1816.] An. Essay on Rents: 123 
part of the earth has been formed. I shall not bring forward all 
the observations necessary in a complete system, but only such as 
are most intimately connected with the proposition under considera- 
tion; and I shall in general, and as much as I can, confine myself 
to new data; observing, in the mean time, that all the old and well 
established facts fall in with these data in such a way as to lead as 
near as possible to a true theory. 
Some geologists arrange all the known matter of the earth under 
the classes primitive and secondary; others make the divisions pri- 
mary and secondary ; and others divide into primitive, transition, and 
floetz. None of these classifications is sufficiently correct. ‘The 
term primitive probably originated from the idea that the matter so. 
called is in its original solid state; and if this word were not appli- 
eable to matter arranged in the other classes, and had no reference, 
in contradistinction, to the term secondary, it would certainly in 
this sense be applied with propriety ; but when, considered with re- 
ference to the word secondary, its aptness is altogether lost ; for 
though secondary matter is not in its original situation, it undoubt- 
edly possesses its first state of solidity. In other respects these. 
terms are improper: the greatest part of primitive matter is unstra- 
tified, but some varieties are stratified, as, for instance, quartzy 
sand-stone, or stratified quartz, compact green-stone, &c. Now as 
primitive matter is both stratified and unstratified, the distinction is 
lost, and the matter of two classes confounded together. These 
objections apply with equal force to that arrangement which divides 
the earth’s matter into the primitive, transition, and floetz classés. 
To these objections may be urged those which follow. All the 
matter belonging to the classes primitive and transition is strictly 
primitive ; therefore if a distinction be made in classing this matter, 
it ought only to be of subordinate consideration. If the term floetz 
literally means stratified, it is sufficiently distinct, provided no 
matter is arranged under it that is not stratified; at any rate, how- 
ever, stratified is by much the better term. But whatever be the 
opinions of geologists as to the earth’s mode of formation, two 
terms, namely, concrete and concrete-stratified, may be used, which 
accord exactly with its structure, and which have very little refer- 
ence to theoretical speculations. 
Of Concrete Matter. 
The concrete matter comprehends the primitive or primary 
matter; and includes all the primitive ; some, if not all, of the tran- 
sition ; and a few of the floetz, and the newest floetz trap forma- 
tions of Werner. This matter may be divided into earth-étone and 
lime-stone. 
1. Of Concrete Earth-stone. 
The earth-stone completely surrounds the inner part of the 
earth. Jt is a concrete. mass that can only be distinguished inte 
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