182 
OLDKR PLIOCENE PERIOD. 
[Ch. XIII. 
of England, which may, therefore, have been formed when 
the testacea of the older Pliocene period were in existence. 
Upon the whole, we may imagine the crag strata to bear a 
great resemblance to the formations which may now be in pro- 
gress in the sea between the British and Dutch coasts, — a sea 
for the most part shallow, yet having here and there a depth of 
50 or 60 fathoms, and where strong tides and currents prevail ; 
where shells, also, and zoophytes abound, and where matter 
drifted from wasting cliffs must be thrown down in certain 
receptacles in the form of sand, shingle, and mud. 
In conclusion we may observe that the history of the crag 
requires further elucidation, and the author is by no means 
satisfied with the sketch above given ; but as the country is so 
accessible and the formation so interesting both in its structure 
and zoological characters, it is hoped that these remarks may 
excite curiosity and lead to fuller investigation. 
Sheppey. ■ — « Ramsgate. — Brighton. — Deposits have lately 
been observed by Mr. Crow * resting on the London clay, 
in the Isle of Sheppey, at the height of 140 feet above the sea, 
and by Captain Kater at Pegwell Bay, near Ramsgate, at the 
height of a few yards, and by Mr. Mantell, in the cliffs near 
Brighton, all containing recent marine shells. But as there are 
only five or six species yet discovered in these localities, we 
cannot decide, till we obtain further information, whether these 
strata belong to the crag or to a more recent formation. 
* Of Christ Church College, Cambridge. 
