Figure 43. Photomicrograph of silicified kamaenid or
halysisid algae from the Downey succession of the
Snowshoe Group on Sugar Creek. (GSC 191039)

He suggested that the fossils exclude a Precambrian age
and can be from any level of the Paleozoic, Late Cam-
brian and younger, though less likely Cambrian. The
Downey succession is correlated with the part of the Eagle
Bay Formation of southern British Columbia that in-
cludes the calcareous and volcanic rocks of Dixon Creek
(unit 3 of Preto et al., 1980; Preto, 1981) and the tuff
and agglomerate (unit 9 & 10 of Preto et al., 1980) that
outcrop along the Adams Lake road. In that these rocks
of the Eagle Bay Formation underlie the dated Missis-
sippian rocks of the Eagle Bay Formation, the Downey
succession is probably lower Paleozoic.

Bralco limestone

The Bralco limestone consists mainly of limestone, mar-
ble and minor phyllite. The limestone is similar to that
of the Mural and Cunningham formations of the Cari-
boo Terrane. The marble is similar to that of the Downey
succession but is purer carbonate. The only distinguish-
ing characteristic of the Bralco limestone is its strati-
graphic position above the Downey succession.

60

The Bralco limestone is confined to the belt parallel-
ing the Pleasant Valley Thrust from Summit Creek south-
eastward to Cariboo Lake and beyond the map area to
the north arm of Quesnel Lake. The limestone was pre-
viously mapped as part of the Cariboo Schists by
Bowman (1889), as part of the Barkerville Formation by
Johnston and Uglow (1926) and Lang (1938), as the
Midas Formation by Holland (1954), as the Isaac Forma-
tion by Campbell et al. (1973) and as the Cunningham
or Mural Formation by Struik (1981, 1982b). There is no
type section for the unit; a reference exposure is at the
headwaters of Penny Creek. Thickness of the carbonate
is highly variable, and is less than 100 m.

The Bralco limestone overlies the black siltite and
phyllite of the Downey succession along the length of its
exposure. Similar carbonate appears in outcrop areas of
the Downey succession in the northwestern part of the
map area.

The light to dark grey limestone and marble consists
of 0.2 to 2 mm calcite crystals and near Roundtop Moun-
tain contains up to 10% algal pellets up to 2 mm across.
The noncarbonate component is minor consisting mostly
of fine grained quartz and lesser heavy minerals. The car-
bonate is commonly laminated on a 1 to 3 cm scale.

In the vicinity of Penny Creek the Bralco limestone
appears to be thrust faulted with brown-grey phyllite, pos-
sibly an alteration of the Downey phyllite. Although this
phyllite is included in the Downey succession it may be
part of the Bralco limestone sequence. Part of the phyllite
resembles that of the Midas Formation on Roundtop
Mountain.

Age and correlation. The age of the Bralco limestone is
thought to be Paleozoic because pelletoidal limestone
(Fig. 44) found near Roundtop Mountain (GSC Loca-
lity C-102828 Lat. 52°55’14’’ Long. 121°20’3’’) contains
echinoderm fragments, as identified by B.L. Mamet. It
may correlate with the Tsinikin Limestone of the Eagle
Bay Formation.

within the Bralco marble of the Snowshoe Group near
Roundtop Mountain.