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embedded in river deposits or caverns in the limestone dis- 
tricts, which, in many cases, owe their formation to the action 
of underground currents of water from streams or the accumu- 
lation of springs, while the majority gf caverns owe their con- 
tents to the falling of animals into open fissures and the trans- 
porting power of water: others, again, have been inhabited 
for ages by wild animals, and filled with the remains of their 
prey. The fissures, or old swallet holes, are in many instances 
still open, and more or less erect; and farmers will tell you 
that they have lost sheep, horses, oxen, and dogs, that had 
no means of regaining the surface. In caverns, however, 
which have afforded shelter from the weather, man and wild 
animals have resorted from the Pleistocene times to the 
present day; hence in such localities remains of different 
epochs are found. As in Kent’s hole, for instance, where, 
overlying the mass of bones dragged in by hyaenas in 
Pleistocene times, and sealed down by stalagmite, a layer 
of dark-coloured earth, containing various implements of 
bone, flint, and pottery, and exhibiting upon its surface the 
indications of the feasts and fires of some early race of 
people. The Kirkdale cave, in this county, contained several 
Pleistocene mammals intermixed with those of our own day. 
The Paviland cave, again, exhibited a mixture of Pleistocene 
and Prehistoric remains; while, in other instances* those of 
Prehistoric age only are met with. The old river gravels, 
loams, and brickearths, which are sometimes very high above 
the level of the nearest stream, are the result of the erosion 
of the rocks during the formation of the valleys by the 
ancient rivers flowing at a far higher level than at present, 
which has cut down their beds to the present level, so that 
the remains from the caverns and the river deposits are, 
geologically speaking, of the same date. Some of these 
deposits are of vast antiquity, and contain the remains of 
the extinct mammals that inhabited Yorkshire, and happened 
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