130 



HUNTING EXTINCT ANIMALS 



numerous shark's teeth, which though not conclusive, are 

 also of Miocene character; and finally and to my mind 

 conclusively, the cetacean remains of which there are a 

 good many, and which do occur in both the northern and 

 southern hemisphere, have been assigned all of them to 

 Miocene or later types. This study of the age was of great 

 importance to the Princeton Expedition, as their chief 

 collections were found just above this Patagonian layer. 

 To us it is equally important, as our collections all come 

 from below this layer and must therefore be older than the 

 Patagonian. 



To get at the conditions during the deposit of the Pyro- 

 therium beds in which we are chiefly interested, let us begin 



K 

 I 



I 



c:retA.ceou5 



Eocen* 



pi To- PleJjto- 

 ccoe cen« 



Diagram to Show the Rising and Fall of Patagonia as Indicated by the Rocks 



at the lower horizons and survey the series. At sea level 

 we found a thick layer of shales carrying marine shells of 

 shallow water types, especially various sorts of oysters. 

 Higher up the beds became sandy or clay with occasion- 

 ally a bed in which occurred marine shells and shark's 

 teeth. The major part of these beds, some 600 feet in 

 thickness, were barren, except as they had occasionally 

 some fossil wood in them. They are what Ameghino calls 



