PLEISTOCENE MARINE SUBMERGENCE 2$ 



probably marks the low water following the opening of the second, 

 Covey pass, outlet. If this is the correct interpretation then the 

 water level fell, in the shift from the Rome to the Covey outlet, 

 perhaps 40 or 50 or more feet. Then the rise of the land in the 

 Covey Hill district while the Covey pass carried the outflow of 

 Iroquois apparently raised the lake level about 22 feet at Richland 

 and 15 feet at Farr's, near Watertown. The increasing vertical 

 interval toward the southwest, and the character of the lower 

 beaches, suggest the work of rising water. 



This moderate rise of the land at Covey hill while the ice front 

 lay at that point was not recognized in former writings (27), but 

 it appears to be the only explanation of the shore features as 

 plotted in the diagram; and the best explanation of the excessively 

 elevated beaches in the Champlain district, described above. 



The profile for the uplifted marine plane is also drawn as a 

 straight line from Covey to Woodville, and beyond is given a curva- 

 ture parallel with the upper line of Iroquois. 



At Covey outlet the vertical interval between the closing Iroquois 

 and the sea-level plane is 290 feet (1030-740). It is thought that 

 no' appreciable uplift occurred while the waters were cutting and 

 melting their passage by the ice front on the steep north face of 

 Covey hill, during the down-draining of Lake Iroquois into the 

 Champlain waters at sea level. In horizontal distance on the north- 

 east face of Covey hill the fall from 1030 down to 740 feet is only 

 about one-half of a mile. Whatever rise of the district took place 

 during this episode must be negligible in this study. With this 

 view the vertical interval between the ^latest Iroquois and the 

 earliest marine planes must everywhere be 290 feet. The summit 

 marine features are fairly distinguished and fall into the profile 

 line, plotted by isobase intersections. The interval of 290 feet 

 marks the upper line of the Iroquois as the closing plane. And 

 it should be noted that beyond Richland, or south of the Rome 

 isobase, the Iroquois beach is a unit, a single heavy bar with steep 

 front; and this correlates with the upper line of the diagram. 



The unity of the western beaches suggests some close relation 

 between the closing level of the lake and the former Rome level. 

 It is possible that the lifting at Covey pass raised the closing level 

 to an equality with the Rome level in the western end of the basin. 

 The waters could not rise above the Rome outlet. 



Some variation of the bars in height from the profile is explained 

 by their distant location from the datum line (see plate 9) and 

 the direction of maximum uplift. It will be seen that the direction 



