mt 
a Theory of the Earth « 
10. It is of importance to observe, in inclined or verth 
cal strata, whether their thickness is not greater at their 
basis than at their summit. 
11. To observe the joinings of the strata, and whe- 
ther any substance different from that of the strata is 
placed between them, and what is the nature and thick- 
ness of this substance. 
12. To observe whether the contiguous or correspond- 
ing joinings of these strata are smooth or unequal $ whe- 
ther there are observed in them any knots that exhibit 
traces of crystallization or undulations proceeding in a 
certain direction. 
13. In mountains consisting of strata different in their 
nature, or of different thickness, to observe whether their 
return is periodical, so that the same order recommences 
after a certain number or determined interval. 
14. Whether, at the bottom of a mountain consisting 
of horizontal strata, there are not found mountains com- 
posed of vertical strata resting against the basis of that 
mountain. 
15. In bent or circular strata, to observe in the elbows 
or points where the flexion is greatest, whether the strata 
are or are not broken. 
16. When the strata have the form of a C, to observe 
whether at the back of the C there is not a vacuity*, 
which proves that the upper part has been thrown abov6 
the under part. 
17. To examine, in general, w hether the strata exhi- 
bit traces of violent convulsions, which may have changed 
their primitive situation ; or, on the contrary, whether 
the whole, as well as the straightening of the strata, may 
be explained by simple sinking down. - ' 
* 18. To observe, whether, on approaching the high primitive mountains, the 
calcareous strata do not seem to have been reversed in a more violent man* 
aer. B. 
Vol, I. 0 e 
