of the aggregate. Talc also enters in large proportion into the composition of this granite. It is indeed sometimes so abundant as to occasion a doubt whether the whole should not be considered a bed of talc, rather than granite. This talc is in tabular masses, two or three inches in diameter, and about half an inch in thickness. Zeolite is also so abundant as sometimes to seem to take the place of the other materials of the granite. It is of two varieties, radiated and mealy. Stilbite (blaettriger zeolith of Werner) occurs in connexion with zeolith. The bed of one of the small streams which traverses this formation of granite is paved with small crystals of schorl, that of another with native magnet. Sulphuret of iron is disseminated in the granite. Several of the appearances presented by this interesting mass of granite, would seem to countenance the opinion that it is of secondary origin, like that mentioned by Saussure, as existing near the valley of Valorsine, at Semur en Auxois, and at the city of Lyons. In speaking of the granite {311} at these places, he says, "It could not be doubted on seeing these heaps of large crystals, that they are the produce of the rain-waters, which, passing through the granite, have dissolved and carried down these different elements, and have deposited them in these wide crevices, where they have formed new rocks of the same kind. The crystals of these new granites are larger than those of the ancient, on account of the repose which the waters enjoyed in the inside of these reservoirs."

The granite of the Washita, if it is to be considered as of secondary formation, appears to be much more extensive than any of the kind hitherto known. Many more particulars must, however, be ascertained before this question can be settled. We are ignorant of the manner of its connection with any other rock. Nor do we know of any formation of primitive granite from which it could, by the action of water, have been derived. One can have no hesitation, however, in considering the Ozark mountains, as a separate system within themselves, and having no immediate connection with the Alleghanies or Rocky Mountains. The sandstones which lie about these mountains, abound much more in mica than those near the Rocky Mountains, nearly in the same proportion as the granite of the latter has less than what is met with in the little we have seen of the former. The Ozark mountains exhibit evidence of metallic riches far exceeding any thing that appears in the Rocky Mountains. May not an extensive range of granite and other primitive rocks have existed at some distant period where the Ozark mountains now are, containing the vast quantities of the ores of lead, iron, &c. now found in rocks of recent secondary origin, and even in the alluvial? and may not the operations of water during many ages, when an ocean rolled over the summits of these mountains, have worn down those primitive rocks, their detritus having been deposited horizontally upon their submarine sides and summits; {312} so that the greater part of their surfaces are now covered by secondary aggregates? Our acquaintance with this range is however much too limited to admit of indulgence in such speculations.

Numerous specimens of minerals brought by Lieutenant Graham and Dr. Somerville from the Upper Mississippi and the Illinois rivers and others from that region, now in the possession of Dr. L. C. Beck, of St. Louis, have a peculiar resemblance to similar minerals met with in the Ozark mountains, south of the Missouri. From these resemblances, and the corroborating testimony of all the accounts we have received concerning that country, rich in mines, which lies along the eastern side of the Upper Mississippi, we have been induced to believe that a continuation of the Ozark mountains, or at least, of a region similar in Mineralogical features, extends from the confluence of the Missouri, northward to the sources of the Wisconsan, and the Ontonagon river of Lake Superior, north of the Missouri, the country is very little elevated; but aside from this it appears to possess all the peculiar features of the region we have been considering. The sandstones, the limestones, and other rocks, have a striking resemblance. Both regions abound in the ores of lead, and both afford copper.[89]

We are aware that the great irregularity in the direction of the ridges accessory to this range, and of the dip and inclination of the older secondary rocks belonging to it, may be considered objections to our idea of the connection and continuity of the different parts and the general direction of the group. But we are by no means anxious to maintain the position we have assumed. Our examinations have been limited, and we shall rejoice in any opportunity of correcting our errors, and enlarging our acquaintance with this interesting range of country.

{313} We subjoin in a note some account of a few of the most interesting minerals hitherto observed in connection with the rocks of this district.[90]