A Trip to Mar del Plata 199 



subject. There was nothing, however, in the Upper 

 and Middle Pampean as displayed in cross-sections at 

 Mar del Plata which would lead me to think of the 

 deposits as possessing the relatively great antiquity 

 which would be implied in the reference of these beds 

 to the Eocene, or even to the Miocene. I saw nothing 

 which would incline me to believe these beds to be of 

 earlier age than the Pleistocene, or possibly the late 

 Pliocene. 



After having taken a look at the formation, as -it 

 first presented itself to view, we set about searching for 

 fossils. The Doctor presently called to me, and pointed 

 out one of the scutes, or thick bony plates, which had 

 once been a part of the armor of a Glyptodon, which was 

 embedded in the matrix. It only took a minute to 

 secure the specimen. Presently we found a place where 

 some ribs of a Megatherium were protruding from the 

 surface of the cliff. We dug these out. Then we found 

 some fragmentary remains of a Mylodon. The lower 

 jaw of a small rodent, beautifully preserved, was the 

 next discovery. A little farther on I found a well-pre- 

 served shoulder-blade of Paleolama, an animal which 

 was related to the guanaco. While I was finishing the 

 task of cutting this bone out of the matrix, my com- 

 panion called to me excitedly and beckoned me to come 

 to him. When I arrived at the spot he pointed to a 

 piece of what evidently was a potsherd projecting 

 from the dark chocolate-colored mass of the matrix 

 in which it was imbedded. This is worth all the cost 

 of this excursion!' he said. 'I have not touched the 

 thing. Look at it attentively. Tell me, has that thing 

 become recently imbedded where it is, or is it where it 

 has been for ages, until the waves ate their way into its 

 resting-place?' I knelt down and critically examined 



