38 



OUTLINES OF GEOLOGY. 



passed. Such grooves have been observed in England and 

 in the United States. 



82. Among the beds of diluvial gravel are some composed 

 almost wholly of shells. 



83. There are in many beds of stratified limestone, cav- 

 erns, some of which are of great extent. These are lined 

 with concretions of carbonate of lime, which, when pendant 

 from the roof, are called stalactites, and when forming a 

 floor, stalagmite. The floor has been broken through in 

 some of these caverns, and after passing through a bed of 

 stalagmite, a mass of diluvial gravel was discovered, in 

 which bones are imbedded ; and beneath this a second layer 

 of stalagmite was reached : on penetrating through the 

 latter the original rocky floor was finally discovered. 



The most celebrated of these caverns is that of Kirkdale 

 in England, discovered by Dr. Buckland. In this, and rest- 

 ing on the lower layer of stalagmite, were found the bones 

 of hyaenas, tigers, wolves, foxes, elephants, rhinocerosses, 

 hippopotami, horses, &c. Of these the skeletons of the 

 hysenas alone were complete , most of the others were gnaw- 

 ed, as by the teeth of the hyaena. It was hence inferred, 

 that before the catastrophe by which the diluvial gravel was 

 formed, this cavern had been inhabited by hysenas, who had 

 dragged in the bones of the animals on which they preyed ; 

 that England at that time had a climate suited for animals, 

 which are now only found within or near the tropics ; that 

 the whole of these races had been destroyed by the action 

 to which the diluvial gravel was due. By inference from 

 the thickness of the upper bed of stalagmite, it was conclud- 

 ed, that the epoch of this catastrophe was not more distant 

 than 4000 years. There are in England several other cav- 

 erns of the same description, among which are those of 

 Oreston, Callow, and Banwell. 



