12 
MUSEUM BULLETIN NO. 8. 
At the bottom of the lower series is a feldspathic quartzite 
1,000 feet thick, the beise of which is a conglomerate, probably 
not over 75 feet thick, composed of granite, greenstone, and other 
boulders and pebbles, including a few of slate, enclosed in an 
arkose matrix. This conglomerate is usually separated from 
the underlying granite by from a few inches to several feet of 
arkose or disintegrated granite, which grades imperceptibly 
downward, in from 4 to 18 inches, into unaltered granite. Occas- 
ionally fissures filled with arkose can be traced downward into 
the granite. The conglomerate and arkose at the base of this 
lower quartzite clearly rest unconformably upon a decayed 
granite surface as in the Blind River and Bruce areas. The 
main upper part of the formation is a coarse-grained, feldspathic, 
white quartzite. Above this, in sharp and faintly unconformable 
contact, is 100-125 feet of conglomerate. The lower part con- 
sists of large boulders, principally of granite, embedded in arkose, 
but toward the top the matrix grows finer and more like a grey- 
wacke while the included fragments diminish in number and size. 
No good exposure was found showing the succession immediately 
above this second conglomerate but it is believed to grade 
upward into a greywacke only a few feet thick. This gives 
place conformably to 150 feet of grey limestone which carries 
thin siliceous layers in its upper and lower portions but is nearly 
pure in its main middle portion. The limestone passes conform- 
ably up into 350 feet of a dull grey, well stratified and somewhat 
calcareous greywacke, interbedded in places with more quartzitic 
beds. The greywacke is succeeded conformably by 50-75 
feet of a very Impu re, red-weathering limestone in beds from 18 
inches to several feet thick alternating with layers of siliceous 
greywacke 4 feet or more in thickness. 
The red-weathering limestone and the underlying greywacke 
present several remarkable features that suggest the existence of 
suba6rial conditions during their deposition. The greywacke 
includes, about 40 feet above its base, a breccia made up solely 
of fragments of that formation and of limestone. The grey- 
wacke and the upper limestone are also intersected by numerous 
clearly defined dykes or fissures 6-15 inches wide, filled with 
coarse, impure quartzite or fine conglomerate. These quartzite 
