Frof. Bonnet/ — Rock-specimens from the Canadian Rockies. 5i7 



of Mount Stephen, between it and Mount Dennis. The rock from 

 the summit [2021] is a flattish slab, formed by a vein of quartz, 

 from about a quarter to nearly half an inch in thickness, slightly 

 iron-stainad on both sides, with a little pale greenish-grey phyllite 

 adhering, in which are some more distinctly micaceous streaks, the 

 rock no doubt having been much affected by pressure. On the west 

 bank of the Kicking Horse River, facing Mount Stephen, is Mount 

 Burgess. From the summit one of Mr. Whymper's guides brought 

 a piece of dark grey limestone [2039] resembling one from our 

 Lower Carboniferous. Under the microscope it is found to consist 

 of minute grains of calcite, of a pale brownish-grey tint, in which 

 thin brown lines indicate a rude cleavage ; two or three cracks being 

 filled by calcite. It is probably a pressure-modified limestone. 

 From the base of the mountain, about one-third of a mile from 

 Field and nearly at the level of Hector Pass, two specimens were 

 collected from rock exposed in blasting a road to the Emerald 

 Lake. One is a chip of rather dark compact limestone, weathering 

 to a paler tint, not unlike the summit rock; the other is a similar 

 rock, but covered in parts with a tufaceous deposit. Mr. Whymper 

 remarks that round about Field, or, indeed, at most places in the 

 Eockies, which have nearly the same elevation above the sea, it 

 is very difficult to find rock in situ, for it is masked by forest or 

 buried under vast quantities of soil or debris. 



The next specimens come from mountains some fifteen miles to 

 the north-west of Field and to the south-west of Mount Collie, or 

 from a mass forming a kind of spur between two tributaries of 

 the Columbia River, namely, Kicking Horse River on the south and 

 Blaeberry Creek on the north. The summit of Mount Marpole 

 [2022] is a dark grey compact limestone, which weathers to a pale 

 brown colour and shows on a polished surface numerous small 

 spherical bodies, of a yellowish-brown colour, often with a greyer 

 central spot, which have some resemblance to the grains of aa 

 oolite, but weather out more quickly than the rest of the rock. 

 The matrix under the microscope is formed of calcite grains, 

 perhaps slightly dolomitic, somewhat variable in size and shape, 

 and enclosing a number of rather oval bodies about "05 inch in 

 longer diameter, commonly composed of an outer shell of grains 

 (diameter about '001 inch) with an approach to radial arrangement, 

 and a core of smaller grains and granules, with a little interstitial 

 brown colouring (? bituminous). Here and there we find a grain, 

 neither composite nor so large, suggesting, but not conclusively, an 

 organic origin. The rock seems to have undergone a considerable 

 amount of mineral, followed possibly by some mechanical change. 

 The summit of Mount Kerr [2023] is a very similar rock, but with 

 rather smaller and paler-coloured spots, which under the micro- 

 scope are seen to be approximately spherical and composed of 

 grains of calcite, outlined, and even faintly tinted, by brownish 

 material, embedded in clear granular calcite, much of the same 

 size, a little dolomitic, and showing a slight bending of the cleavage 

 planes, indicative of strain. Probably both these rocks are somewhat 



