REVIEWS 499 



beaches and terraces were found at 378 and 528 feet. Drinkwater reports observing 

 a beach about 600 feet above the sea on the hills above O'Brien Harbor at Cape 

 Chidley. Shells of Saxicava rugosa and Mya truncata were found imbedded in till on 

 one of the Islands of God's Mercie at 200 feet, and the Saxicava shells in drift at lakes 

 Gertrude and Greely at no feet. 



Chalmers, Robert. Notes upon the Pleistocene Marhie Shore Lines and 

 Land Slips of the North Side of the St. Lawrence Valley. Geol. Survey 

 Canada, Vol. XI, Part J, Appendix I, pp. 63-70, 1901. 



The marine plain or bottom land of the St. Lawrence valley extends from 8 to 30 

 miles north of the river in the district between Quebec and Montreal. The river bank 

 is usually but 15 to 25 feet, but in passing back toward the northern limits, along the 

 base of the Laurentian hills, there is a rise to 400 or 500 feet. The slope is terraced, 

 apparently by marine shore action. The shore lines are found to increase in height 

 from east to west, the rate of rise of the highest one between Quebec and Lachute 

 being about two feet per mile. 



The landslips here reported have occurred at various dates from 1840 to 1898, and 

 lie below the level of the highest shore line. The most recent one, May 7, 1898, filled 

 the Riviere Blanche valley 25 feet for a distance of nearly two miles. The cause of 

 the landslips is stated by the author to be due to (i) the silty and arenaceous character 

 of the Leda clay, rendering it capable of absorbing and retaining a large amount of 

 water, and (2) the increased precipitation during the season these landslips occurred, 

 which saturated the deposit and gave them greater weight than usual. 



Chalmers, Robert. Surface Geology of Part of Ontario. Geol. Survey 



Canada, Summary Rept. for iqoi, pp. 158-68. 



In company with R. W. Ells, the western limit of marine beds was traced north- 

 ward from Brockville to Smiths Falls. Clay thought to be of fresh-water deposition 

 was noted at Lyn, Gananoque, Kingston, and westward. 



Oil wells at Petrolia, Oil Springs, and Sarnia penetrate 100 to 125 feet of surface 

 deposits before striking rock. Rock is reached near Bothwell at 210 feet and at 

 Button at 255 feet, while at Tilsonburg it is reached at 74 to 81 feet. 



In parts of the Thames valley gas is obtained from sand and gravel below hard- 

 pan at a depth of about 90 feet. 



The following series of drift beds is reported to occur in western Ontario : 



1. Surface clay, sand, or gravel, more or less oxidized. 



2. Bowlder clay of irregular thickness, sometimes wanting. 



3. Sandy and silty beds, in places forming the upper part of the Saugeen clay 

 (interglacial). 



4. Saugeen clay, interglacial, partially oxidized and somewhat sandy in upper 

 part, fresh-water shells in lower part. 



5. Erie clay, interglacial, color bluish-gray, sometimes darker, stratification more 

 or less distinct; contains fresh-water and land shells (Campeloma, Succinea, Polygyra, 

 etc.), in upper part ; localities noted are Pelee Island and shore of Lake Erie. 



6. Bowlder clay, usually a thin sheet resting either on the decomposed or the 

 solid surface of the " fundamental rocks." 



The so-called interglacial beds Nos. 3 to 5 often have a combined thickness of 

 100 to 150 feet. 



