to explain the absence of quartzite between areas where
thicknesses can be up to 60 m. A simple southwest dis-
persion would require gradual diminishing of quartzite
to the southwest. This gradual diminishing is not the
picture presented in Figure 8.

Table 5. Yanks Peak Formation incomplete

stratigraphic section on Mount Kimball
(location; 52°55’40’”N, 121°3’02”W).

Thickness in metres
Unit Lithology Unit Above base

13 Quartzite, white, coarse grained to
fine granule conglomerate, coarsens
upsection, crossbeds in lower part
Um. ek ee. Sed os al vi 45 280

Interbedded micaceous quartzite,
grey, and well sorted white quartz-
ite, moderately coarse grained .... 2 235

tks
PO

1

ok.

Quartzite, white, moderately coarse
ee ee cas nin us 10 239

Interbedded slate, olive-green-

brown, silty, micaceous quartzite,

brown weathering grey, moderately

fine grained and well sorted quartz-

ite, light pink, medium grained;

"Oe CRS] CY el ag a 4 Des
Quartzite, olive and brown weather-

ing grey, micaceous, moderately
RCS cts ee oe 4 219

1

oO

ide)

(oe)

Quartzite, white, well sorted,
coarse- to granule-grained ....... 28 210

~N

Quartzite, grey, moderately fine
grained; slightly sericitic ........ 3 187

(op)

Sandstone, brown limonite
(CATE Ce eee ee er 02 184

Interbedded quartzites, light green,

well sorted, moderately fine and

olive grey, micaceous medium
ie ih. se ae d= 10 184

Conglomerate, white, granules of
rounded to subrounded clear quartz
with minor blue quartz .......... 1 174

on

b

wo

Interbedded quartzite, dark brown

weathering grey-brown, micaceous,

moderate to moderately fine

grained, poorly sorted, limonite,

slate, olive and minor quartzite,

white, medium grained; gradational

1 to 30 cm beds with 3 to 10 cm

es CONMION a a8 We Bw ow 90 173

DO

Quartzite, grey, micaceous, medium
grained: 15 to 50 cm beds ...... 30 83

Quartzite, white, medium grained . 53 53

—

Underlying beds: Yankee Belle
a Formation

Age and correlation. Campbell et al. (1973) considered
the Yanks Peak Formation to be of lowermost Cambrian
age and correlated it with the McNaughton Formation
of the Rocky Mountains directly to the east. No further
evidence on the age of the Yanks Peak Formation has
been obtained and the conclusion of Campbell et al. is
accepted here.

Midas Formation

The Midas Formation consists of slate, phyllite, siltite and
quartzite. It can be differentiated from the Yankee Belle
Formation in four ways: 1) the Midas Formation is not
known to have limestone members in its basal part as does
the Yankee Belle Formation; 2) the pelites of the Midas
Formation are generally greyer and more platy where not
metamorphosed to phyllite; 3) if present, the crossbedded
Vic Sandstone with its lamellae of heavy minerals is dis-
tinct from any lithology in the Yankee Belle Formation;
and 4) the Yankee Belle Formation coarsens upsection
to the Yanks Peak Formation whereas the Midas For-
mation fines upwards to the Mural Formation. Where
the Yanks Peak Formation quartzite is not present the
contact between the Yankee Belle Formation and Midas
Formation is difficult to define; however, in almost all
cases there is at least a lens of white fine- to medium-
grained quartzite at the horizon where the Yanks Peak
Formation is expected. In isolated small outcrops distinc-
tion between Midas and Yankee Belle formations is
uncertain.

Midas Formation has not been recognized north of
lower Pleasant Valley Creek though it underlies much of
the area to the south. The type locality of the Midas For-
mation is defined as the reference section described by
Campbell et al. (1973) from the Dome Creek area
(56°36’N, 121°01’W). The original type section defined
by Holland (1954) at Yanks Peak is recommended to be
abandoned. It does not contain the same unit of rocks
as those called Midas Formation east of the Pleasant
Valley Thrust. At the Dome Creek section the unit is
148 m thick and the thickness varies from 91 to 305 m
throughout the Cariboo Mountains (Campbell et al.,
1973). Thickness of the formation throughout the map
area varies from 40 to 250 m. North of Cariboo River, the
thickness is determined at two localities. The formation
is approximately 40 m thick with the base unexposed at
the junction of Pleasant Valley and Antler creeks, and
about 45 m thick at Loskey Creek. Thicknesses south of
Cariboo River can be determined for three localities. On
the hill 5 km southeast of Black Stuart Mountain, it is
approximately 50 m thick, bounded on top by archaeo-
cyathid-bearing Mural Formation limestone and at the
base by a thin quartzite lens assigned to the Yanks Peak
Formation. On Anderson Ridge,! poorly exposed Midas
Formation may attain 250 m in thickness. On the south
slopes of Kimball Ridge a partly covered succession is
approximately 130 m thick.

"Anderson Ridge is the east-trending ridge south of upper Kimball Creek and southwest of upper Connection Creek. This

name was used by Lang (1938).

17