MUSEUM OF THE NATUEAL HISTOET SOCIETY. 253 



Millstone Grit.— Flagstones and shales, -with coarse grits full of quartz 

 pebbles and a few thin seams of coal. 



Yoredah series.— Thick or thin beds of Mountain-limestone, with thick 

 beds of shale and fine or coarse sandstone, sometimes highly crystalline. 



Scar -limestone or Carbonaceous series. — Beds of thick limestone in the 

 south, with beds of crystalline sandstone (Hazle) and shale (Plate). In 

 Northumberland the beds of limestone become thin and subordinate, as 

 they extend North, to thick beds of grit, sandstone, and shale. 



Calciferous sandstone or Tuedian.— Numerous beds of grey, greenish, 

 and lilac shales, sandstones, slaty and calcareous sandstones, thin beds of 

 argillaceous limestone and chert, and a few buff-coloured beds of mag- 

 nesian limestones. — George Tate. 



Coal Measuees. — This properly includes all the strata from 

 the "base of the Marl slate to the lowest seam of workable coal, 

 called in this district the Brockwell. It consists of numerous 

 beds of fine or coarse-grained sandstone (post) and occasional 

 beds of grit with quartz pebbles, of variable thickness, inter- 

 stratified with beds of arenaceous, micaceous, or pure shale 

 (metal). Among these, and most thickly developed in the lower 

 part of the series, though by no means confined to that portion, 

 are the valuable workable seams of coal. These seams of coal 

 vary greatly in thickness and quality, and as they split or are 

 divided occasionally into two seams, and receive different names 

 in different districts, their identification is sometimes difficult, 

 and has not hitherto been perfectly accomplished. This desirable 

 result could however be successfully attained by running close 

 traverses across the coal-field from east to west, the numerous 

 collieries working in the district and the registered sections of 

 many others affording excellent and reliable material for such a 

 purpose. For easy reference to the principal coal-seams the late 

 Mr. Buddie's excellent " Synopsis of the Seams in the Newcastle 

 District" is appended.* 



The majority of the specimens in the Museum Collection were 

 obtained from the Boof-shale of the Ben sham-seam at the Old 

 Jarrow Coal-pit and from the Boof-shale of the Low-Main-seam 

 at the Felling Colliery. 



* Nat. Hist. Soc. Trans, vol. i. p. 215. 



