THE GEOLOGIST. 
which are superior to the till, numerous fossils of species tliat no 
longer exists similarly associated on the neiglibouring coasts/ 
But though this observation of Mr. Smith's may be correct, so 
far as his immediate locality is coDcerned, it is far from being a 
circumstance of so general occurrence as to justify the conclusion 
that the post-tertiary fossils belong to an epoch posterior to the 
erratic boulder formation. On the contrary, in the western 
'parts of Lancashire, marine remains of the following genera, 
namely, Tarritelhj Buccinum, Cardium and Venus; also corals 
of the genera Caryophyllia and Cellepora^ — are frequently met 
with at all depths in the clay deposit, and are in general asso- 
ciated with the transported boulders which have been derived from 
the primitive rocks of Cumberland. Nor is this a merely local 
circumstance ; for Sir Philip Egerton has found a bed of gravel 
containing marine shells of recent species, under the ordinary 
sandy diluvium of Cheshire, which abounds in transported boul- 
ders. Other cases might be cited to show that the shell depo- 
sits are not posterior to the diluvial formation. Phillij)s, to use 
his own words, considers that ^ generally the great masses of di- 
luvium, and the large and far-travelled boulders, which are sup- 
posed to indicate cataclysmal movements, lie upon such shelly 
beds.' 
The circumstance of marine mollusca being contempora- 
neous with the transportation of erratic blocks, militates strongly 
against the theory which supposes the boulders to have been 
polished and transported by the dilation of an immense arctic 
glacier, which, at a certain epoch, covered the greatest portion 
of the British Isles ; for, if such a glacier ever thrust itself into 
the bays which are so common in some parts of Great Britain, 
it is very probable that such fragile things as shells would have 
* These are both recent species — the one being probably the Tvj'binoUa Bo- 
realis of Fleming, and the other the Cellepora pumicosa, both of which exist in 
the British seas. They occur in the clays, and not the sands and gravels, in which 
mountain limestone fossils liavc been found in some other parts of Lancashire. 
