560 [P"*. B.N.F.C, 



igth December. 



MR. ADAM SPEERS, B.Sc— " THE ORIGIN OF 

 CAVERNS IN LIMESTONE DISTRICTS." 



Mr. Spef.rs very fully described the various forms of caves, 

 and demonstrated by a successful chemical experiment the solu_ 

 bility of limestone in water charged with carbon dioxide. The 

 extensive deposits of limestone in Ireland and elsewhere are 

 acted upon in this manner. Thinly bedded rocks fall down 

 when they are thus undermined, but when the beds are very 

 massive they remain undisturbed, while the percolating waters 

 form great hollow spaces or caverns below, because the surface 

 rain waters percolating through the decaying vegetable matter 

 obtain a full charge of carbonic acid which dissolves the lime- 

 stone and forms channels for underground rivers, which, in the 

 course of ages, result in the formation of the caverns so very 

 common in all limestone districts, caverns which contain great 

 chambers decorated with fantastic groups of pendant stalactites 

 and stalagmites, built up on the floors by the evaporation of 

 lime-laden waters. As an example Mr. Speers described the 

 great mammoth caves of Kentucky which he had visited, and 

 which are found to consist of a series of chambers on five 

 different levels connected by miles of avenues through which 

 the visitor is taken by the guides. There are in this cave 223 

 avenues, 150 miles of which have been explored. There are 

 47 domes, one being 300 feet high ; 23 pits, one 175 feet deep ; 

 eight cataracts, three rivers, two lakes, and one sea The space 

 worked out of the limestone by the solvent and mechanical 

 action of water amounts to twelve million cubic yards. To 

 accomplish this work a vast period of time was required. 



Mr. Speers, taking his hearers from point to point in this 

 wonderful subterranean region, illustrated each by limelight 



