BONE CAVERNS. 91 



28. The pliocene beds of the United States seem to belong 

 chiefly to a very modern period ; they exist to a great extent in 

 several localities. At the mouth of the Potomac, in Maryland, is 

 a series of clay beds, alternating occasionally with sand. All the 

 fossils found in these beds are identical with those species found 

 living on the neighbouring sea-coast, a positive indication of the 

 newness of these beds. Similar beds exist at Niagara and in 

 Kentucky, and in other parts of North America ; in ali cases the 

 recent deposits are very striking. 



29. While these lacu'strine deposits were tranquilly forming be- 

 neath the waters, the then uncovered surface of the earth was in- 

 habited by hyenas, cavern bears, hairy elephants, ma'stodons, rhi- 

 noceroses, hippopo'tami and other animals belonging to genera still 

 in existence, but the species of which are now lost ; they appear 

 to have been destroyed in the geological revolution which raised 

 up the principal chain of the Alps, and gave to these mountains 

 their present configuration, and its present shape to the European 

 continent. It is probable, too, that the same revolution destroyed 

 the multitude of animals whose bones are found at the bottom of 

 certain caverns or fissures in the rocks, where they are buried in a 

 sort of calcareous cement, ordinarily of a reddish colour. 



30. BONE CAVERNS. The most ancient caverns, celebrated for 

 the remains of mammals which they contain, are those of'Harz 

 and of Franconia ; but since Dr. Buckland has shown the pro- 

 priety of removing the mud, sands, rolled flints-, stala'gmites, &c., 

 which often cover the bone collections, these remains have been 

 found everywhere, even in places where they had not been pre- 

 viously supposed to exist. 



31. Most of these caverns appear to have had one or more 

 lateral openings, affording easy entrance to the animals that fre- 

 quented them, as places of refuge, to devour their prey, and finally 

 they came to them to die. Here their bones accumulated through 

 a great many generations, and we now find them buried in a dark 

 earth, in or on which we recognise their dejections. Often we 

 find among the bones of a certain genus of animals other bones, 

 having upon them the print of teeth, showing they had been the 

 prey of the first. The greater number of these bones belong to 

 the bear tribe, two species of which were larger than any now 

 existing ; or to the hyena tribe, also larger than those now known. 

 Sometimes one, and sometimes the other of these genera predomi- 

 nates ; a species of wolf abounds in the bear caverns of Galenreuth 

 in Franconia : other carni'vora, of the genus dog, and those of the 

 genus cat, including species of cougars, are everywhere in small 



28. In what parts of the United States do pliocene beds exist? 



29. Wh it kind of animals inhabited the land while these lacu'strine de 

 yosits were being formed ? 



30. What are bone caverns ? 



31 What are the features of bone caverns ? 



29 



