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CHAPTER XII.

Observations on the Geology of the Missouri Mines. Of the Granite Formation. Of the Inferior Limestone. Of the Crystalline, White Sandstone. Of the Compact, or Superior Limestone.

"A COUNTRY," it is remarked by Dr. Mitchill, "which once raised the highest expectations in France, and caused one of the most memorable disappointments that ever Paris or Europe knew, cannot now be viewed with indifference. The lead mines, beyond the Mississippi, are connected with our political security and national independence. Every fact concerning them ought to be known, such as the kind of ore, the matrix in which it rests, the mode of raising it, the process of smelting, the product per centum, the price of the pure metal at the mines, and in the market, and other analogous information. Those mineral beds appear, from the accounts I have received, to be the most abundant deposites of lead that the globe contains. They will be sources of security and wealth to future generations. Indeed, it is impossible at this moment to calculate their .value."*

*MS. communicated in 1819.

How far these requisitions were fulfilled, and the character and value of the western mines, elucidated by our publication on the mineralogy and geography of those mines,* it is not our purpose to inquire.

As it has been found somewhat difficult to form clear conceptions of the geological features of this section of country, from the notices which we incidentally presented in the work referred to, and as the subject, apart from all theoretical speculation, has an important connexion with the present and future condition of an extensive and interesting mining district, we shall embrace the occasion of the present visit, to recapitulate a few of the leading facts heretofore mentioned, and to add such farther particulars, in illustration of the position of these mineral repositories, as have resulted from subsequent examination and reflection. On these observations, we enter the more readily, as no more formal and extended description has been offered in the interim that has elapsed between the date of our former and present publications: nor can we affirm that we are wholly uninfluenced by a wish to satisfy the just requisitions of a temperate criticism,† by explaining what was before doubtful or obscure; and, in some measure, to merit the commendations of a generous one‡ by perfecting what, we are free to confess, was but imperfect. In performing this act of justice to ourselves, we do not aspire to be the reviewers of our cotemporaries, nor hold ourselves responsible to reply to any observations, from whatever source, which we conceive to be dictated in a cavilling or polemical spirit.

The portion of country to which we shall chiefly

* View of the Lead Mines of Missouri.

† American Journal of Science, Vol. III, No. 1. New-York Literary Journal, Vol. III, No. 1.

confine our attention, comprises the four* mining counties of Missouri; an area which extends from the right bank of the Marameg about one hundred miles towards the south, and has a medium breadth of forty-five or fifty miles. It is not here designed to convey the impression, that there are any political divisions circumscribing such an exact portion of country, or that fragments of contiguous counties may not be included within the boundaries mentioned; but our principal object, in this definition, is sufficiently and fully to circumscribe the district of the mines; to the elucidation of the mineralogy of which, we wish to render the present remarks strictly subservient.

The most prominent feature in the mineral aspect of this district, results from that natural division of the country into confused groupes of hills, separated by small valleys, and drained by one or two principal rivers;-whose minute ramifications spread throughout every part of the district, and render it at once one of the most airy and best watered portions of Missouri. There is such an identity of features in the unreclaimed parts of this district, and so close a resemblance in the soil and forest growth, that oftentimes it is difficult to discriminate; and the vast body of mixed alluvion, which spreads with nearly a uniform depth over every inequality of surface, precludes the observer, in a great measure, from making the most satisfactory researches respecting the nature, the direction, and the mutual coincidence of the strata. These strata, however, crop out on several eminences, and are occasionally disclosed

* The late incorporation of the county of St. Francis, from parts of St. Genevieve, Washington, Jefferson, and Madison, renders it necessary to add this new county to the number of those which are characterized by containing lead mines. Mine a' Joe, Bryant's mines, &c. are within this new county.

by the deep cuttings of some of the more considerable streams, and particularly by the Marameg and the Mississippi; the latter of which presents an interesting section of the outskirts of the lead mine district, in the direction of its longitude. There are also some excavations that have been carried, in the search for ore, to such a depth, as to afford some light to the geologist in determining the structure of the country; although there is less aid to be derived from this source, than might reasonably be expected, when we recollect the very considerable period that has elapsed, since the country was first exposed to the labours and scrutiny of miners.

From an inspection of these features, so far as our opportunities have extended, and by applying the facts according to the inferential method so much in vogue, it appears manifest, that the whole district is chiefly divided, by limits which we shall endeavour to point out, between the primitive and the secondary formations.* That the rocks of the latter class, both sandstones and limestones, in many places, assume that semi-crystalline structure and translucence which are usually employed to mark the transition era, we think must also appear evident to every observer who shall examine the geology of this district with a scrupulous attention. Such is the predominant character of the limestone, which is the lowest rock, found in place, in the district under consideration. This stratum seems to be intimately connected with the sandstone, whose limits it appears in many places to invade, for a considerable extent, creating an alternation and intermixture of the two varieties, which it is perhaps not difficult to account

* We use the term formation, as signifying a succession of strata, or a continuous bed of rocks, composed of similar materials, and of considerable, but indeterminate extent.