The fossils found in the measures incline naturalists and geologists to place this formation in the Jurassic or oolitic periods; but there is some doubt as to its exact place in the scale of creation. We think there can be no doubt of its late origin; but throughout our labors we have found but little aid as to the identity of coal-beds, or coal measures, from the fossils they present. We do not profess to know enough of fossil botany to depend on our own judgment, and nothing definite enough has yet been developed by the labor of others to be of any certain value at the present time of writing. We hope, however, that the time is not far distant when the geologist will read the pages of nature, as written on the rocks, as cor rectly as we now comprehend the wonderful leaf-like pages those rocks represent in the lithological foldings of the earth's crust.
The only operations of note conducted in the Richmond coal-field before the war were the Midlothian and Clover Hill mines on the South Side, as before mentioned, and the Carbon Hill and Dover mines on the north side. The Dover mines were worked on an exceedingly limited scale, by two or three parties. There were also several very small operations con ducted in several other localities,—on the south bank of the James River, near the Danville Railroad, in the vicinity of Black Heath ; but the amount of coal produced was very limited, and the total amount mined in the Richmond coal-field did not exceed 100,000 tons per annum at the commencement of the war.
We think this amount per annum will cover the entire production of the Richmond mines for the last 50 years, as an average, though we believe 250,000 tons have been mined per annum during a few years. No regular record has been preserved ; but the amount raised between the years 1822 and 1841 amounted to 1,750,000 tons, or 87,500 tons per annum; and we do not think the entire amount raised to be over 5,000,000 tons in the aggregate.
The cost of raising this coal, exclusive of mining improvements, has not been less than $2.50 per ton, and, including its delivery in Richmond, about $3.50 per ton. The prices there, from 1850 to 1860, ranged, for "run of the pit," from $4.50 to $5.00 per ton, and for best household coal, from $6 to $7.
There is only one mine operated by improved machinery, including pumps, but not including the ordinary fixtures for delivering the coal from the mines to the surface. This is the Midlothian mine, where, at a late
day, when nearly all the coal accessible to the pit had been extracted, an im mense and complicated Cornish engine was erected at a great expense,—we think $70,000,—when one of the common " Bull engines," or a good high pressure, costing less than one-third of this amount, would have been more available. We merely mention this to show the want of practical know ledge in mining matters displayed by the miners of that district. All the other mines are drained by the old-fashioned bucket, and the coal raised in small "bogies," or "soaves." The pits are of small diameter, and will not admit of double hoisting-ways with ordinary cars. The Midlothian pit is over 750 feet deep to the sump, or 722 to the coal, which was 36 feet thick when struck.
This is the deepest pit in the coal-field; and including the dip-workings to the basin, 150 feet, by slope, the total depth from the surface is 900 feet.
The Black Heath and Clover Hill pits are from 500 to 700 feet deep, the Carbon Hill from 150 to 450, and the Dover from 100 to 400.
There is one slope at Trent's mines, near Carbon Hill, which is about 1800 feet in length, and 700 feet perpendicular, but which has been abandoned for some time, on account of the difficulties with the air and water.
The mining operations in the Richmond coal-field have been generally of the most primitive character, and may be referred to the early days of the elder Stephenson in England. Instead of improving and progressing, they have gone backwards for the last ten years, and are now less able to mine coal with economy than they were 20 years ago. Most of the pro prietors insist on the bucket being the best and cheapest mode of drainage, and keep on raising water instead of coal. Oui bona f Great and permanent injury has been done to a large portion of this coal-field by the numerous small pits sunk along the outcrops of the coal to the depth of from 100 to 200 From these most of the available upper coal has been excavated to an irregular and uncertain extent, and frequently by dip-slopes from the bottom of these pits to indefinite depths. Those mines have been long abandoned and the excavations filled with water; and, as no records are kept of the direction and extent of those old workings, it becomes dangerous now to approach them from the deeper pits, which, of course, now yield all the available coal.