1819.] Memoirs of the Wernerian Society, Vol. 11. Part II. 139 
every difficulty that could be started against their peculiar 
opinions ; but whether it would be attended with advantages 
sufficient to induce us to adopt it, is\a question which deserves 
some consideration. The subordinate formations of Werner were 
a very ingenious thought, and enabled him to generalize the 
structure of the earth much more easily, and to make it much 
more interesting than would have otherwise been possible. He 
was never embarrassed by the appearance of a subordinate 
formation. He had merely to assign the great formations in 
which it was apt to occur. Then it might be indifferently pre- 
sent, or absent, as far as the theory was concerned. The point 
was to establish the great general formations, which included 
the subordinate ones. But if we affirm that there is only one or 
two floetz formations, and that all the other formations that occur 
in floetz districts are subordinate to these two, is not this merely 
another mode of giving up the regularity of the structure of the 
crust of the earth, and tacitly affirming that there is no regularity 
whatever in the order in which the different rocks follow each 
other? If greenstone, porphyry slate, compact felspar, &c. occur 
in old red sandstone, and in the newest floetz trap formations, 
and in all the intermediate formations, and if there be no crite- 
rion by which these rocks can be distinguished from each other 
in these different positions, it seems clear that the occurrence of 
these rocks can give us no information of the part of the series 
in which they occur. We may find greenstone below coal or 
above coal, or in places not in the least connected with coal ; 
so that the occurrence of greenstone can give us no information 
whether the tract of country in which we find it be situated below 
the coal or above the coal. The same remark may be applied 
. to all the other rocks which constitute only subordinate forma- 
tions. I conceive, therefore, that it will be worth Prof. Jameson’s 
while to consider whether the prodigious extent which he is 
inclined to give to subordinate formations be not a virtual 
acknowledgment that the order of the different rocks constitut- 
ing the crust of the earth, is less regular than Werner thought 
itto be. I do not wish him to abandon the doctrine of general 
formations. If it can be shown that there exist no more than 
five general formations ; namely, 
1. Granite. 4, Sandstone. 
2. Gneiss and mica slate. 5. Chalk. 
3. Clay slate. 
And if all the other rocks be subordinate to these, this will be 
at least a very material point ascertained. I think it likely that 
geologists would come sooner to correct results if they were to 
begin by assuming those formations only to be general which 
are observed covering very large tracts of country, and in the 
most opposite parts of the earth. 
Professor Jameson’s account of the red sandstone of Scot- 
