GRAUWACKE SLATE. 39 
shewn in our neighbourhood, though, as to the exact 
cause of this, as well as of the reflections above 
specified, I can offer no satisfactory notion further 
than I have elsewhere mentioned. 
Greywacke-slate assumes a very different appear- 
ance from all others. It is harder, and not so ex- 
tensively tabular, is of a dark lead colour, and passes 
very freely and very suddenly into greywacke at 
numerous points. Viewing it as it appears on the 
coasts, it displays itself in large flat cakes having 
thin and rounded edges, between which, other cakes 
are in their turns inserted. In the greywacké slate, . 
are found the turbinolias -elsewhere alluded to. 
Beneath the water, these are dislodged by the action 
of that element from their bed, and thrown up in 
more or less perfection of form on the beach, a fact 
corroborative of the general rule, of fossils exceeding 
in density the matrices in which they occur. Dr. 
Leach reports that at Buckfastleigh in this county, 
the lime is seen covering the indurated slate, and 
that, they both at this spot contain a quantity of 
flinty matter. Now, it is singular, that close to the 
place where I reside, there is seen a small quantity 
of lime overlaid by the slate, and both containing 
flinty matter !*—a fact, seemingly confirming, 
amongst others to be named, the contemporaneous 
deposition of these strata, or at least their close re- 
lationship with respect to the convulsions which 
have disturbed the crust of our globe. The circum- 
stance, of strata at their points of junction being more 
*It is very worthy of remark, that flint is by no means limited 
to what is termed the “ cretaceous epoch,” but was prone to form 
even at the early period of slate and limestone deposits. Mr. Bart- 
lett noticed at Berry Head, masses of flint imbedded in the latter 
rock, and some lying on its surface, having been separated by the 
action of the atmosphere. Are their origins due to the remains of 
animals ? 
