AMERICAN JOURNAL OF SCIENCE. 



[THIRD SERIES.] 



Art. X LI V.— Terraces and Beaches about Lake Ontario ; by J. 

 W. Spencer, B.A.Sc., Ph.D., F.G.S., State University of 

 Missouri, Columbia, Mo. (Late Vice-President of King's Col- 

 lege, Windsor, Nova Scotia). With Plates VI and VII. 



[Read before the Montreal Meeting of the Amcrinm Association lorthc Advance- 

 ment of Science.] 



The extreme western end of Lake Ontario is separated by 



lieaeh from the open waters of the lake, and forms 



i Iky, having a length of about five miles, and a 



width of four miles at the eastern end, from which place it 



narrows to less than half a mile, at the western end. 



This triangular bay is bounded on two sides by the Niagara 



escarpment rising from four to five hundred feet above the lake. 



At a short distance westward of the bay, the two faces of the 



escarpment suddenly approach to within about two miles of 



;-. and thence extend parallel to each other for several 



miles, having formed the boundaries of a grand ancient river 



valley, through which the waters of the Lake Erie basin flowed, 



ivuivnm, as ;i rnbufarv. theGram! River, which drained the 



Is of the penii 3ula of western 



Ontario,— in Pre-glacia! tunes. This ancient valley is deeply 



filled with drift deposits, as described in a former paper read 



before the Association. Interglacial and modern streams have 



^^•ivatet] deep vallevs in the soft drift deposits producing a 



very broken country' throughout the whole Dundas valley, as 



represented on Plate VI. Along the sides of the escarpments, 



Am. Jotjr. Sci.— Third Series, Vol. XXIV, No. 144.— December, 1882. 



