a Theory of the Earth . 
8* Thus we often see strata of free-stone or pudding- 
stone interposed between the primitive and secondary 
mountains; breches are seen to form the most elevated 
stratum, and consequently the newest of some calcare- 
ous mountains. We must study then the nature,, dimen- 
sions and position of these remarkable strata. 
4. Having found these transitions, or any others, in 
some mountains, if they are not then found in other moun- 
tains, you must examine whether their absence does not 
arise from their having been destroyed ; vestiges of them 
are to be sought for ; and if it appears that they never 
existed, you must endeavour to discover, in the nature 
and position of the mountains, what may have been the 
cause of their absence 
CHAP. XVIIe 
Observations to be made on the Remains and Vestiges of 
organized Bodies found in the Earth , in Mountains*, 
and at their Surface . 
4 . Their nature, bulk, and quantity ; the extent, depth., 
and other dimensions of the strata where they are foundf „ 
2. Their preservation. Whether entire or broken, de- 
composed or not ; shells with their pearly covering 
(nacre ) ; their colour ; remains or traces of their fish, or 
their skin if there be any. To deduce, if possible, from 
these data, some idea of the time that has elapsed since 
these organised beings were deposited in the bosom or at 
the surface of the earth. 
* The best method of observing mountains, in order to acquire a thorough 
| knowledge of them, is, not to confine oneself merely to follow the valleys, but to 
intersect also, as much as possible, the principal chains and the branches detach- 
ed from thepiin the direction oftneir breadth. Til. 
f i. A. If formed of trees, to mark down the direction of the strata; and 
whether they are placed horizontally, or inclined either towards the^ summit or 
the roots. Til. 
VOL. I. X, 1 
