INVESTIGATION VERSUS PROPAGANDISM 325 



from 1 9 13 — when the digging of the canal interrupted the normal 

 work of the creek — for two hundred centuries should give a fairly 

 firm first step in interpreting the actual six feet of creek deposits, 

 if these are to be interpreted as simple aggradational accretions 

 that have escaped reworking. If, on the other hand, reworking 

 has seriously influenced the case, some of the criteria thus far 

 much insisted upon may be brought into question. 



Such an inquiry might start from two questions: (i) What is 

 the normal thickness of vegetal muck and sand that might reason- 

 ably be expected to accumulate in such a situation during the 

 Recent Period?- (2) What is the minimum amount that can 

 reasonably be thought to satisfy the demands of the case? The 

 first question looks simply to the most rational estimate of work 

 done; the second is influenced by a desire to leave as much as 

 possible of the six feet of the actual deposit for assignment to 

 earlier stages to help reconcile the shallow depth of the deposit 

 with the faunal evidences that imply a great lapse of time. This 

 finds its justification in the fact that a heavy stress is put on inter- 

 pretation somewhere, and it is in the line of reconciliation for each 

 advocate of a particular view to leave as much leeway as he can 

 consistently for the accommodation, of conflicting views. This in 

 the end may be found to be the only way to save his own criteria 

 from serious challenge. 



To realize the grave nature of the stress which the case presents 

 in only one of several particulars, let us for the moment suppose 

 that the rate of aggradation on the flood-plain of the creek is no 

 more than one inch per century; the total aggradation of the flood- 

 plain in the two hundred centuries assigned the Recent Period 

 would be more than twice the whole six feet actually shown in the 

 creek sections. The supposition is of course merely illustrative. 



Preliminary to any true estimate of an actual deposit of this 

 type, it is necessary to inquire how a creek does its aggrading work 

 on a low gradient plain of its own formation when controlled by a 

 sea-level near at hand. Whatever else is involved — and there is 

 much that cannot be noted here — two quite different classes of 

 work are involved: (i) that done upon the flood-plain which occu- 

 pies all the creek bottoms not at the time included in the creek 



