186 



EARTH FEATURES AND THEIR MEANING 



ancestors. The bones of all these denizens of the caves lie en- 

 tombed within the clays and the sinter formations upon the cavern 

 floors, and they tell the story of a fierce and long-continued war- 

 fare for the possession of these natural strongholds. The evidence 

 is clear that these cave men with their primitive weapons were 



FIG. 195. Sinter formations in the Luray caverns, Virginia. 



able at times to drive away the cave bears, lions, and hyenas, and 

 to set up in the cavern their simple hearths, only in their turn to 

 be conquered by the ferocity of their enemies. Some of the Euro- 

 pean caves have yielded many wagonloads of the skeletons of 

 these fierce predatory animals, together with the simple weapons 

 of the primitive man. 



The Karst and its features. Most so-called limestones have a 

 large admixture of argillaceous materials (clays) and of siliceous 

 or sandy particles. Such impurities make up the bulk of the clays 

 and muds which are left behind when the soluble portions of the 

 limestone have been dissolved. 



Swallow holes we have found to be characteristic features within 

 such districts. When limestones are more nearly pure, as in the 



