248 H. L. FAIRCHILD PLEISTOCENE UPLIFT OF NEW YORK 



from 362, the present altitude, gives 110 feet, It will be noted that this 

 is the initial altitude of the Iroquois plane at Eome. All points of the 

 flooded area south of the fulcra! line will give the same initial altitude, 

 since they are derived figures ; but, of course, the original water level was 

 everywhere the same as the outlet. 



Checks and Proofs 



Several matters already presented in this paper fall properly under 

 this topic, but will not be repeated. There remains, however, a significant 

 coincidence which requires notice. 



The direction of the isobases of the map was determined, as stated 

 above, by comparison of the summit features of the marine waters in the 

 Hudson and the Connecticut valleys, and they indicate the total uplift 

 during Pleistocene time. It is an interesting and important fact that 

 Professor Coleman found precisely the same direction for the lines of 

 equal Iroquois uplift in the Ontario basin (95, page 363) . Yet the rising 

 movement discussed by Coleman belongs to only the later part of the 

 Pleistocene. Another coincidence is that Coleman drew his fulcra! line 

 of the Iroquois uplift through Quays and Eome, which is the precise loca- 

 tion of our isobase of 350 feet total uplift. If this is mere accidental 

 coincidence, it is quite remarkable ; but if it rests on verities in the 

 sequence of geologic events, it implies a true philosophy. 



At first glance the figures of the table show decided lack of harmony. 

 Quays is 557 feet above tide today, while Rome is only 460. While Eome 

 was rising in Glacial time 180 feet, Quays rose only 83 feet; but in post- 

 Iroquois time Quays rose 267 feet to Rome's 170 feet. How is it that 

 these two points, with such diverse uplift figures, can lie on the fulcra! 

 line of Iroquois tilting? Evidently they did not for the whole of Iro- 

 quois time. By plotting the data in a diagram the solution is suggested. 

 Quays was under the ice-sheet for a long time after Iroquois waters occu- 

 pied the southern portion of the basin, and during that time no uplift 

 occurred at Quays. When the land finally began to rise at Quays it had 

 already lifted 97 feet at Eome, and the water level stood at 207 feet. 

 From that time onward the two points lifted in comparative unison for 

 83 feet, or up to 290 feet, the height of Iroquois extinction. Now it 

 should be noted that the table shows that the present uplifted plane of 

 Iroquois started at 110 feet above tide at Eome and 207 feet at Quays. 



Again, it may be emphasized that the key to all such calculations is 

 found in the fixed vertical interval between the Iroquois and the marine 

 planes, taken in conjunction with the isobases of total uplift. If either 

 of these elements were wrong, the results would not agree with the facts 

 of observation. Students of the Pleistocene may find other ways of test- 



