566 Trof. Spencer — On the Eastern Margin of N. Atlantic. 



were slowly developed into great and deep channels. We may not have- 

 sufficiently distinguished all the older from the newer features. As- 

 the amount of erosion performed may seem too great for the supposed 

 period of high continental elevation, we are willing to concede that 

 some of the continuations and enlargements of the more restricted 

 channels, or the erabayments terminating them, may be older 

 features, even possibly due in part to tectonic causes, whatever suclv 

 may be ; but this is a question beyond the confines of onr present 

 investigations. On account of the great slopes being indented by 

 the newer physiogi'aphic forms, we point out the evidence of the 

 subsequent stupendous elevation of the land. We may have to con- 

 cede to the Pleistocene period a really longer duration than has been 

 popularly supposed^ The growth of the valleys, under conditions of 

 variable rainfalls on the elevated plateaux, does give rise to such 

 features as we now find dissecting the submarine platforms ; and the 

 denudation under conditions of stupendous changes of level would 

 accelerate the excavation of the valley features, or modify them, as 

 described by Professor Hull and myself 



In place of pointing out the remarkable submarine holes and 

 burying the observations in the tomes of some learned society, we 

 have collected the phenomena and bound them together by a working 

 hypothesis based upon the grammar of geomorphy ; a new science 

 as yet not generally mastered, with results at first startling, although, 

 they only give expression to some of the changes of land and sea, 

 as taught by Lyell. Our imperfect studies have been met by 

 observations from a different standpoint, as if we did not accept 

 them in the common vray ; consequently, I do not see that any 

 unanswerable objection has yet been raised to our conclusions. 

 Hardly even enough to spur us on to seek for fresh confirmatory 

 facts. Mr. Hudleston would doubtless drift along with us if he 

 would give the subject the attention which it deserves ; and already 

 he says that he is not prepared to deny the connection between 

 Europe and Greenland in mid-Tertiary times, though he fails to 

 see any necessity for it. It was in the mid-Tertiary times that we 

 suppose the great undulating features of the Icelandic bridge began, 

 to be formed. I take it that further studies must lead him to- 

 distinguish between these features and the deep channels with their 

 tributaries, cirques, etc. But until this differential interpretation 

 of the forms is used, the great changes of level of land and sea. 

 in late geological times will doubtless appear startling. Whatever 

 agnosticism there may be concerning the correctness of our con- 

 clusions, so long as we are met by hypotheses substituting that of 

 subaerial erosion, it falls upon the advocates of such hypotheses to 

 sustain them with facts. While the changes of level of 3,000 feet 

 would perhaps meet with almost general acceptance, we have not 

 been shown any reason why this limitation should be made, when 

 the valley-like features extend to depths of 9,000 or 12,000 feet, as- 

 found by both Professor Hull and myself. 



