42 
general, vast beds of gravel appear, composed of pebbles ; varying 
much in their size and form : and with this is also commoidy found 
the fine gravel ; which likewise varies, in different parts, in its 
degree of fineness, and in its colour. Underneath these, in many 
parts, are the infinitely varying strata of sand-stone, lime-stone, &c. 
which serve to supply materials for various articles useful in social life. 
They also serve, with the sand and gravel of the third stratum, to 
supply that kind of surface to the earth, which may best expedite the 
intercourse, which must, necessarily, take place between the inha- 
bitants of distant parts. These strata of stone, varying perpetually in 
their colour, solidity, and texture, form, in some places, the ceilings 
and floors of the vast subterranean caverns, which are found in 
various parts of the world ; and which often contain, as do those, 
particularly, in the principality of Bayreuth, and in the Hercynian 
forests, very interesting specimens of those remains, which are the 
objects of our particular research. They also form the surrounding 
parts of those mines, which contain the valuable metals, which 
civilized man forms into innumerable articles of utility, and of orna- 
ment. Beneath schistose or slaty strata, are generally found the 
immense beds of coal, so necessary to the comfort, and in some 
situations, even to the existence of man. 
In almost all these strata, even to a very considerable depth, the 
remains of vegetables and animals, which have existed in former 
remote periods, are frequently found ; and, in general, possess the 
same physical and chemical properties with the strata themselves. 
What these constituent parts are, becomes, therefore, an object of 
necessary examination. 
Of the first stratum of mould, sufficient has been already said for 
our present purpose. 
Clay, which I have reckoned the second stratum, has for its basis, 
the earth called alumine, or 4he earth of clay, which constitutes 
