sistent and probably co-extensive with the associated coal. Examinations beyond the limits of the sheet south westward indicate its presence outside of the area where the Bevier coal is known to exist. The limestone is quite fossiliferous, usually abounding in Spirifer cameratus, Athyris subtilita, Chonetes mesaloba, Productus costata, Zaphrentis and other forms. The lower layers are commonly more regularly stratified, while the upper consist, for the most part, of irregular concretionary nodules of limestone imbedded in a marly clay. Lower Ardmore Coal.-The Ardmore limestone described above is underlain by from 25 to 30 feet of argillaceous and bituminous shales, sometimes sandy, and with a few thin beds of limestone interstratified. In the shales above the coal intermittent beds of bituminous limestone frequently occur. The coal of this horizon is the lowest exposed in the vicinity of Ardmore. No known outcrops are found outside of the valley of East fork. It is overlain by from five to six feet of black fissile shale containing ovoid nodules. These have given occasion for the mistake of identifying this shale with that overlying the Macon City coal, where similar nodules also occur; 1 but in the latter case they are usually larger and more conspicuous. The shales seem generally to be overlain by limestone from six inches to three feet thick, but its prevalence was not satisfactorily demonstrated. At the Eureka shaft 11 feet of clay is reported underlying the coal. The coal is sometimes divided by a varying thickness of clay and shale. No attempt has been made to mine this coal, as it does not seem to promise profitable results. 2 A discussion of its economic value is therefore omitted, as is also that of the Summit coal, for a like reason. Eureka Coal.-There are no exposures of the strata below the Lower Ardmore coal within the limits of the sheet, and our only knowledge of these is based upon the record of the Eureka shaft. That record shows the clay underlying that coal to be followed by 44 feet of alternating beds of sandstone, shale and clays, below which is a seam of coal of doubtful extent and 1See Geology of Macon County, by Wm. J. McGee. Trans. St. Louis Acad. Sci., Vol. V. pp. 322 and 323; also sections 7, 8 and 10 on plate. 2 At Eureka shaft an entry is now being driven to ascertain if it can be worked with profit. Report State Mine Inspector 1891, p. 51. divided into two benches by a clay seam varying in thickness from six inches to five feet. The coal is impure and roof poor, The full bed is about 6 feet thick, of which 3 feet is coal. This is the only known occurrence of this coal, and is probably a local deposit. The deep drilling made at Macon City shows no coal at this horizon.1 Some attempt has been made to operate this bed here, but it has not been attended with success, owing largely to the poor character of the roof. The following sections include the exposures of Lower Coal Measure rocks seen within the sheet. Additional details appear in the preceding typical sections and under the eco. nomic discussion of the Bevier coal. East Fork Sections. In the northern part of the sheet no exposures of the Lower Coal Measures appear along East fork. A general section representing the exposures at Ardmore is given on page 16. At several places northeast of the store the Ardmore limestone and Lagonda shales outcrop along the stream. About half a mile northeast the shales overlying the Lower Ardmore coal appear in the west bank of the stream. G. C. Broadhead gives a section from this locality, which is here inserted: Section VI. SECTION ON EAST FORK, One half mile northeast of Ardmore (S. W. N. W., Sec. 19). FT. IN. Interval to top of Lower Coal Measures about 20 feet. 1. Slope, concealed 3 2. Limestone, thick bedded, bluish gray; breaks in nodular masses. 