LATE PLEISTOCENE OSCILLATIONS. 
5 
The Upper Limit of Marine Submergence. 
The upper limit of marine submergence in the vicinity of 
Ottawa was determined in 1891 by Baron Gerard de Geer of 
Sweden. The altitude of the highest shore-line, as determined 
by barometer, was found by de Geer to be 705 feet above the 
sea. 1 
In 1903, R. Chalmers stated that he had remeasured the 
altitude of the highest shore-line at Kingsmere, near Ottawa, and 
found it to be 910 feet above the sea. 
Considerable difficulty arises in attempting to determine 
the highest shore-line in the Ottawa valley owing, partly, to the 
fact that the highest beach is never strongly developed, as, 
apparently, the sea did not stand long at the highest level, and 
partly because at the higher altitudes the slopes are generally 
steep and rocky with little drift covering so that little material 
was available for construction of wave-built features. Two of 
the most favourable localities for observing the shore-line are at 
Kingsmere, 8 miles northwest of Ottawa, and at Rigaud mountain, 
70 miles east of Ottawa and 30 miles west of Montreal. 
The Kingsmere locality is one of the most favourable 
localities in the Ottawa valley for the determination of the 
upper marine limit because of the occurrence of a sheet of 
boulder clay on the southern slope of the “mountain” and 
because of the good exposure to wave action. In the stream 
valley leading up to Kingsmere from the east, a deposit of strati- 
fied sands and gravels occurs, overlying stratified clay. The 
upper limit of the stratified sands and gravels is sharply defined 
and forms a terrace. The altitude of the inner edge of the 
terrace, as determined by levelling from the first road corner 
above this locality, the altitude of which is given on the Ottawa 
map sheet, issued by the Department of Militia and Defence, as 
796 feet, was found to be 688 to 690 feet above the sea. The 
boulder clay slope rises to an altitude of over 200 feet higher, 
but no evidence of wave action could be found above an altitude 
of 690 feet. This locality is probably the same as that at which 
de Geer determined the altitude of the highest shore-line to be 
1 De Geer, Gerard, “On Pleistocene changes of level in eastern North America," Proc, 
Nat. Hist. Soc., Boston, vol. XXV, 1892, pp. 454-477. (Map.) 
