TITLES AND ABSTRACTS OF PAPERS 65 



in the form of a profile, a large number of measurements of altitude of tribu- 

 tary deltas and other gravel deposits, which are shown to conform not to a 

 single northward-rising plane, but to a steplike series of such planes, alternat- 

 ing with shorter, steeper curves — the whole profile thus suggesting that of an 

 ungraded river or chain of lakes subsequently upwarped. 



It seems to me that still greater difliculty awaits Professor Fairchild in the 

 eastern part of Massachusetts, where his isobases if extended, everywhere 

 curved considerably, would seem to require marine submergence of 300 to 400 

 feet. The evidence near Boston in outwash gravels with kettle holes, within 

 30 feet of sealevel, seems impossible to reconcile with such deep submergence. 



The general session adjourned at 12.30 o'clock p. m. 



At 2.30 p. m. the Society met in joint session with the Paleontological 

 Society and listened to the address of Dr. Charles D. Walcott, President 

 of that Society, on "The Cambrian of Western North America." 



At the close of this address the Society reconvened in sections as before. 



TITLES AND ABSTRACTS OF PAPERS PRESENTED BEFORE THE FIRST SECTION 

 AND DISCUSSIONS THEREON 



The first section convened at 3.48 o'clock p. m., with Vice-President 

 R. D. Salisbury in the chair and E. 0. Hovey acting as secretary. The 

 following papers were offered : 



CAUSE OF THE POSTGLACIAL DEFORMATION OF THE ONTARIO REGION 



BY J. W. SPENCER 



(Ahstract) 



The measured postglacial deformation between the head of Lake Ontario 

 and Parishville (near Potsdam, New York) is 540 feet, and to this must be 

 added 120 feet for the Erie region east of Cleveland. Some have attributed 

 this movement to the removal of the ice-sheet. 



The anomalies of terrestrial gravity (Hayford and Bowie) show an excess 

 of terrestrial weight at Potsdam equal to 700 feet of rock, but at the northern 

 end of Lake Champlain, where the glaciers were thick, there is now only an 

 excess of 35 feet, while at Albany there is a deficiency of 1,435 feet, at Ithaca 

 765 feet, and at Cleveland 100 feet (all in glacial areas). The deformation 

 below the outlet of lake is seen to be connected with the earth movements 

 quite independent of the ice-sheet ; the earth movements seem to be related to 

 the Laurentian mass and ahnost independent of the Adirondack outlier." 



Presented in abstract without notes. 



I'^Am. .Tour. Sci., vol. xxxv, pp. 261-273. 



V — Bull. Geol. Soc. Am., Vol. 25, 1913 



