No. 4.] SPENCER — SURFACE GEOLOGY. 219 



region, and on the explanation of the origin of the. Great Lakes 

 themselves. 



The soundings do not show a conspicuous escarpment after 

 passing westward of the meridian of Niagara river, partly on 

 account of the sediments filling this portion of the lake, and 

 partly because the lake in all probability never had its channel 

 excavated to so great a depth as farther eastward. 



Attention must be called to the fact that the depth of the 

 Niagara river is 1.2 fathoms near its mouth, but that the lake 

 around the outlet of the river has a depth not exceeding four 

 fathoms with a rocky bottom. 



Another escarpment at the level of Lake Ontario, now buried, 

 was discovered by the engineers of the enlargement of the Wel- 

 land canal, according to Prof. Claypole (Can. Nat. Vol. ix. No. 

 4). When constructing No. 1 lock, at Port Dalhousie. it was 

 found that at its northern end, there was an absence of hard 

 rock which formed the foundation of its southern end. Rods 

 more than 40 feet long were pushed into the slimy earth without 

 meeting any hard rock bottom. This discovery will be noticed 

 in the sequel.^ 



Basin of Lake Erie. — The exceedingly shallow basin of Lake 

 Erie has its bottom as near a level plane as any terrestrial tract 

 can be. Its mean depth, or even maxima and minima depths 

 from its western end for more than 150 miles, scarcely varies 

 from 12 or 13 fathoms for the greater portion of its width. The 

 eastern 20 miles has also a bed no deeper than the western por- 

 tion. Between these two portions of the lake the hydrography 

 shows an area with twice this depth (the deepest sounding being 

 35 fathoms). This deepest portion skirts Long Point (the ex- 

 tremity, a modern peninsula of lacustrine origin), and has a 

 somewhat transverse course. An area of less than 40 miles lonsr 

 has a depth of more than 20 fathoms. The deeper channel 

 seems to turn around Long Point, and take a course towards 

 Haldimand county, in our Canadian Province, somewhere west 

 of Maitland. The outlet of the lake, in the direction of the 

 Niagara river, has a rocky bottom (Corniferous limestone.) 



The Dundas Valley and adjacent Canons. — We may con- 

 sider that the Dundas valley begins at the " bluff" east of the 

 Hamilton reservoir, and extends westward, including the loca- 



See Keport of Chief Engineer of Canadian Canals, 1880. 



