30 Canadian Record of Science. 
rocks microscopically describes them as more or less al- 
tered diabases. 
The sedimentary rocks may be considered under two 
divisions; the upper in which the argillites and shales 
largely preponderate, and the lower consisting almost 
entirely of cherts and other siliceous rocks. In both of these 
divisions, between which no sharp line of demarcation 
exists, developments of calcareous and dolomitic areas are 
not untrequent. A characteristic of the upper division 
rocks consists in their generally carbonaceous character and 
the dark colour resulting therefrom. 
The cherty rocks of the lower division present many 
interesting features. In general appearance they are ex- 
tremely varied both in colour and grain, opaque browns 
and reds being the colours most usually presented. Milky 
whites and dark black also occur, and dark greens have 
been met with, which, when speckled with bright red spots 
constitute a very ornamental stone. 
In grain they vary between 4 compact flinty presentation 
with conchoidal fracture, in which no trace of their original 
nature can be seen by the unaided eye, to distinct sandstones 
whose fragmental nature is plainly brought out on weathered 
surfaces, the grains having been weathered out leaving a 
projecting reticulation of harder, less alterable material. 
The sandy grains are rounded and measure from 0:05 
inch in diameter and less. At times the above described 
feature is reversed. The cementing material originally 
surrounding the grain, apparently an earthy carbonate, is 
seen to have been removed by weathering, leaving the 
grains standing out. 
Brown oxides form a very constant constituent of all these 
rocks, to which is doubtless due their generally red and 
sometimes rusty appearance. This material also occurs in 
the form of magnetite to such an extent at places as to 
almost rank the beds as iron ores. Two spevimens of this 
variety were analysed in the laboratory of the Geological 
Survey, and gave respectively 39°74 per cent. and 45°57 
