Professor Bonney — Specimens from the Canadian Rockies. 295 



A specimen from a "washout beneath Forbes," at the junction 

 of the stream from the Freshfield Glacier with the valley from Bush 

 Pass, which runs ultimately into the Saskatchewan Eiver, is 

 a black cherty-looking rock, harder than the knife (insoluble in 

 HCl, but with faint traces of Ca C O3). This, under the microscope, 

 exhibits rather more minute granules and rhombs of a carbonate 

 (probably dolomite) than I should have anticipated; its general 

 colour being a very pale brown. The slice is crowded with small 

 clear organisms, about '005 inch in length, sometimes cylindrical, 

 which on examination with a high power prove to be siliceous. 

 The material is occasionally doubtfully colloid, more often of minute 

 crystalline granules, with occasional local replacement by calcite 

 or dolomite. Believing these to be sponge spicules, I submitted the 

 slice to Dr. G. J. Hinde, F.R.S., to whom I am indebted for the 

 following note : " These are rod-like bodies, showing traces of an 

 axial canal, which I feel certain are sponge spicules, and I should 

 also refer the confused mass of fragmentary rods to spicules, but 

 they are now so much altered that it is impossible to recognize if 

 any of them belong to lithistids" [I had suggested the possibility]. 

 He adds: "I have a slice of chert or cherty limestone from the 

 Durness Limestone of Sutherland which is not unlike your section, 

 but the spicules are more distinct and the rhombs of calcite or 

 dolomite less crowded than in the Canadian rock." The slice is 

 traversed by wavy dark-brown lines (? infiltrated cracks). 



The specimen from a peak south-east of Mount Lyell and west 

 of Mount Sullivan, at the head of the Valley of the Lakes (which 

 drains to the North Fork of the Saskatchewan), is a calcareous 

 conglomerate (Ca C O3, no Mg 0), consisting of rather flat, subangular 

 to rounded fragments, none exceeding '75 inch, of a pale grey 

 compact limestone in a yellowish calcareous matrix. Examination 

 with the microscope shows the fragments to be varieties of a limestone, 

 generally slightly dirty in aspect, occasionally a little speckled with 

 a dark brown ( ? bituminous) material, and crowded with minute 

 fragments of organisms (not to be identified with certainty) and 

 small round grey spots (about -0025 inch in diameter), probably 

 oolitic. There are also a few small gi-ains of quartz. The matrix 

 is more or less stained with limonite, contains many fragments of 

 organisms, similar but larger ; some showing traces of prismatic 

 structure, and probably molluscan ; some perhaps Brachiopods ; 

 some also possibly calcareous sponge spicules. 



Mount Forbes (about 12,000 feet) is also to the south-east of 

 Mount Lyell, but to the south of Mount Sullivan. A specimen 

 from near the summit is a dark limestone, containing Mg as well 

 as Ca 0, not unlike some British Carboniferous limestones. 



Mount Howse (about 10,800 feet) is in the same district, but to 

 the E.S-E. of the last peak, and on the watershed, where it suddenly 

 changes from a N.N.W. direction to a south-west one. The summit 

 is a compact darkish grey limestone (mostly Ca C O3, with a little 

 Mg C Os and a blackish residue after solution in H CI) with one 

 or two small white enclosures, and a few thin veins of calcite, 



