MINERALS AND GEOLOGY OF CANADA. 453 
history. All the succeeding periods have left us, in the rocks then 
under process of formation, vestiges, at least, of their organic types— 
those of each period differing more or less entirely from the forms 
which occur in both underlying and overlying strata. These facts 
are brought out more fully in the succeeding part of this Essay, in 
which the leading questions connected with the subject of Organic 
Remains, come under review. For present purposes, it will be suf- 
ficient to observe that by the careful study and comparison of these 
remains, geologists have subdivided the rock-groups into a certain 
number of formations, indicating the bygone ages and periods of the 
Earth’s history. Without entering at present into minute or contro- 
verted subdivisions, we may group these various formations as in the 
annexed tabular view : 
Modern Formations. 
Drift Deposits. 
Carnozoic or Tertiary Rocks. 
MeEsozoic Cretaceous Series. 
or ; 3 
Sadan AT Jurassic Series. 
Rocks. Triassic Series. 
Permian Series. 
Carboniferous Series. 
PaL#£Z0ZOIC : : 
R Devonian Series. 
oe (For Canadian Sub-divisons, see Parr V.) 
Silurian Series. 
(For Canadian Sub-divisions, see Part V.) 
Azorc Huronian Series. 
Laurentian Series. 
Notes on the above Table. 
(1) The formations enumerated in this table, are never found 
altogether: that is to say, they never exhibit a complete series at any 
one locality. But they are known to occur in this order, by a com- 
parison of their relative positions at different places, Thus, in one 
district, we find (in ascending order) the Silurian and Devonian se- 
ries; in another, the Devonian and Carboniferous, and so on. 
