At the coal mines of the lias formation, on both sides of the James river, and near Richmond, Va., beds of natural coke of good workable quality are met with, interstratified with the slates, sandstones, fire clay, and coal. On the N. side of the river is a bed 5 ft. thick, which lies slightly inclined toward the west. Several vertical shafts cut it, the deepest about 207 ft. below the surface. The coke is of a nearly uniform character, and is heavier than common coke, vesicular in texture, and of a dull black color. The volatile ingredients of the coal are almost wholly wanting, and the coke does not differ in its properties and appearance from much of the more compact artificial varieties. Twenty feet above the coke, the agent which effected this change, and also altered the beds of fire clay and slate, is seen in an intercalated layer of trap rock of 15 to 30 ft. in thickness. Immediately beneath the trap is a bed of carbonaceous fire clay and cinder 5 ft. thick, baked and hardened by the action of the trap. Under the coke bed is another stratum of indurated fire clay, and beneath this one of coal slates 20 ft. thick. Another carbonaceous bed is then cut by the shaft; this is a thin layer of half-coked coal.
Twenty feet below this is another coal bed of the usual bituminous composition, its structure unaltered.