THE FOCUS OF POSTGLACIAL UPLIFT 59 



Triangles between 



Hamilton, Lewiston, and Scarboro, 1 2 feet, N. 22 E. 

 Lewiston, Rochester, Colborne, Ont., 2.5 feet, N. 17 E. 

 Rochester, Sodus, Trenton, Ont., 3.6 feet, N. io° E. 

 Sodus, Rome, east of Watertown, N.Y., 5.5 feet, N. 3 E. 



These lines converge approximately in lat. N. 49° E., and long. 

 76 W. With the revised figures, the longitude is found to be the 

 same, while the latitude is only 60 geographical miles north of the 

 original determination, with the meridian of maximum uplift 

 found to be just beyond the eastern end of Lake Ontario as origi- 

 nally computed. 



Based upon the rise of the Algonquin beach east of Lake Huron, 

 the mean rise in the triangles is found to be : 



Between 



Grand Bend, Southampton, and Rosedale, 1 .3 feet per mile, N. 35° E. 

 Holland Landing, Wyebridge, and Rosedale, 3 .4 feet per mile, N. 23 E. 

 Bradford, Owen Sound, Wyebridge, 3 . 1 feet, N. 27 E. 



Combining the former of these triangles with those about Lake 

 Ontario, the lines of rise from Grand Bend, and from Holland 

 Landing, converge to the same point as those from Lake Ontario, 

 but if the mean rate for the third triangle (which takes in a more 

 western equivalent) be used the focus will be in about lat. 48 N. 



Upham, Taylor, and Leverett have found the rate of rise in the 

 region to the northwest to be of smaller amount, where Gold- 

 thwaite suggests that the rise also somewhat coincides with the 

 height of land as found by me farther east in 1888, where the 

 maximum amount is computed at some 250 miles north of Ottawa 

 City, or a few miles to the west of this meridian. 



The inferences to be drawn from these observations are: (1) 

 that until a downward slope shall be found, we should conclude 

 that the rise described continues to near the region indicated, 

 beyond which the postglacial warping is downward; (2) that 

 eastward of the 76th meridian, for any assumed latitude, the post- 

 glacial rise disappears and comes to be replaced by a downward 

 slope. This is a question that has given the writer much solicitude, 

 in an effort to determine the locus of downward warping in the 



1 At a point 12 miles east of Toronto. If, in place of this, the elevation at Carl- 

 ton (5 miles west of Toronto station) be taken, the line of rise is found to be N. 27 E. 



