Page:Proceedings of the Royal Society of London Vol 1.djvu/423

Rh been elevated to a considerable height, and subsequently denudated by the operation of water, as observed by Dr. Richardson, in his remarks upon the basaltic counties of Antrim and Derry in Ireland.

It is to these tracts of elevated strata, and their abrupt terminations, or faults, in the county of Derby, that the author's observations have been principally directed; and he enumerates a series of four dilferent elevations, in Succession, one within the other, of which the innermost is most elevated. The outermost, or least elevated, extends from Nottingham northward into Yorkshire, as far as the river Wharf, this being the eastern boundary of the tract; while its western boundary extends from near Stone, in Staffordshire, to the neighbourhood of Manchester. On the south it is bounded by a fault, which the author calls the great Derbyshire fault; but its northern extent has not yet been ascertained by actual observation.

The second tract, which is much more elevated than the preceding, is separated from it by a fault, which, from the irregularity of its course, is termed the zigzag fault. The elevation of this second tract, on its southern extremity, is such as to bring the great limestone shale, which underlies all the coal strata, against the red marl at the surface.

The third inner tract is considered by the author as still 400 yards more elevated than the second; so that the fourth or lowest limestone rock is raised into a high hill, with red marl at the foot of it, on the other side of the great Derbyshire fault, which here occasions a de- rangement far exceeding anything that has hitherto been conceived to exist.

Of these tracts the outermost appears to have bnt little inclination to the horizon; but the second and third are inclined to each other, and to the adjacent strata, in a direction from S.W. to N.E., the mutual intersection of the strata, or hinge on which they may be sup- posed to turn, passing from Cromford in a north-westerly direction.

The fourth tract includes Bakewell, and a small district round it, and is surrounded by a fault, which Mr. Farey denominates the Bakewell fault. The westa'n side of this tract is most elevated, as well as that of the third, so as to occasion a great elevation of some strata of toadstone, in situations where their appearance had not before been explained. It is in this district that, in Mr. Farey’s estimation, the lowest strata anywhere observable in Britain appear. He reckons as many as three distinct series of coal measures, separated by thick strata of limestone, and of red marl, similar to that which intervenes between the lias and the uppermost stratum of coal; and the lowest of the coal measures is that of the coal-ﬁeld of Derbyshire, Nottinghamshire, and Yorkshire, lying beneath the yellow limestone rock. Beneath these follows what is called the fourth limestone rock, which extends from Castletou, in Derbyshire, southward to lVeaver-hills, near Wootton and Ramsor in Staﬂbrdshire. This he supposes to be the lowest of all British strata; and to this circumstance ascribes the occurrence of some phenomena, which are said to appear nowhere else.