76 EIGHTH REPORT — 1838. 



Hill, Team, Urpeth, Stanley, South Moor, and Lanchester Common 

 Collieries, probably to the outcrop of the coal in that direction. 



" This band first shows itself as a mere parting in the coal ; gene- 

 rally at about 10 inches above the Black-band, which is incidental to 

 the seam. By almost imperceptible degrees it goes on increasing till 

 it reaches the thickness of 3 inches, and becomes a confirmed slate 

 band of a dark gray colour. A little before it attains this thickness, a 

 three-inch layer of coarse ' brassy coal,' (coal mixed with iron pyrites), 

 appears at the bottom of the under division of the seam, separating it 

 from the bottom coal; and it is worthy of remark, that this layer of 

 ' brassy' coal almost invariably accompanies the Heworth Band. From 

 3 inches in thickness the band goes on thickening more rapidly to 12 

 inches, after which it goes on in a still more rapid ratio to 10 and 12 

 feet ; finally dividing and destroying the seam as it goes southward." 



" When the band approaches the thickness of 12 inches, it changes 

 to a much lighter hue, and increases in hardness ; and as it goes on 

 thickening it becomes arenaceous, and finally passes into a stratum of 

 sandstone, 7 fathoms thick, in one of the pits of Washington Colliery, 

 while in another of the pits of the same colliery, it forms a variety of 

 beds of sandstone and gray and black metal stone." 



Considering the extent of the Newcastle coal-field, but few whin 

 dykes occur, as only three or four of any considerable magnitude have 

 yet been discovered. These are the Coaly Plill, the Hamsterly Com- 

 mon or Hett Dyke, the Cockfield Fell Dyke, and the Acklington Dyke. 

 The first of these dykes is the subject of a notice of Mr. Buddie in the 

 Transactions of the Natural History Society of Northumberland, Dur- 

 ham, and Newcastle on Tyne, (vol. i.,) and it is remarkable for its 

 undulatory character and its limited vertical depth. In fact, levels 

 have been driven across the presumed plane of its fissure, both above 

 and below the really existing vertical mass of whin-rock ; of this Mr. 

 Buddie furnishes ample proof from colliery workings, which also dis- 

 close the curious vertical divisions which exist in the dyke. 



The dislocations of the strata called ' slip dykes,' or ' faults,' are 

 infinitely more numerous than whin dykes in the great coal-fields of 

 the Tyne and Wear, All the principal faults and whin dykes were 

 represented by Mi\ Buddie on a map, and minutely described in the 

 paper from documents of the most undoubted accuracy. Accurate 

 sections illustrating these phenomena, were drawn on a magnificent 

 scale, and have been copiecl in a reduced form for publication along 

 with the original memoir, which is expected to appear in the Newcastle 

 Transactions, already rich in contributions to the geology of the coal 

 formation of the Tyne and Wear, from the stores gathered in Mr. Bud- 

 die's extensive mining experience. 



On the Beriuick and North Durham Coal Fields, 

 By D. Mii.NE, F.R.S.E. 



The strata of the BerAvick and North Durham coal field consist of 



