X PERMIAN FOSSILS. 
varied suite of fossils than was known to occur in the contemporaneous rocks of England, 
or Germany,—their having no proper distinctive general title, except such as were 
obviously inappropriate,—and in consideration of the general reception and fitness of 
geographical names for co-ordinate groups, as exemplified by those previously im use, 
—Sir R. Murchison was induced to apply to these deposits the term Permian, which, 
it will be perceived, is derived from the name of the country in which they are most 
extensively developed. 
The Permian system, as developed in the North of England, is divisible into six 
distinct members, having the following order of superposition. 
a. Crystalline, earthy, compact, and oolitic limestones. 
6. Brecciated, and pseudo-brecciated limestones. 
c. Fossiliferous limestone. 
d. Compact limestone. 
e. Marl-slate. 
j. Various coloured sandstones. 
By traversing certain districts in the County of Durham, the above order of, 
position will be observed. Thus, passing from the edge of the limestone near ~ 
Bolden direct to the coast, we meet with, at the base of the Cliff on the west 
side of Down Hill, a bed of freestone,—the lowest member of the series (/); next 
the overlying Marl-slate (e), on which repose several beds of brown-coloured lime- 
stone (/), the lowest of which are flaggy, and the highest gritty and imperfectly 
concretionary. Following the direction of the dip of these deposits, that is, towards 
the coast, we first meet with beds of light-coloured limestone (c), containing numerous 
organic remains, as at Hylton-North-Farm, and Southwick-Lane-House: this is 
succeeded in the ascending order, as in the West Quarry at Southwick, by a variety 
of beds generally of a brecciated and pseudo-brecciated character (0); and these in 
their turn become overlaid by vast beds of crystalline and other limestones (a), 
extensively worked in the Fulwell Quarries, and continued down to Roker Cliffs on 
the coast, where they are lost in the German Ocean. It often happens that this order 
of superposition is obscured by some of the beds becoming modified in character, or 
some of the members being absent. ‘The inferior limestone (d) is, in some places, 
compact, and of a uniform dark gray colour (Midderidge) ; in other places it is deep 
brown, imperfectly concretionary, thin bedded, and sometimes cellular (Harton, &c.) ; 
and ina few others mottled, and ribboned with various shades of brown and gray 
(Pallion): it also varies in chemical composition, consisting in general simply of 
carbonate of lime, to which is added, in a few localities, (Ferry-Hill, Johnston,) a 
considerable portion of carbonate of magnesia. The highest member of the series 
(a) is another deposit, varying even more decidedly im its characters : a bed at one place 
may be crystalline, compact, and ash-coloured; and at a few yards distance, earthy, 
