GEOLOGY 199 
of moderately regular size, cemented together by interstitial 
silica. They are very distinctly bedded in thick and thin beds, 
and the surfaces of the beds are often covered with beautiful 
ripple-markings. The heavier beds also often show distinct 
false bedding. They are usually in a more or less inclined atti- 
tude, but they were nowhere seen to be very much crumpled or 
squeezed into minute folds. Their total thickness was not 
determined.' 
' These quartzites were first noted by Dr. Bell from Marble 
island, and although this island was not examined by the writer, 
rocks of undoubtedly similar character to those described by Dr. 
Bell, were seen in many places along the shore, and conse- 
quently the name is here retained.' 
' In one place near the cache on the west side of Hudson bay, 
a thickness of sixty feet of this quartzite, in a nearly vertical 
attitude, was seen almost in contact with the Laurentian gneiss, 
there being but a narrow, drift-filled gap between the two. This 
would indicate either the existence of a fault, or that here the 
quartzites are the base of the Huronian, or that the gneiss repre- 
sents an eruptive rock which has risen through or into the 
Huronian subsequent to the deposition of the quartzite.' 
' Dark-green eruptive rocks, chiefly diabases, often very much 
squeezed and altered, are largely developed in the Huronian, 
composing a considerable proportion of the rocks of this system. 
On the west coast of Hudson bay these rocks are cut by many 
veins of white quartz, highly charged with iron and copper- 
pyrite.' 
' Associated with the massive diabases, and often indistin- 
guishable from them except on close examination, are many beds 
of fine-grained, often schistose graywacke, or greenish quartzite, 
which appear to have been caught up in, or surrounded by the 
eruptive rocks.' 
