The section of Cunningham Formation on Kimball
Ridge (location; 52°55’10’’N, 121°00’10’’W) provides a
local reference and is not meant to replace the type section
(Table 3).

Age and correlation. No new information has been
gathered on the dating of the Cunningham Formation.
An upper Proterozoic age was assigned by Young (in
Campbell et al., 1973) and is accepted in this report. It
is correlated with the Espee Formation of northern British
Columbia (Mansy and Gabrielse, 1978).

Yankee Belle Formation

The Yankee Belle Formation consists of slate or phyllite,
quartzite, siltite, limestone and sandy limestone. Isolated
exposures of pelite, siltite or fine grained quartzite can
be confused with similar rocks of the Midas Formation
or parts of the Keithley succession of the Barkerville
Terrane. Yankee Belle Formation limestone has most of
the characteristics of Cunningham Formation limestone.
In more continuous exposures the gradation upsection
from interbedded limestone, quartzite, and pelite to domi-
nant pelite and siltite with lesser olive quartzite to white
quartzite and, near the top, to olive pelite is typical of
the Yankee Belle Formation.

The formation underlies much of the area southeast
of Cunningham Creek and east of the Pleasant Valley
Thrust. A small outcrop of the unit is exposed on Summit
Creek.

The type section of the Yankee Belle Formation is
defined as the reference section (908 m thick) described
by Young (in Campbell et al., 1973) in northern Cariboo
Mountains at the headwaters of Dome Creek. The origi-
nal type section from Yanks Peak described by Holland
(1954) is abandoned because it is not Yankee Belle For-
mation as presently used. Those rocks are part of the
Barkerville Terrane and have only remote, if any, affini-
ties to Yankee Belle of the Cariboo Terrane. A compo-
site section of Yankee Belle Formation on Kimball Ridge
has a thickness of approximately 1085 m, although Mansy
(1970) measured a similar composite section on Kimball
Ridge as being 600 m thick. Thicknesses in other parts
of the area are: approximately 150 m, 5 km southwest
of Black Stuart Mountain and 170 to 500 m in Round-
top Mountain area. The relationship of thickness varia-
tion to geographic position is complicated by east to west
thrusting (Fig. 6).

The lower contact of the Yankee Belle Formation is
conformable and gradational with the Cunningham
Formation. It is defined as the first occurrence of quart-
zite above the massive limestone of the Cunningham
Formation.

Limestone of the Yankee Belle Formation is grey to
greenish grey and may be white or light greenish cream
due to recrystallization to marble. It forms 1 to 25 m
members near the base, decreasing in frequency upsec-
tion from the Cunningham Formation contact. Though

Sed oral

BOWRON
LAKE
TWO SISTERS

MTN

S
Sut KIMBALL
& See baci

SARIBO0 RivER/

———

—-~~ —a— position of restored
thrusts as measured
from structure section
A-A'

contours in metres

° 6 2
KILOMETRES

Figure 6.
Formation.

Palinspastic isopach map of the Yankee Belle

the thickness of the Yankee Belle Formation varies con-
siderably, south of Cariboo River, everywhere its lower
half has interbedded limestone and phyllite or slate. North
of Cariboo River, limestone is not found in the Yankee
Belle Formation, but Summit Creek is the only place
where the base of the Yankee Belle Formation is known
with certainty. On the south slope of Roundtop Moun-
tain, Yankee Belle Formation quartzite and slate overlie
grey limestone, but whether the limestone is a basal
member of the Yankee Belle Formation or part of the
Cunningham Formation is not known. Sandy limestone
is found only on Kimball Ridge and 5 km southeast of
Black Stuart Mountain.

Pelletoidal limestone on Kimball Ridge has undergone
irregular neomorphism, producing patches of finely and
moderately fine crystalline calcite matrix surrounding 0.5
to 3 mm pellets. The pellets have very fine to finely
crystalline calcite in their cores. In thin section concen-
tric outlines of grey opaque material ring the centres. In
some cases radial crystal growth occurs between the