FOURFOLD DIVISION. 77 
tertiary strata, in their inestimable history of the 
deposits above the chalk near Paris. For a 
short time, these were supposed to be peculiar 
to that neighbourhood ; further observation has 
discovered them to be parts of a great series of 
general formations, extending largely over the 
whole world, and affording evidences of, at least, 
four distinct periods, in their order of succession, 
indicated by changes in the nature of the or- 
ganic remains that are imbedded in them.* 
Throughout all these periods, there seems to 
have been a continually increasing provision for 
the diffusion of animal life, and we have certain 
evidence of the character and numbers of the 
* We owe to Mr. Webster, the first discovery of the Tertiary 
strata in the I. of Wight, and S. E. Part of England. (See Geol. 
Trans. Lond. O. S. Vol. 2. p. 161.) 
Mr. Lyell, in Vol. II. of his Principles of Geology, has given an 
interesting map, showing the extent of Europe, which has been 
covered by water since the commencement of the Tertiary strata. 
M. Boue, also, has published an instructive map, representing 
the manner in which central Europe was once divided into a 
series of separate basins, each maintaining, for a long time, the 
condition of a fresh-water lake ; those which were subject to oc- 
casional irruptions of the sea, would, for a while, admit of the 
deposition of marine remains ; the subsequent exclusion of the 
sea, and return to the condition of a fresh-water lake, would allow 
the same region to become the receptacle of the exuvise of ani- 
mals inhabiting fresh water. — Synoptische Darstellung der Erd- 
rinde. Hanau, 1827. The same map, on a larger scale, appears 
in the 2nd series of the Trans, of the Linn. Soc. of Normandy. 
In the Annals of Philosophy, 1823, the Rev. W. D. Conybeare 
published an admirable memoir, illustrative of a similar geolo- 
gical map of Europe. 
