No. 5.] WILKINS — EOZOIC ROCKS IN ONTARIO. 279 



It is composed of a gray and green slate conglomerate, weather- 

 ing greenish-gray, and very much resembling the slate conglome- 

 rate of Lake Huron belonging to the Huron ian system. The 

 base of this rock is a schistose gray orthoclase with green horn- 

 blende and epidote, while the pebbles are of Laurentian gneiss, 

 white and red micaceous and syenitic granite, syenite, felsite, 

 dolerite. diorite, epidote, chlorite and quartz, these masses being 

 generally rounded, particularly the gneissic pebbles, and very 

 rarely angular, while in size some exceed a foot in diameter, and 

 others are not over two or three inches. Excepting the rounded 

 character of the fragments, its agreement with the breccia de- 

 scribed on pp. 6 and 7 of Mr. Venuor's report on the Geology 

 of Hastings County is very close. The measures are somewhat 

 thin-bedded, some of the layers not exceeding one iuch in thick- 

 ness, and strike nearly uniformly N. 10 Q E. on an average, while 

 they have a uniform dip of E. 10^ 8. < 69°. They are inter- 

 sected by several quartz veins, having a general strike N. 40° E. 

 one of which averages sixteen inches in breadth. Boulders and 

 pebbles of the rock are of rare occurrence, and where found, i. e. 

 only on its south-west side, constitute a small percentage of the 

 erratics. No boulder of this character seems to be met with 

 further south- west than three miles from the rock. 



Although the line of junction with the Trenton limestone 

 is everywhere concealed, yet according to Professor McCoun 

 it was plainly visible many year ago before a quantity of 

 limestone had been quarried for building purposes ; the latter 

 was then seen overlying unconformably the slate conglomerate of 

 the ridge. On the west side the limestone forms several small 

 folds with east and west axes and moderate dips of 15° to 20 Q 

 to south and north. The summits of these anticliuals have been 

 denuded and partly filled with soil, the breadth of surface de- 

 nuded nowhere exceeding a hundred feet. As exposed on the 

 railway track, the limestone is intersected by two sets of joints 

 at right angles to each other, viz. one from north to south, and 

 one from east to west. On the east side the limestone is not so 

 well seen as on the west, and, where visible, occupies a much 

 lower elevation ; where seen, however, it has the same small cor- 

 rugations as on the west side, and these extend in the same 

 direction. The limestone has been most extensively denuded 

 upon the northern and north-western sides of the ridge, where a 

 bed of stratified sand and fine gravel at least fifteen feet thick is 



