716 PROCEEDINGS OF THE OTTAWA MEETING 



The sealevel attitude is so nearly a certainty that the term "gulf" seems appro- 

 priate, and the water is named after Doctor Grove Karl Gilbert, who was the 

 first geologist to note the beaches and appreciate their significance, and who has 

 had special interest in and knowledge of the Pleistocene features in the Ontario 

 basin- 

 After mapping the shore features shown in figures 1 and 2 the plane of the 

 water surface was projected northward, and it was calculated that it would 

 lie on the highest ground near Clayton, and specially on a hill 4 miles south- 

 west of the village. A visit was made to the locality and the shore features 

 found precisely as expected. These are shown in figure 3. The "hogback" 

 hill carries remarkably strong spits and cliffs, and good bars at corresponding 

 levels occur on the east. If the contour of 440 feet on the hill summit is cor- 

 rect, then the shore features have an altitude of about 400 feet. Good bars 

 are found 3 miles south of Clayton on the 400-foot contour. Two miles south- 

 west of the village, on the road to the "hogback" hill, is a hill by the Tiernan 

 corners with good spits and cliffs at about 350 to 360 feet, by the map, and 

 west of the corners is a gravel plain more than a mile long with map altitude 

 of 380 feet. 



On the supposition that the highest shore features represent the work of 

 marine waters, we conclude that the total uplift of the land at Clayton has 

 been 400 feet since the initiation of the Gilbert gulf. Taking the altitude of 

 the water plane southwest of Clayton as 400 feet and the distance to the Texas 

 spit as 46 miles, we find the gradient to be 3 feet per mile in direction 6 degrees 

 east of north. This suggests that the tilting is steeper toward the north, which 

 .Is confirmed by an examination of the planes. The stretch from Texas to 

 near Henderson gives 2.5 feet per mile. The stretch from the latter point to 

 the "hogback" hill gives 400 — 315 -*- 25.5 = 3.3 feet per mile. 



It is important to compare these gradients with those of corresponding sec- 

 tions of the Iroquois shoreline, which lies nearly parallel and only 5 to 9 miles 

 distant on the east. The section from Richland to Adams compares well in 

 direction and position with the Gilbert Gulf beach from Texas to near Hender- 

 son, and the gradient is 640 — 566 -=- IT = 4.4 feet. It appears that this is 

 nearly twice the tilt of the marine plane. From Adams to Farrs (3 miles 

 east of Watertown), but in a direction more northeasterly, the gradient is 

 740 — 640 -s- 14.5 = 6.9 feet per mile. This also is about twice that of the 

 marine plane north of Henderson. The entire distance between Richland 

 Junction and Farrs gives, 740 — 566 -f- 30 miles = 5.8 feet per mile, which is 

 almost double the grade of the marine plane from Texas to Clayton. Making 

 allowance for uncertainty in the relation of the several datum points to the 

 water planes and for the short distances involved, the harmony in the quantita- 

 tive relations of the two shorelines is striking. It appears that the deforma- 

 tion of the Iroquois shore is just about twice that of the marine shore. In 

 other words, one-half of the post-Iroquois deformation occurred in the time 

 between the formation of the two beaches, and the other half since the upper 

 marine beaches were deserted. This seems disproportionate, as the fall from 

 Iroquois to Gilbert gulf was only a downdraining of the lake waters through 

 perhaps 230 feet of vertical distance, while the uplift of the land at Clayton 

 has been an exceedingly slow movement through 400 feet. We conclude either 

 that the draining down of the sub-Iroquois waters covered a very long time, 



