10 
MUSEUM BULLETIN NO. 22. 
The identity of these formations was further confirmed by 
finding the greywacke intersected at one point by a 4-inch quartz- 
ite dyke similar to that shown in the accompanying illustra- 
tion. It has already been stated that dykes of this unusual 
nature have been found only in the middle members of the Bruce 
series and are regarded as an especially effective identification 
mark. On these grounds the formations in McGregor bay are 
regarded as Bruce series. 
In lithological appearance some of these rocks differ con- 
siderably from typical Bruce Series rocks found in less disturbed 
areas north of Lake Huron, but this is the result of metamorphism. 
The limestone has been partly converted into a lime-silicate 
rock and the greywacke is unusually dark and crystalline. In 
spite of these alterations, however, the original lithological 
characteristics persist strongly. 
A similar though much less complete succession was found 
at the upper end of Killarney bay. These rocks are best exposed 
on some rocky islets in the constricted tip of the bay. The 
dark corrugated Espanola greywacke is the chief formation 
exposed, though there is also some limestone interbedded with 
greywacke, and some of the conglomerate. All are intensely 
metamorphosed. Had it been necessary to compare them directly 
with the little metamorphosed members of the Bruce series 
in the northern part of the north shore district, e.g. at Bruce 
Mines or Whiskey lake, some uncertainty might have existed; 
but their similarity to the metamorphosed varieties in McGregor 
bay is unequivocal. 
Their relations to the Killarney granite, which extends 
along the south shore of Killarney bay, are equally positive. In 
the grassy southward-pointing tip of the bay the Espanola 
greywacke is in immediate contact with the granite, the latter 
being intrusive. In the same vicinity the granite alongshore 
contains numerous highly crystalline xenoliths of material 
which can be recognized as Espanola greywacke. In the writer’s 
opinion the sediments described certainly belong to the Bruce 
series. The granite intrusive in them is consequently younger 
than the Bruce series. 
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