199 
a Theory of the Earth . 
disposed in stories above each other, and which might 
have served as reservoirs to different seas that afterwards 
might have run off and united themselves in the basons 
of the present seas, 
chap. x. 
Observations to be made on the Strata of the Earth and 
Mountains . 
1. The first question is to determine whether a moun- 
tain or any mass of earth and stone is or is not divided 
by strata.* 
2. What, in regard to the theory of the earth gives im- 
portance to the question, whether a mountain is or is not 
stratified, or composed of strata, is the supposition that 
stratified mountains have been formed by the successive 
deposition of substances before suspended in a fluid, 
while those which exhibit no signs of strata may be sup- 
posed to owe their origin to a simultaneous creation, or 
an accumulation not formed in a fluid, or which, at least, 
had nothing successive or regular, or in which there re- 
main no traces of regularity. 
3. If the mountain or mass exhibits no marks of divi- 
sion, the question of its being stratified or not is super- 
fluous. We shall suppose then that it presents divisions, 
and require to know whether these divisions may be call- 
ed strata . The solution of this question depends upon 
three considerations : viz. The regularity of these divi- 
sions, or their parallelism. Their number : the greater 
the number, the more it excludes the idea of fortuitous 
* The word stratum , originally synonimous with that of bed, expressed the 
situation of a substance extended horizontally, and with an uniform thickness 
on a plain and horizontal base. But the signification of this word has been en- 
larged, and it is now employed to express the situation of substances extended 
with an equal or almost equal thickness on bases which are neither plain nor 
horizontal. Note of the Author. 
Might not the term stratum be reserved for those that are horizontal, and the 
name of banks be given to others ? Tit., 
