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ridges north of the Mesilinka for about 4 miles back from the river. Near
the east border of the map-area, these rocks are in fault contact against
highly metamorphosed and granitized rocks of the Wolverine complex, here
thought to be altered Tenakihi group strata. About 8 miles west of the
east boundary of the map-area, chloritic slates and phyllites are faulted
against more highly metamorphosed Wolverine complex rocks, which in
this place are considered to have been originally Ingenika group beds.

Rocks Between Blackpine Lake and Chase M ountain

_ In the through valley leading north from Blackpine Lake to Swannell
River, Ingenika group rocks are represented by long ridges of massive to
poorly bedded, blue-grey, crystalline limestone, with a few scattered expos-
ures of quartzitic conglomerate and quartz-chlorite schist. On the east side
of Swannell River Valley, southwest of Chase Mountain, limestone outcrops
in large bluffs, ridges, and bare hills, and is the only rock type observed
within an area 2 miles wide by 8 miles long, although some float of mica-
ceous and chloritic rocks was found. Owing to the massive nature of most of
the limestone, the structure is obscure, but it would appear that unless there
is important repetition of beds by faulting, the total stratigraphic thickness
in which limestone is the dominant rock is of the order of 6,500 feet.
Uniform bodies of limestone at least 300 feet thick, with no intercalation of
other rock types, are exposed on large broken bluffs. Most of the limestone
in this area is light blue-grey, relatively non-crystalline, massive, or vaguely
bedded. Some beds are strongly oolitic. Bands, which may be parallel with
the bedding, and irregular areas, up to 500 fect across, of light grey or
creamy buff weathering recrystallized limestone give the rock a variegated
appearance on a large scale. In places the limestone is strongly brecciated ;
angular fragments of uniform, fine-grained limestone up to 4 inches in
diameter are embedded in a creamy buff or reddish brown, coarsely crystal-
line carbonate matrix. In some exposures the whole rock is composed of
semi-rounded fragments of blue-grey fine-grained limestone up to 4 inch
in diameter, fairly well sized, and closely packed in a light brown crystalline
carbonate groundmass; such rocks may be in part conglomerates, with the
fragments transported a considerable distance from their source. In other
places the brecciation has clearly involved only slight rock movement. In
these places the brecciation is not confined to well-defined bands, and bears
no obvious relation to the major tectonic structures of the rocks in the
district. In some of the brecciated areas, the recognizable fragments of
original rock do not compose more than about one-quarter of the rock
volume; the remainder consists of brownish, reddish, and cream-coloured,
crystalline carbonate material. The carbonate occurs in characteristic con-
centric bands of crystals oriented perpendicularly to the surface of the
fragments they surround; variations in texture and colour of successive
bands give a conspicuous ‘cockade’ appearance to the rock. Bands com-
posed of radiating, prismatic crystals up to 3 inches long were noted. In
all the breccias the fragments have sharp outlines.

Interbedded with the massive limestones and limestone breccias of the
western part of this area are relatively minor amounts of grey, brown,
massive to well-banded, slaty siltstone, containing considerable pyrite in
some beds; and green, chlorite-sericite phyllite. One exposure of ivory-
coloured sericitic limestone, with thin partings of chloritic slate, was noted.