670 ROLLIN T. CHAM BERLIN 



distinct in some portions of the channel, but which at some other 

 points can be separated only with much doubt. At best they are 

 thin, both of them together averaging only 5-7 feet in thickness, and 

 they are quite changeable in composition. The lower of these has 

 been designated formation No. 2 by Sellards and the upper one 

 formation No. 3. In this paper the former will be termed the lower 

 creek deposit and the latter the upper creek deposit. The bones 

 and relics in question were found in these two creek deposits. 



The discrimination of these successive stages of formation made 

 it seem quite possible that the land life of the times began to occupy 

 this region during the stages of emergence, and hence that bones of 

 the extinct mammals and other vertebrates might have accumulated 

 in the marshy area to the west of the Vero beach ridge in Pleistocene 

 times, following not long after the coquina stage, and that later, 

 as Van Valkenburg's Creek gradually cut back into this area, these 

 old Pleistocene bones were washed into the stream channel and 

 concentrated in the creek deposit, while at this later time there 

 mingled with them relics of the more recent vertebrates and plants, 

 as well as human remains. 1 Thus the deposit of the stream channel 

 might contain fossils of quite different ages in intimate association. 

 The geologic conditions and the sequence of events seemed such 

 as to suggest and to support this hypothesis. 



On the assumption that the extinct mammals were perhaps as 

 old as Middle Pleistocene — as was then urged — and that the 

 coquina formation which underlies the region could not well be 

 interpreted as much older than this — if indeed as old, since all of 

 its fossils belong to living species — there seemed to be rather urgent 

 reasons for presuming that at least the older of the extinct mammals 

 invaded the region as soon after its emergence from the sea as con- 

 ditions permitted. They were therefore supposed to have been 

 present during the formation of the marsh deposit back of the 

 beach ridge, and to have, in all probability, been buried in it, and 

 their relics derived from it in the subsequent trenching and filling 

 by Van Valkenburg's Creek. The finding of balls of black sand- 

 stone from the marsh deposit in both the older and the younger 

 creek deposits seemed to fit at once, and help explain, this very 



1 Symposium, pp. 25-39. 



