26 



THE GEOLOGIST. 



BRITISH ASSOCIATION MEETING. 



( Continued from page 485 ). 



On the Ossifeeotis Caveens at Oreston. By Henry C. Hodge, of 

 Plymouth. Head before the Geological Section, Sept. 17, 1859. 



The constant removal of immense masses of limestone required for the pui'- 

 poses of the Breakwater at Plymouth, during the past half century, has from 

 time to time brought before the attention of geologists a series of remarkable 

 cavernous fissures of great interest, from the number and variety of fossil 

 remains of extinct animals contained in them. 



In the "Philosophical Transactions" for 1817, 1821, and 1823, will be 

 found some account of the earliest discoveries of these fossils, together with a 

 record of carefully conducted observations by Sir Everard Home and Mr. 

 Whidby (the engineer of the Breakwater at that time) respecting the circum- 

 stances under which they were met with. 



Mr. Whidby, in a paper dated Nov. 1816, mentions the striking fact that he 

 saw no possibility of the cavern in which the remains were met with having 

 had any external communication through the rock in which it was enclosed, 

 the surrounding limestone being everywhere equally strong, and requiring the 

 same labour to blast it ; and, with respect to the occurrence of stalactite, he 

 remarks that nothing of the kind was met with in the cavern in which the 

 bones were found, so that there is no proof that any opening in the rock from 

 above had been closed by infiltration. In the year 1820 more bones were met 

 with, lying on a thin bed of dry clay ; there also occurred here and there a few 

 small caverns, similar to that m which the bones were discovered ; and again 

 he states that none of them had the smallest appearance of ever having had 

 any opening to the surface, or connection with it whatever, or with each other. 

 The caverns here spoken of were quarried many feet below the bottom of them, 

 and nothing was found but hard solid limestone. He also adds, " that many 

 caverns have been met with in these quarries, the insides of which have been 

 coated with stalactite ; but there was no appearance of this kind in the cavern 

 where the bones were found, every part of it being perfectly dry, and nearly 

 clear of rubbish — a circumstance which clearly proves it had no connection 

 with the surface." 



During the summers of 1832-23, Mr. Jos. Cottle, of Bristol, obtained a large 

 collection of bones from the same quarries, and he has published some account 

 of them, and of the general circumstances of their occurrence. 



Since that period, it would appear that similar openings in the limestone 

 have been of not unfrequent occurrence, and it is known that some of them 

 have contained fossils ; but no systematic observations have, I believe, been 

 instituted with the view of penetrating their origin or history. 



The statements so confidently made by Mr. Whidby as to the perfect 

 enclosure of the caverns by solid limestone, have been confirmed by my own 

 observations, and this fact has not failed to surprize even the workmen engaged 

 in the quarry ; but it must be evident that at some period an opening did exist, 

 and it occurred to me that such might be most successfully sought for between 

 the surfaces of the beds of which the masses of limestone are composed. No 

 satisfactory conclusion could be di'awu from a careful examination of the rock 



