Edinburgh Geological Society. 567 
Tt is true that there have been immense limestone deposits since the 
earliest Palaeozoic ages. These have been over and over again up- 
heaved into land surfaces, and have doubtless formed cliffs and hills 
just as they now do; and so likewise the constancy of natural causes 
demands our belief that rain-water has always contained its percentage 
of carbonic acid, and has in all ages acted on limestone as it acts 
at present. Consequently, there must always have been the same 
tendency to the formation of underground channels by rivers running 
in limestone areas. Again, these rivers must always have had the 
same liability to floods, and the same power of carrying off and. 
crowding into swallow-holes the sickly and the dying land animals 
that may have existed at the time. Consequently the phenomena of 
bone-caves and bone-fissures must be supposed to have been produced 
in all ages; for in all ages the land animals must have been always 
dying, and always being swallowed in underground passages of 
running water. But, strange to say, this presumption of the Uniformi- 
tarian hypothesis is contradicted by facts. Professor Boyd Dawkins, 
who holds to the inference, and avows his own belief in its certainty, 
admits, nevertheless, that as a curious and singular fact, no such 
packed assemblages of animals have been preserved to us belonging to 
any other geological horizon than the Pleistocene. Yet we know that 
the Eocene and Miocene epochs had each a rich fauna of their own, 
and nothing could be more interesting than to find bone-caverns and 
fissures out of which we could restore the skeletons of these lost 
creatures. The only explanation the Professor gives for this dis- 
crepancy between theory and fact is that all such pre-existing caves 
have been destroyed by denudation; an explanation which does not 
appear to me to be even plausible, considering how protected the 
great majority of such fissures are from all superficial causes of 
obliteration, and what immense sections we have of limestone strata 
of all ages. My own explanation would be, at least as a possible 
supposition, that during the Pleistocene period the continuity of 
physical causation had brought about certain special effects, and that 
among these was some sudden diluvial action, accompanied by and 
perhaps caused by extensive fractures of a pre-existing surface. 
But the bone caves and fissures do not present the only conditions 
under which the aggregation and entombment of the extinct Pleistocene 
mammalia requires explanations not easily reconcilable with the 
Uniformitarian hypothesis. I am glad to see, however, that great 
authorities among the most orthodox geologists are beginning to call 
in agencies which imply catastrophes. Thus Professor Boyd Dawkins 
accounts for the accumulation of the Pleistocene mammalia in the 
deposits now constituting the Dogger Bank, by saying that ‘the 
dead carcases had evidently been collected in the eddies of a river.” 
Here we have the agency of rapid waters invoked for the transport 
of drowned animals, and the eddies of these waters invoked for the 
heaping of them at particular spots. But there are many places, as I 
know well from our western coasts, in which the waters of the sea 
rush precisely as rivers rush, and form eddies precisely as rivers form 
them; and Professor Boyd Dawkins does not seem to me to use an 
argument which will stand examination when he argues in favour of 
