286 MAN AND THE MASTODON. 



undermined by a rivulet. This case, however, is also open 

 to doubt, and Sir C. Lyell was of opinion that this bone might 

 have been derived from one of the Indian graves, which are 

 very numerous in this locality. Dr. Usher, on the contrary,* 

 regards it as "an undoubted fossil," belonging to the same 

 period as the remains of the mastodon with which it was 

 discovered. Count Pourtalis records the discovery of some 

 human bones in a calcareous conglomerate, estimated by 

 Agassiz to be ten thousand years old, though it must be 

 added that this calculation has been disputed by the Count 

 himself. 



The so-called "Calaveras" skull was found in the county 

 so named by Mr, Mattison, who assures us that he took it 

 with his own hands from a bed of gravel 130 feet from the 

 surface and under four layers of lava. The antiquity of this 

 skull has been much questioned, but Mr. Whitney seems to 

 feel no doubt on the subject. He maintains^ that the chemi- 

 cal condition proves that it is of considerable antiquity, and 

 not a mere modern skull, as some have supposed. Of course 

 if it really belonged to the bed in which Mr. Mattison sup- 

 poses that it was found, it must be of great antiquity, but we 

 do not know enough of the locality to be able to form even 

 the vaguest idea of its age. 



Dr. Douler obtained from an excavation near New Orleans 

 some charcoal and a human skeleton, to which he was inclined 

 to attribute an antiquity of no less than fifty thousand years. 

 The plain on which the city of New Orleans is built, and 

 which rises only about ten feet above the sea level, consists 

 of alluvial soil, which has been proved by borings to have a 

 depth of more than five hundred feet, and which contains 

 several successive layers of cypresses. The river banks show 

 similar remains of ancient forests, and Messrs. Dickeson and 



* Dr. Usher, in Nott and Glid- t Whitney, Auriferous Gravel? 

 don's Types of Mankind, p. 344. of the Sierra Nevada, p. 271. 



