Within the map area the Eureka Thrust is mar-
ked by sheared ultramafic rocks and serpentinite.
Black phyllite, siltite and minor sandstone and
limestone of the Triassic and Lower Jurassic of the
Quesnel Terrane are locally in fault contact with the
grit and pelite of the Barkerville Terrane where rec-
ognizable Slide Mountain Terrane rocks are absent.

Dans la région cartographique, le chevauchement d’Eureka
se caractérise par la présence de roches ultramafiques cisail-
lées et de serpentinite. Par endroits, de la phyllade noire, de
l’aleurolite et de faibles quantités de grés et de calcaire du Trias
et du Jurassique inférieur du terrain de Quesnel ont été mis
en contact avec le sable grossier et la pélite du terrain de Barker-
ville, la ou l’on ne reconnait aucune roche du terrain de Slide

Mountain.

ROCKS OF THE CARIBOO TERRANE

The Cariboo Terrane, bound on the west by the Pleas-
ant Valley Thrust and the Barkerville Terrane, is under-
lain by an unknown basement and is terminated upwards
by the Pundata Thrust and the tectonically emplaced Slide
Mountain Terrane. The Cariboo Terrane extends south
of the map area to Azure Lake, east to the Rocky Moun-
tain Trench and north to Macleod Lake. Its strata corre-
late with rocks of the Cassiar Mountains (Mansy and
Gabrielse, 1978).

Stratigraphic nomenclature for rocks of this terrane
is retained from earlier work with the addition of the Alex
Allan Formation. The status and definitions of some of
the units are changed. The Black Stuart is elevated to
group status and the Greenberry limestone member of
the Guyet Formation is defined as a formation (Green-
berry Formation). The type areas of the Cunningham,
Yankee Belle, Yanks Peak and Midas formations of the
Cariboo Group are abandoned and suggested instead to
be the reference sections described by Campbell et al.
(1973).

Stratified rocks

Introduction

The sequence of rocks ranges from Upper Hadrynian to
Middle Pennsylvanian and possibly Permo-Triassic
(Table 1). The lowest member of the section is the Kaza
Group (Sutherland Brown, 1957,1963; Campbell et al.,
1973). Overlying the Kaza Group with gradational con-
formity is the Cariboo Group, which ranges from Upper
Hadrynian to Cambrian.

The Ordovician to Mississippian Black Stuart Group
unconformably overlies the Kaza and Cariboo groups.
The Mississippian Greenberry Formation overlies the
Waverly and Guyet formations of the Black Stuart
Group. Since Johnston and Uglow (1926) first described
them the rocks of the Guyet, Greenberry and Antler for-
mations have been included in the Slide Mountain Series
or Group (see Table 2). This report proposes to remove
the Guyet and Greenberry formations from the Slide

' This creek will be informally called Separation Creek throughout this
report.

Mountain Group and to include them in the Black Stuart
Group with which they intertongue and overlie.

Kaza Group

The type section of the Kaza Group was described by
Sutherland Brown (1963, p. 13-19) from Bowron Lake
Park where he estimated the thickness to be approximate-
ly 3940 m. The base is not exposed. Predominant rock
types are brown weathering feldspathic and micaceous
quartzite, silver-green phyllite and schist and schistose
granule conglomerate. The quartzite is thick bedded
(3 m), forming 60 to 90 m thick units relatively free of
phyllite.

Within the field area, the Kaza Group coarse grained,
poorly sorted feldspathic, micaceous quartzite (grit) is
mapped in one locality; near the mouth of the first large
south-flowing tributary of Little River.! The exposure is
too poor to warrant significant lithological or stratigra-
phical descriptions, for which reference can be made to
Sutherland Brown (1963), Murphy and Rees (1983) and
Pell and Simony (1984).

Cariboo Group
Introduction

The Cariboo Group, which conformably overlies the
Kaza Group on a gradational contact, has a long history
of re-interpretation after being initially introduced by
Bowman (1889) as the Cariboo Series. Within this paper,
the evolution of Cariboo Group stratigraphy follows the
interpretation of Young (1969), Mansy (1970) and Camp-
bell et al. (1973), and its historical evolution is outlined
in Table 2 (in pocket).

The Cariboo Group is subdivided into seven forma-
tions which are from oldest to youngest: Isaac, Cunning-
ham, Yankee Belle, Yanks Peak, Midas, Mural and
Dome Creek. Within the described area the group is thick-
est at Kimball Mountain where it attains at least 2500 m.
Elsewhere it is thinner, but thickness variations are poorly
understood due to complexities of structure, and erosion
below an Ordovician unconformity.

Contacts within the group are gradational or con-
formable. For descriptions of the group’s formations in