44 
CHAP. IV. 
TERTIAKY FORMATIONS. 
In the deposits previously described, but little 
order or regularity was perceptible ; their varied 
contents being, for the most part, indiscriminately 
mingled, and bearing incontestable proofs of having 
been produced by the action of water in a state of 
agitation, on the more ancient strata ; but those 
which form the sul^ject of the following sections, 
will be found to present a certain and constant 
order of superposition ; particular fossils will be 
seen to occur in some of the strata, and to be 
wanting in others ; yet, even in these formations, 
traces of extensive diluvial action appear in the 
pebbles, and other water-worn materials, of which 
some of the strata are almost entirely composed. 
Tlie class of deposits to which these belong, 
were but imperfectly known, till the researches of 
MM. Cuvier and Brongniart, in the environs of 
Paris. The publication of their masterly deline- 
ation of the Geographie Mineralogique, of that 
district, excited universal attention, and attached 
to the investigation of these strata a high degree 
of interest and importance. The inquiry was pur- 
sued with equal zeal and success, in our own 
country, by Mr. Webster, who discovered in 
London, Hampshire, and the Isle of Wight, a 
series of beds, corresjionding in their characters, 
and geological position, with those of the neigh- 
