POST-JURASSIC HISTORY OF THE NORTHERN APPALACHIANS 693 



An important question on which Professor Barrell did not explicitly state 

 his opinion is: What was the form of the land area in which the sea cut the 

 broad platforms and low cliffs that he describes as occurring at successively 

 lower and lower levels? The land seems to have had a hilly or mountainous 

 surface in the background, as has long been recognized in the description 

 which treats the uplands of southern New England as an uplifted and dissected 

 peneplain; and in the foreground there was a buried land surface of small 

 relief, which the Potomac or some other formation still covers unconformable, 

 this buried surface being an element that is common to both the earlier and 

 the later view. But what sort of surface existed in the broad belt of country 

 between the background, not invaded by the sea, and the foreground, still 

 covered by stratified deposits? It seems conceivable that this intermediate 

 belt, as well as the buried foreground, may already have had a moderate or 

 small relief more or less interrupted by monadnocks, and a general slope to 

 the southeast, when it was exposed to the attack of the sea; it may, indeed, 

 have served in this reduced condition as the floor on which a heavy subsiding 

 marine strata were laid down during the advance of the sea on the subsiding 

 continent ; and the advancing sea may have even then trimmed and shaved the 

 subsiding land at successively higher and higher levels ; and in this case the 

 retreating sea has had, during each pause in its retreat, to clear away the inner 

 extension of the overlapping strata before it could bench the underlying floor. 

 But all this may have happened without producing a great amount of change 

 in the form of the preexistent surface of the intermediate belt ; and if thus 

 interpreted, this belt might be called a sea-benched peneplain. If, on the other 

 hand, the work of the sea was more profound, the resulting surface would be 

 best described as a series of broad sea benches or platforms, separated by low 

 cliffs. 



Let me turn to another aspect of this problem. In the outline of method 

 written on the blackboard in explanation of my paper, that preceded Professor 

 Barren's, there were certain headings of which no mention was made in my 

 remarks. One of these, in the column of safeguards, was the word hospitality, 

 which indicated the attitude that an investigator should strive to maintain 

 toward all new theories, particularly toward such as may replace his own 

 preferred view ; for in this way he can best guard against the serious danger 

 of favoritism. I confess freely that it is difficult immediately to take a per- 

 fectly hospitable attitude toward a new theory 7 that will very likely be substi- 

 tuted for an earlier one of my own which I have held for more than twenty 

 years with growing faith in its competence, but I propose to do my best to 

 assume the proper attitude toward the new view, and hope that the recog- 

 nition of the difficulty of this duty will make it easier. With hospitality should 

 be associated responsibility. It is not appropriate for one investigator to leave 

 to others the duty of testing any theory that enters into the solution of his 

 problem ; but here I do not expect my practice to equal my principle. It is 

 not likely that I shall take up new field study of this problem ; and the ad- 

 mirably fair and competent treatment that it is receiving from Professor Bar- 

 rell, along with my abundant occupation at present in other directions, is my 

 excuse. Revision of opinion is another safeguard against error; thai 1 shall 

 hope to make whenever need be; and under the lead of this heading Professor 

 Barren's paper, when printed, will receive the most attentive consideration. 



