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THE MARBLES.

In Iron county, the distribution of the marbles is confined to the territory drained by Marble creek and the head-waters of Stout's creek. No well-directed effort has been made to develop these marbles, but several partially successful attempts have been made. The chief reasons for their discontinuance have been: the distance from railways, thinness of strata, frequent seams and blotches of green and brown ferruginous clays, which weather out on exposure, and a tendency of the stone to "pluck" in a damaging way under the tools of the stonecutter. In spite of these numerous drawbacks, there are, however, places where well-conducted quarrying might be profitable.

Sarah P. Childers.--In township 34 N., 3 E., section 35, southwest quarter, are two or three very small openings in the out cropping marble, which were made many years ago, and are not now worked. The marble occurs in a hill which occupies an area of many acres. The hill slope is covered mostly by a thick mantle of residuary products and detrital matter; but at several horizons marble beds crop out, and it is probable that they have a total thickness of many feet. Individual strata 18 inches thick were observed. The stone has a gray color, and is mottled and streaked with green and yellow. Some of the mantelpieces in the Capitol at Washington are said to have been taken from beds here exposed.

The exposure of marble on the Kramel land, described on page 30 of this report, closely adjoins the last, and is apparently similar in character and mode of occurrence. In addition to these localities Mr.

Haworth describes the following:

About a mile up the creek from the Childers quarry, at the Dennis Reagan place, lining the north bank of the creek for a few hundred yards, are three or four layers of marble, one above the other in limestone order. A large porphyry hill stands near by to the north, so that the marble cannot be very extensive. Fragments of porphyry frequently occur in the marble and other impurities are common, so that but little can be hoped for from this place.

A second place is on one of the upper tributaries of Marble creek, along the boundary between sections 19 and 30, in township 33 N., 4 E. Here is a very white marble, but its extent could not well be determined. Probably it covers only a few hundred yards square, but

possibly it is more.

A little work has been done at two points, neither of which was extensive enough to show much more than can be seen on the surface.

THE SANDSTONES AND CONGLOMERATES.

The sandstones of this region are often saccharoidal, and are mostly stained yellow or red with ferric oxide. They disintegrate most easily and are unfit for building material, although they have been used by the railway company in constructing bridge abutments, and, locally, for door and window-sills.

Several varieties of conglomerate and breccia are found, most of which are not now in their proper geological horizon, but exist only as boulders scattered over the hill slopes. The contained pebbles are mostly limestone, while the cementing material varies, being in different localities, lime, silica, and limonite respectively. On Pilot knob and Shepherd mountain there occurs a porphyry conglomerate in which the pebbles (often large enough to be called boulders) are porphyry, as is also the cementing matrix. This rock was quarried locally at Ironton, but was found to be not durable, disintegrating very rapidly.

Shepherd Mountain.-On the southern slope of Shepherd mountain is a small quarry in a porphyry conglomerate which grades into a coarse sandstone. From 2 to 10 feet of stripping of clay and boulders covers the rock. The stone is easily quarried and dressed, but that from this locality disintegrates very rapidly on exposure to the weather, and is practically worthless for building purposes. The output, which has been very small, has gone to Ironton to be used for foundations. Some of the steps of the Iron county court house are of this stone and these are very deeply worn, compared with those of limestone with which they are associated. This is the same quarry as is described on page 3 of this report.

Sandstones of similar character have been quarried near Iron Mountain, and are referred to on pages 42 and 43; also between Pilot Knob and Middlebrook, as stated on page 31.

THE CLAYS AND SANDS.

In the area here discussed no sedimentary clays have been observed excepting such as have 'resulted from local washings from the hill-sides; but of residual clays there are very extensive beds, pro

ducts from local decomposition of the rocks, which vary in thickness from a few inches to 70 feet or more.1

No deposits of kaolin or of other exceptionally valuable clays are known to exist, the prevalent material being only adapted to the manufacture of ordinary brick or drain tile. The only demand for bricks is the local one, which is extremely small; consequently the industry has been carried on only in a desultory way. The material used is a clay residuary from magnesian limestone, but it is fit for use only to a depth of about 18 inches, where, having been weathered and leached by rain-water, it is in a condition to make a fair quality of brick which burn to very dark colors. The clay is sticky and much sand is required in moulding it, which is probably the reason for the failure of several brick-making machines which have been tried in Iron and Madison counties.

In Iron county, brick has been made at Ironton, Iron Mountain, Middlebrook and Arcadia. The total product amounts probably to not over 6,000,000 bricks.

Sands are found in abundance along the many water-courses where they are very accessible. They are of value for building purposes, and also as road material. The friable sandstones as exposed at the

described localities are also good sources of sand.

THE LEAD ORES.2

As already referred to on page 54, lead ore is mined at Doe Run in the northeastern corner of the sheet, but will receive notice in the report on the Mine LaMotte sheet. Diamond drill holes put down in the Belleview valley, near Graniteville and near Ironton, have failed to reveal the presence of ore bodies, so far as the writer has been able to ascertain. Thus, though the limestones of the Belleview and Arcadia valleys belong to the same formation as those at Doe Run, they are not generally ore-bearing, and the results of examinations so far are adverse to the existence of workable ore-bodies here or elsewhere within the limits of the sheet.

1 See Geol. Sur. of Mo. 1872, p. 13. Raphael Pumpelly.

2 By Arthur Winslow.

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