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MUSEUM BULLETIN NO. 8. 
The Unconformity Between the Lower and Upper Huronian Series. 
The relations of the upper to the lower Huronian series in 
Whiskey Lake area are well exemplified in a conspicuous bluff in 
the southwestern bay of Big lake. There the basal conglomerate 
of the upper series, dipping 15 degrees south, lies upon almost 
horizontal upper quartzite formation of the lower series. The 
actual contact along the face of the bluff is a sharply defined and 
somewhat wavy line cutting obliquely across the bedding planes 
of the quartzite. The conglomerate above contains a great 
variety of pebbles among which is a considerable number of 
quartzite and finely stratified greywacke evidently derived from 
the lower Huronian. While the granite and other pebbles 
foreign to the locality are well rounded and not large, some of 
those obtained from the sediments beneath are 2 feet in diameter 
and subangular. 
There are numerous exposures on Lauzon lake and Lake of 
the Mountains in Blind River area, of the same unconformity 
between the basal conglomerate of the upper series and the lower 
quartzite (Mississagi) formation of the lower series. The 
conglomerate contains a similar diversity of materials and the 
fragments derived from the underlying formations of the lower 
series are often large and imperfectly worn. No pebbles of 
limestone could be found although on the coast of Lake Huron 
west of Blind River, where the conglomerate overlies the lime- 
stone, it contains numerous limestone pebbles. It seems prob- 
able that the fragments of the lower Huronian series were not 
as resistant to erosion as the older, and thoroughly consolidated 
pre-Huronian rocks, and hence only pebbles of one or a few of the 
lower Huronian formations are found in the conglomerate above. 
The contact is gently irregular, but beyond this there is no per- 
ceptible discordance in any one locality between the beds of the 
upper and lower series. 
The same wavy, sharply defined line of contact, abundance 
of subangular to rounded pebbles of the underlying formation 
but dearth of other lower Huronian fragments, and lack of 
perceptible discordance characterizes the contact between the 
upper series conglomerate and the lower series limestone in lot 2, 
