THE BONE CAVES OF THE PLYMOUTH DISTRICT. 
89 
midway in the face of the cliff. These reveal the existence in 
former days of a considerable subterranean waterflow ; and, as a 
natural drainage level, show that during their formation there was 
little change in the relative positions of land and sea — marking the 
point where the waters percolated to their outlet in the open 
channel. A distinction has been drawn between fissure and tunnel 
caverns, convenient for descriptive purposes, but non-essential. A 
tunnel cavern eroded until the roof gives way becomes a fissure 
cavern ; while should the fissure be closed by breccia cemented by 
stalagmite, the tunnel phenomena would be reproduced. Every 
cavern — fissure and tunnel — must during its formation have pos- 
sessed some surface communication, though the opening may have 
been subsequently closed. 
Interest in cave-hunting began to be shown early in the present 
century. When Mr. Whidbey was appointed superintendent of 
the Breakwater Quarries, in 1812, he was requested by Sir Joseph 
Banks to examine any caverns he might meet with, and have any 
bones or other fossil contents carefully preserved.*' We are not 
told what was the originating cause of this request ; but so far 
back as 1786, at Kirkby, in Yorkshire, bones f had been discovered 
in limestone fissures, and used for road-mending. Possibly the loss 
of this opportunity prompted the action taken with regard to 
Oreston. Nor was the attention given without result. In 1816 
an ossiferous fissure was discovered at Oreston ; and this was the 
first bone cave in England which was made the object of scientific 
enquiry. 
In November of that year a number of bones of the rhinoceros, 
portions of the skeletons of three distinct animals, in a perfect 
state of preservation, were found embedded in clay in a cavern near 
the base of the cliff. The cavern was 160 feet in the hill from the 
original edge of the cliff, and was reached after blasting away 
60 feet of the rock horizontally (100 feet having been previously 
removed). The face of the rock was 74 feet perpendicular above 
high- water mark. The bones were found at a depth from the sur- 
* Sir Everard Home, "Phil. Trans.," 1817, part i. pp. 176-182. Cited 
" Devon. Assoc. Trans." vol. v. part i. p. 249. As Mr. Pengelly's valuable 
resume of the Oreston cave literature is generally available, while the original 
authorities are not, I give in each case the double reference. 
f They were human. Vide Col. Hamilton Smith's "Nat. Hist. Human 
Specks," pp. 94, 453. 
