442 
THE GEOT,OGIST. 
lictwcen tliis mass of lictcrogcnous niiitcriiib and the western- or what may 
l)c callfd tlic river-wall of the cavern there oceiirred a nearly vertical brecciated 
jilate, or dyke, which the workmen denominated "callis," extremely tough, and 
quite as diirieult to work as the compact limestone itself. The only means of 
severhig it was by blasting; and being considerably less compact than the 
liniestouc, the expansion of tiic ignited ])owdcr told on it with much less 
eileet. It may be described as an approximately vertical plate of stalactitic car- 
bonate of lime, containing, at by no means very wide intervals, nuisses of 
breccia made up of the materials just named as composing the accumulation 
in contact with and on its eastern or liill-side, and cemented together by car- 
bonate of lime. Some of these masses measured fully a yard cube, but the 
general thickness of the "callis" was about two feet. This was tlie bone- 
bed, that is to say, the bones were found alike in the " callis," and in the 
mass of heterogenous materisds beside it, in the cemented and uneemented 
portions of the bed. They were found alike at all heights or levels, in tlie 
lumps of breccia, in the pure stalagmite between them, and in the looser and 
less coherent portion of the accumulation, thereby suggesting that the cavern 
wii.s slowly and gradually filled with limestone-debris detached from the rock 
in whicli the cavern occurs, with sand transported at least from some distance, 
and with mud, not each in definitely successive periods but together, with 
occasional pauses, or periods of cessation ; the proof of such pauses being the 
frequent presence of the portions of pure stalagmite separating series of 
brecciated masses made up of angular limestone, clay, and sand, lyijig one 
above another in the same nearly vertical plane. The rapidity of the iullUing, 
and hence tiic time required for the process, seem of necessity to be measured 
by the rate of deposition of the stalagmite, wliatever tliat may have been. It 
appears, too, that throughout the entire period — be it long or short — required 
for and represented by the accunmlation of the materials now under considera- 
tion — alike duruig the periods of active, and of tardy aceumidation — bones of 
various animals were introduced and iidnimed, and that there was no marked 
cessation in this part of the work, since the bones were found as frequently in the 
pure stalagmite as elsewhere. In that portion of the series whicli is destined for 
the University Museum, at Oxford, a mass of this stalagmite wlU be found 
coiitauiing a fine jaw with teeth, beautifully white and entirely free from any 
trace of soU. The bones are frequently in a very fragmentary condition, many 
of them being mere splinters, as if broken by fragments of rock faUmg on them ; 
tliis, however, may be partly due to the rough handling of the workuien in ex- 
tracting them. 
"I always know," said the old quan-ymau before alluded to, "when we are 
coming to bones where there's clay, for the clay is always fat-Uke. I suppose 
'tis the fat of the beasts that tiie bones belonged to." Evidently he was not 
enough of a philosopher to explain phenomena by caUing to his aid the 
" plastic," or the "sportive powers of Nature;" and probably he was so be- 
nighted as never to have heard of the discovery of " prochroiiism." 
A somewhat considerable number of clay-balls, generally ellipsoidal, and 
varying from an inch and a-half to two and a-lialf inches in greatest diameter, 
were found in tiic clay throughout tlie bone-bed, but not above nor below it. 
Beneath the mass of materials just described, occurs a bed of dark, very 
tough, unctuous clay ; knovMi to be twelve feet thick, but perhaps more, as 
its base has not been readied. It seems to be of the same character as that 
mentioned by Mr. Whidliey in his description of the third cavern, already quoted. 
Oceasioiially it contains a few very small angvdar stones, but with this excep- 
tion it is perfectly houiogeiious. No traces of fossils have been found in it. 
It now remains to consider how the contents of the cavern were introduced. 
The workmen most positively assert that it never was an open fissure ; that the 
