2IO The Ottawa Naturalist. [February 



part of Tudor, but it is with the more easterly of these that 

 the occurrences to be described were noticed. 



This batholite has an irregular, though somewhat oval, out- 

 line, presenting a series of bays witti occasional small arms, 

 the former occupied by wedge-like areas of the clastic rocks. It 

 covers the northern portions of con. XIX of Tudor and 

 the southern part of first concession of Limerick, extend- 

 ing from lot i6 in Tudor eastward to and beyond lot 9. The 

 area characterized by its presence is exceeding rough and 

 barren, presenting as usual a series of low rounded hills with 

 occasional precipices and intervening swampy flats. Macro- 

 scopically the composing rock is medium textured, of a distinct 

 though pale flesh colour, weathering white where exposed to 

 atmospheric agencies. To the unaided eye it has every 

 appearance of an ordinary granite and would undoubtedly be 

 classified as such by most observers. Under the microscope, 

 however, plagioclase is seen to be greatly preponderant while 

 hornblende is the most abundant ferromagnesian constituent, 

 although biotite altered to chlorite is likewise present. The rock 

 must therefore be placed with the diorites although it evidently 

 represents a rather acid type. Associated with this rock and 

 apparently a diflerentiation product of the same magma is a 

 massive gabbro-diorite. The coloured constituent shows the 

 deep green borders and pale interiors characteristic of uralitic 

 hornblende, although the alteration of the original pyroxene is 

 quite complete. Many individuals show a tendency to assume 

 the actinolitic habit, and areas and patches still more intimately 

 associated with the more acid phases of the rock are rather typi- 

 cal amphibolites, the hornblende and other constituent minerals 

 having undergone still more extensive deformation and dis- 

 location. 



The place where these supposed conglomerates were first 

 noticed was on lot 13 in con. XIX of Tudor, a short 

 distance north of Beaver Creek. At this locality, some angular 

 boulders composed of this material and evidently carried thence 

 from a source not far distant, were deposited from the drift-laden 



