Geology of the South-east of Devonshire. 443 



a similar condition of things, yet belong to very distinct periods ; it is used, in the 

 present instance, to designate those deposits which have been found to contain 

 certain mammalian remains. 



All the valleys of South Devon, from the Exe eastward as far as Lyme inclusive, have afforded the 

 tusks, bones and teeth of the elephant and rhinoceros. The deposits which contain these remains, 

 though not stratified, have a very distinct horizontal arrangement, consisting of gravel, with irregular 

 layers of sand, and they afford sections similar to those which estuary or fluviatile accumulations usually 

 present. They occur invariably in low situations, proving that, prior to the occupation of the country 

 by the animals in question, the several valleys were as deep as they now are, that the process of excava- 

 tion had been completed, and that the surface exhibited the same outline as at present. 



This period may be contemporaneous with, or immediately subsequent to, that of the occupation of the 

 ossiferous caves ; and in the latter case it would be synchronous with that inundation which seems to be 

 requisite to account for all the appearances presented by the ossiferous fissures, and which will be 

 presently mentioned. 



Comparing the remains of the large Pachyderms found in caves with those of the gravel beds, the 

 latter appear to have generally belonged to old, full-grown animals, whilst collections from Kent's Cavern 

 show that the animals were mostly young. 



Referable also to this period are those accumulations which, at the western base of Haldon, either fill 

 the wide fissures in the lime rocks, or are collected in depressions on their uneven surfaces ; the latter 

 containing the remains of all the animals found in the fissures, as may be constantly seen at the great quarry 

 near Chudleigh, whenever the workmen remove the "head" to get at the surface of the limestone*. 



^ 2. Ossiferous caves and fissures. — The phsenomena of ossiferous caves, fissures 

 and breccias have been usually classed together, but they appear to me to be really 

 distinct, both as to time and the circumstances which produced them. 



Their natural order appears to be, 1st, the caves which have been inhabited 

 by animals ; as Kent's Hole, Anstis, and Yealmpton, described by Col. Mudgef. 

 2ndly, a complex group, including all those breccias or superficial collections of 

 angular fragments usually found in the neighbourhood of calcareous strata, fre- 

 quently associated with the bones of animals, and which seem also to have required 

 the aid of moving water to have reached their present positions ; and 3rdly, the 

 large fissures in lime-rocks, as those of Chudleigh and Plymouth, now filled to 

 their mouths with ossiferous breccias, but often expanded into chambers containing 

 masses of mud, bones and debris, the forms and positions of the accumulations 

 clearly pointing to the vertical fissure through which they were introduced. Con- 

 firmation of this process of filling is afforded by many limestone caverns which 

 have not been found to contain any remains of animals ; such caves having the 

 character of fissures, and must not be confounded with the inhabited ones. In 

 filling the fissures the transporting power of currents of water is required, which 



* The collection of bones of extinct animals found in a depression in the limestone of the Hoe, and 

 which Dr. Moore brought before the Geological Section of the meeting of the British Association at 

 Plymouth in 1841, were most probably from a similar superficial accumulation. — (Note, 1841.) 



f Geol. Proceedings, vol. ii. p. 399, 1836. 



