413 
call the substance on which they are formed hlack-haft : the colliers 
about Newcastle and Durham call it plate. The stratum of this is 
about a yard thick, lying 120 feet deep, and 30 feet above the 
Cannel-coal. One specimen he describes as a black slaty coal, 
marked in a quincunx manner, &c. much like what might have 
proceeded from the bark of common fir. Another he describes as 
having the appearance of long striated leaves, having the appear- 
ance of joints, &c. upon a dark grey slaty stone. The stratum of 
this, he says, lay at the depth of 25 fathoms, in Branstycliff, by the 
Duke of Somerset’s salt-pans, near Whitehaven. The stratum, he 
says, was about a foot and a half thick ; and upon the breaking of 
the stone, leaves of plants appeared very thick in all parts of it, 
where the grain of the stone was thus fine and dense. But where it 
happened to be more gritty, coarse, and lax, there was not one leaf 
to be met with*. Specimens of schisti thus bearing impressions of 
vegetables are displayed Plate I. Fig. 6 and 7 ; Plate IV. Fig. 6 and 
7 ; and Plate V. Fig. 1, 2, 3, 6, 7 , 8, 9- 
The impressions of leaves are much more rarely discovered in the 
sand-stone strata, and are traced with much more difficulty ; owing 
in part to the uncertain direction in which these stones often split ; 
and, in part, to the leaves being twisted, and to their laying in a 
confused and irregular direction : hence the leaf is generally divided 
with the stone, and its edge, or section, only exposed. Sometimes, 
however, a very fair impression of a leaf may be seen, on sand- 
stone ; but it will be found, in general, to differ very much in some 
respects from the impressions on the argillaceous schists. Plate V. 
Fig. 4, and Plate III. Fig. 3, 4, and 5, represent the impression of 
vegetables on different kinds of sand-stone. 
The occurrence of vegetable remains in lime-stone strata is un- 
doubtedly much more rare than in the argillaceous, or schisti. 
* Catalogue of English Fossils in the Collection of J. Woodward, M.D. Part II. p. 16. 
