330 T. C. CHAMBERLIN 



old relatively, and the obvious recency of the upper part. The 

 method is certainly helpful in explaining the crowding into close 

 positional association faunas heretofore regarded as very different 

 in age. To that extent it gives relief to one of the most declared 

 phases of stress that make the case a really notable one. 



The one feature in this mode of analysis and interpretation 

 that may not be acceptable to some of the interested students 

 of the case lies in the fact that it not only permits but postulates 

 much transfer from a state of first burial in the flood-plain muck 

 to a state of later burial in the channel sands, and to still further 

 rehandling by the scour-and-fill process. However, this is not 

 that phase of transfer that has been most under discussion in the 

 history of the case. The interpretation suggested does not neces- 

 sarily involve any transfer from an independent deposit some- 

 where else to the creek deposits. It is purely negative on this 

 question, which is left to be decided pro or con by its own class 

 of evidence. 



A possible episode in the history of the Van Valkenburg's Creek 

 deposits must be suggested briefly to meet one other phase of the 

 deposits. There are specific grounds for thinking that the gradi- 

 ent of the creek may have been steepened, for a time, at some 

 period between that of its early adjustment to the sea as it retired 

 and its adjustment that now obtains at about the same level. 

 Some of the streams, harbors, and inlets in the region seem to 

 occup)' drowned valleys, and this has been held by Shaler, Matson, 

 and others to imply that a lower relative level of the sea, to the 

 extent of twenty or thirty feet, obtained for a time. Such rela- 

 tive lowering of the sea-level, if it occurred, would naturally have 

 caused Van Valkenburg's Creek to sink its channel — attended 

 perhaps by a flood-plain of greater or less extent also — into the 

 previous aggradation plain. As the sea-level again arose to its 

 present position, the sunken trench should have been refilled until 

 aggradation would be resumed on the level of the old plain. Such 

 an intervening stage in the drainage seems to harmonize well with 

 the browner color of the lower layer and with the division recog- 

 nized between the lower and the upper layers, the latter of course 

 being the assigned work of the resumed aggregation on the surface 

 of the old plain. 



