on Kent's cavern, Devonshire. 19 



and not unfrequently loam, stones, and splinters of bones are cemented by 

 the same substance into a very tough breccia. The presence of a calcareous 

 drip is more or less traceable everywhere. Hitherto the cave-earth has been 

 excavated to the depth of 4 feet only. How far it extends below this, or 

 what may be beneath it, is at present unknown. Where it is not covered 

 with the stalagmitic breccia, the black soil lies immediately on it ; but the 

 line of junction is everywhere sharply defined. In no instance do the two 

 commingle. 



Since the large masses of limestone occur at all levels in the cave-earth as 

 well as everywhere above it, it is obvious that whatever may be the cause to 

 which their fall is attributable, they cannot be referred to any one and the 

 same period. They fell from time to time throughout the accumulation of 

 the cave-earth, they continued to fall whilst the stalagmitic breccia was in 

 process of formation, as well as during the introduction of the black mould, 

 and they are amongst the most recent phenomena which the cavern presents. 

 And even of those which lie on the surface, there is conclusive evidence that 

 in some cases a considerable interval of time must have elapsed between the 

 fall of two blocks lying one on the other — an interval sufficiently great for 

 the formation of the cake of stalagmite between them, and which is some- 

 times fully 6 inches thick. There can be little doubt that some of them 

 fell very recently, even when measured by human standards. 



It is by no means easy to determine the cause which threw them down. 

 To call in the aid of convulsion seems undesirable, since it would be necessary 

 to do so very frequently. Moreover, it may be doubted whether anything 

 short of a violent earthquake would be equal to the effect. Though the roof 

 of the chamber is of very great span and entirely unsupported, and though 

 it presents appearances which are not calculated to inspire confidence, the 

 violent concussions produced by the frequent blastings already mentioned, 

 blastings which not unfrequently throw masses of limestone, weighing up- 

 wards of a ton, to a distance of several feet, have never brought down even a 

 splinter. 



The fall of the blocks has sometimes been attributed to changes of dimen- 

 sions in the roof arising from changes of temperature ; but the fact that the 

 cavern temperature is all but constant throughout the year, seems fatal to 

 this hypothesis. 



The masses lying on the surface were a sufficient guarantee that the de- 

 posits beneath them remained intact. There can be no doubt that they are 

 at once a proof and the cause of the undisturbed character of the soil they 

 cover. A portion of the cavern so easily accessible as is this chamber, 

 would not have been spared by Mr. M'Enery, but on account of some great 

 difficulty or discouragement ; and in fact he states that the fallen masses 

 completely foiled him in his attempts to make explorations in it, excepting 

 in one branch some distance south of the area selected by the Committee. 

 Their own characters, moreover, render it absolutely certain" that the deposits 

 have never been violated. 



The following is the method of exploration which has been observed from 

 the commencement, and which it is believed affords a simple and correct 

 method of determining the exact position of every object which has been 

 found. 



1st. The black soil accessible between the masses of limestone on the sur- 

 face was carefully examined and removed. 



2nd. The limestone blocks occupying the surface of the deposits were 

 blasted and otherwise broken up, and taken out of the cavern. 



c2 



