82 TRANSACTIONS OF THE [.TAN. 13, 



of the Hudson, in the Highlands, there are the cascades of 

 Broccy Falls east of Anthony's Nose, and of Indian Creek at 

 Garrison's, equal in altitude to any on the west bank ; and as 

 further evidence of the stability of this river valley, the Cham- 

 plain terraces on the east bank are of the same height as those 

 on the west. 



The topographic trough which extends from the mouth of the 

 Raritan to the Delaware, and which has been discussed by Mr. 

 McGoe as a result of displacement,' appears, from its relations to 

 the Mesozoie strata, to be a trough of erosion. It is evidently 

 the southward extension of the trough which has been excavated 

 in the Triassic formation between the Palisade ridge and the 

 first Newark mountain. 



The hypothesis suggested in this paper as a tentative explana- 

 tion of the Quaternary differential elevation of the continental 

 margin in the vicinity of New York, seems to satisfy the con- 

 ditions imposed by all the facts yet reported in the study of 

 the Quaternary marine and estuarine deposits of the Atlantic 

 coast. It remains for future investigation to prove it or disprove 

 it. On theoretic grounds it cannot be considered impossible that 

 an uplift should have occurred in Quaternary time along the 

 mountain axes of the Appalachian system. The writer is in- 

 formed by Prof. N. S. Shaler that in Massachusetts there is sat- 

 isfactory evidence of a northward uplift. This may be attri- 

 buted to elevation of the White Mountain region. Elevation in 

 the Adirondack and Green Mountain areas would explain the 

 presence of Quaternary marine deposits at an altitude of nearly 

 400 feet in the basin of Lake Champlain. An examination of 

 the data accessible to the writer suggests to him that the 

 highest terraces are on the flanks of mountains, and that the 

 lower deposits are proportionately remote from them. 



Of some significance in this speculation is the form and rela- 

 tive altitude of the ocean-bottom. 



If there had been a Quaternary elevation of the continental 

 margin toward the north, there should have been a consequent 

 diminution of the depth of the sea, and, where the sea-bottom 

 is unaffected by shore deposits or by erosive agencies, there 

 should remain some evidence of this diminution. The parallel- 

 ism of the 100-fathom curve to the general trend of the Ap- 

 palachian system south of latitude 40° North, appears to be 

 significant of a relation between the attitude of the coastal plain 

 and some orographic movement in that system. 



North of latitude 40" North, off the coast of Massachusetts, 

 the position and direction of the 100-fathom curve suggest a 

 more northerly uplift. 



1 Op. cit. 