3. Slope, concealed. .... Interval to base of Lower Coal Measures about 90 feet. 1 This hole was put down to a depth of 1000 feet. It shows 185 feet of Coal Measure strata in which there is a noticeable absence of all the coals below the Macon City bed. The limestone (No. 2) of this section is evidently the Ardmore limestone, while the coal and interbedded shales below represent the Lower Ardmore coal. The base of the section is at the surface of low water in East fork. Just above this locality the Bevier coal is worked at Walter's bank. Its altitude is here 755 feet, showing that it comes in immediately above the preceding section. It is here four feet thick and is overlain by sandy shales. At the Ardmore bridge over East fork, black shales, said to be underlain by coal, appear in the bed of the stream McGee' gives the following section from this locality: Section VII. ARDMORE BRIDGE SECTION. 1. Drift.... FT. IN. 10 2. Limestone, heavy, bedded in discontinuous ledges, generally pure but sometimes magnesian 4 5 4. Coal (Lower Ardmore Bed).. 1 6 3 3. Shale, thinly and smoothly laminated, with ovoid nodules 5. Fire-clay, light blue, extending to bottom of channel. This coal probably represents the upper bed, No. 5, of Section VI. The thickness of the limestone, No. 2, is accepted with doubt. At the railway cut three-fourths of a mile south of Ardmore, a ten-inch layer of limestone, underlain by 10 feet of clay shales filled with iron nodules, is seen. The Bevier coal comes in several feet above this. Farther on tumbled masses of limestone appear at the side of the track, apparently derived from the Ardmore limestone. On the road to Excello, the Lagonda sandstones and shales appear in the hillsides at several places. South of Ardmore the Bevier coal has been drifted into at numerous points along both sides of the stream. Most of these localities are indicated upon the map, and need not be described here. On Beecher creek the Bevier bed appears in the bed of the creek, in the following section: 1 Trans St. Louis Acad. Sci., Vol. V., p. 323. Section VIII (No. 6 of Section sheet). BEECHER CREEK SECTION (N. E. N. E. 1, SEC. 2). Altitude at top of section about 790 A. T. Interval to top of Lower Coal Measures about 16 ft. 1. Shales, sandy. Exposed..... 2. Coal, more or less broken and disturbed; with included clay 3. Concealed (about)...... 4. Limestone, nodular with fossils. Exposed 5. Shales, sandy. Exposed.. Total thickness It is noticeable that the altitude of the coal is here considerably greater than at Ardmore. About two miles southeast of this, in the N. E. Sec. 6, the Lower Ardmore coal appears somewhat above the level of the East fork; it is here 18 inches thick. About three-quarters of a mile southwest is an abandoned drift on the same horizon. In the southeastern corner of the sheet, at J. T. Cooley's drift, A. Winslow obtained the following section of the air-shaft: Section IX. J. T. COOLEY'S DRIFT (S. E. 1, N. E. 1, Sec. 5). About a mile northeast of this, a well at 775 ft. A. T. This last section was taken outside the limits of the sheet, but is inserted here to supplement the preceding. Middle Fork Sections. In the upper part of the sheet no exposures were observed along Middle fork. At Bevier the coal is reached at from 50 to 160 feet, according to the location of the shaft. The general character of the Lower Coal Measure strata here may be seen by reference to Section II, page 15. At Loomis and Snively's shaft No. 4, the drill was put down 21 feet below the coal, with the following results: Section X. RECORD OF LOOMIS AND SNIVLEY'S SHAFT No. 4 ( mile east of depot ). Altitude at top of shaft about 785 feet A. T. 1. Old shaft; no record, coal at bottom, with inch clay seam averaging 4 feet in thickness 5. Shale, dark gray, harder than No. 4; somewhat laminated.... Total thickness.. Interval to base of Lower Coal Measures about 110 feet. FT. IN. 52 There is apparently a local dip here to the west, while toward the south the coal rises for about a quarter of a mile and then descends again. There is also a rise toward the north. The Black Diamond Coal company's shaft is situated about a mile and a half southwest of Bevier, and is connected with the Hannibal & St. Joe railway by a switch. The books of the company furnished the following record: Section XI (No. 1 Section sheet). RECORD OF BLACK DIAMOND SHAFT. 1. Soil, black.... 2. Clay, yellow... 3. Clay, red joint, hard FT. IN. 2 10 4 5 17 38 LOWER COAL MEASURES. 4. Clay, very hard, dark blue. 5. Clay, blue, softer.... Depth Interval to base of Lower Coal Measures about 115 feet. |