FROM NEAR LAKE AINSLIE, N. S. POOLE. 3-45 



and would represent but a small proportion of felspar. Thin 

 splinters of the material are with great difficulty fusible before 

 che blowpipe, becoming in fact only just, and no more, rounded on 

 the thinnest edges. This also would tend to show that the 

 amount of felspar present is but small. There is not, so far as 

 I am aware, any tixed ratio between the quartz and felspar 

 in what are commonly designated felsites. Hence the material 

 in question might by many, if not most, be referred to as felsite 

 — and possibly permi.ssively so. They exhibit an unmistakable 

 concentric structure. I am disposed to refer to them as " slightly 

 felspathic quartzose concretions." When next writing would 

 you kindly mention locality of occurrence, and I will then place 

 the same in our museum collection — duly crediting you with 

 the presentation. 



I remain. 



Yours faithfully, 



G. Chas. Hoffmann. 



The locality where these bombs were found is on the Gair- 

 lock mountain road, half a mile from the east shore of Lake 

 Ainslie, on the slope of the hillside within the loop which the 

 road makes opposite the entrance to the ravine and within a 

 stone's throw of the barite mine on the lands of Johnstone. 

 The barite veins occur in a reddish volcanic ash or quartz-felsite 

 and the bed of bombs appears to be at or about the contact of 

 the ash bed with a band of basic volcanic rocks. The limits of 

 the trap rocks are easily distinguished, as its beds are all dark 

 in color while that of the quai-tz-felsite varies throuo;h lioht 

 shades of yellow and pink to those of a reddish cast, weather- 

 ing even to whiteness with minute crystals of sanidine(0 

 sparkling on the faces of fracture. 



The deposit was very superficially exposed and where it 

 had been long subject to surface influences. It seemingly was 

 on edge, and apparently considerable excavation would be 

 required to lay bare the bed where it had not been disturbed 

 in order to establish the relation of the basic lava flows to the 

 highly silicious tuff to which evidently belongs the special 

 portion of the deposit containing the bombs, and a further 



