VESPERTINE.
This formation is the lower base of the coal measures. It is the subcar boniferous of the English, and contains the proto-carboniferous or false coal measures. Its features are bold, characteristic, and prominent, and present much uniformity around the Anthracite Coal-Basin, the detached portions of the Alleghany coal-field, and along its eastern escarpment.
The vespertine white sandstone is of great thickness. Its Atlantic out crop is two thousand feet thick, while the supporting "old red" or ponent is nearly a mile in thickness. These immense masses of rocks rise like a framework of mountains around our coal-fields, following them in parallel belts of red and white with artistic and picturesque effect.
Prof. J. P. Lesley, in his little, but valuable and interesting, "Manual of Coal," from which we have borrowed many useful facts, thus speaks of those red and white sandstones as the floor or base of our coal-fields:— " The THIRD GREAT SANDSTONE of the floor, No. X., is not so remark able for introducing a new era of fossil life, as for inaugurating a new system of groups of mountains along its frequent outcropping, which keeps them always and everywhere apart from the groups of No. IV. (Levant), never approaching them within three miles, and usually running in parallel lines with them at a variable distance of from ten to twenty miles, the intervals being always filled up with the narrow knobs of the Oriskany, No. VII., and the broad, high, undulating, deeply-ravined, and always cultivated hills of No. VIII.
"On the out or lower side of all these mountains of X., runs an uneven terrace of the red sand of IX.; and in those regions where the rocks stand vertical, this terrace rises to a separate summit of equal height with the true summit, and beautifully parallel with it; a narrow, shallow crease divides the double summit, and then the long, straight mountains, with twin crests of wonderful evenness, but with this difference, that the outside one is red and the inside one is white, runs along the map like the double beading of a picture-frame. This is true of all that southeastern outcrop which encircles the Anthracite Coal-Basins, folding scrupulously in and out around their long sharp points, crossing and recrossing the rivers and creeks, and presenting always outwardly, or from the coal, its terrace of old red sandstone. The same red and white frame is repeated around the
Broad Top Coal-Basin, south of the Juniata.
"The Terrace Mountain is its northern point and western side, and Side long Hill is its eastern. The same surrounds the Cumberland Coal Region. This is the formation which constitutes so many of the long, straight parallel ridges of Central and. Southwestern Virginia. Like the Medina sandstone last described, it is of immense thickness in the east and thins rapidly towards the west. Its Atlantic outcrop is over two thousand feet thick, hard and white, while its supporting red rocks, No. IX., are at least a mile in thickness. Only the upper part of this red mass, however, forms the terrace or supplementary crest, except when they all lie nearly horizontal. This is the case with the Catskill. Here the vast piles ascend in steps a height of three thousand feet, IX. upon VIII. and X. upon IX., and on top of all the lower layers of XI. But as we follow this easternmost outcrop south through Virginia into Tennessee, it slowly thins, as if the original direction of the sediment was from the north and east. Yet more striking is the case when we pass over to its inner outcrops. Around the Broad Top, and where it passes down beneath the Great Savage, it is still a mountain mass, but it rises again in Ohio and Northern Pennsylvania from its underground journey so lean and changed as scarcely to be recognized. It is there a greenish sandstone less than two hundred feet thick. The whole intermediate space, of course, it underlies; that is, all Northern and Western Pennsylvania, all Western Virginia, and the whole southern region of the Cumberland Mountain. Here it is as thin as in the Catskill region, but here, as there, helps to pile up the immense plateau which, narrowing as we go southward, d.omincers .
with its lofty terminal crags the plains of Alabama."