56 Rev. A. Sedgwick on the Geological Relations and 



glomerate^, or of any other bed indicating an extraordinary mechanical action) 

 it rests on the coal-measures, and seems to partake of their dip and inclina- 

 tion. It is, therefore, only after an extensive comparison of the two formations 

 that we can make out their general want of conformity. The fact appears 

 however, in the first place, to be proved by the continuity and extent of the 

 magnesian limestone, which, after ranging over the rich carboniferous deposits 

 of Nottinghamshire, Derbyshire, and Yorkshire, comes in contact with the 

 unproductive region of the millstone-grit; then crosses the Tees, skirts the 

 West-Auckland basin, and afterwards crosses a productive part of the great 

 Durham coal-field. In this range it passes over the edges of a succession of 

 deposits which are neither continuous nor contemporaneous ; it must there- 

 fore necessarily be unconformable to all of them. As these relations are of 

 great economical importance, and have been in some respects misrepresented, 

 the details connected with their history ought not to be passed over without a 

 short notice. 



i. The magnesian limestone is first seen near Nottingham in the form of thin and nearly hori- 

 zontal beds occupying the level tract of country to the north-west of Radford. On the contrary, 

 the coal-measures form an uneven hilly region stretching on the south-west side of the limestone. 

 This contour tends to prove that the upper formation is unconformable to the lower ; and the in- 

 ference is said to be confirmed by the existence of some dislocations which traverse the coal strata 

 without affecting the limestone. That the magnesian limestone in this region forms but a thin 

 capping on the inferior strata, is demonstrated by the sections exhibited in a great many coal-pits 

 which have been sunk through it. Many of them are now worked out and deserted ; but some 

 of them are still carried on near Radford and Asply *. 



2. The regular range of the coal beds under the magnesian limestone is further demonstrated 

 by a shaft near the edge of the escarpment at Kimberley, which passes through thirteen yards of 

 the limestone, and then descends thirty-eight yards to a three. foot bed of coal. 



3. The same conclusion is confirmed by the position of the Kirkby coal-works, and by the 

 general dip of the strata in that part of the Nottinghamshire field. South of the village a deep 

 valley of denudation encroaches on the boundary of the magnesian limestone ; and in the lower 

 part of the valley a new shaft has been sunk not far from the limestone escarpment, to the depth 

 of more than 180 yards. The coal-measures are found to dip nearly due east at a small angle ; 

 and an excavation, formed for a rail-way, has exposed the junction of the upper beds of the series 

 with the magnesian terrace, under which they appear to range with an uninterrupted and uniform 



* I have been informed that a pit which was worked in the year 1823 near Asply, first passed 

 through four or five yards of magnesian limestone, and then descended to the five-foot coal through 

 seventy-six yards of the regular coal-measures. On the western side of the same coal-field near 

 Bilborough, the measures are said to have been thicker. The old works were sunk through 

 a few yards of limestone, descended thirty yards (through shale and bind) to a twenty-seven- 

 inch bed of soft coal, and were afterwards carried down ninety yards to the five-foot coal. 

 At all events, the sections near Nottingham prove that the coal beds pass under the limestone 

 without any diminution in their value, except what arises from the greater difficulty of reaching 

 Ihem. 



