Landforms of British Columbia 1976 - Department of Geography

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high total relief and the massive boldness of the mountains provide some striking
mountain scenery. Strongly glaciated valleys which were subsequenly blocked by
glacial debris contain the basins of Bowon, Isaac, Lanezi, Hobson, Quesnel, Azure,
and Clearwater Lakes.
The Cariboo Mountains arc composed of sedimentary rocks and metamorphased
sedimentary rocks of Proterozoic and Lower Cambrian age. Although some
limestone is present, the principal rock type is quart&e in members of great thickness.
The rocks are folded about northwesterly striking axes into overturned folds
which in tom may be faulted parallel to their strike. The resistant quart&es to a
large degree influence the topographic forms developed. In the Clearwater area
“the character and structure of the underlying formations have noticeably affected
the configuration of the present surface. On the upland surface where underlain
by the metamorphic series the peaks arc sharp and the ridges continuous, where
underlaG” by granite the peaks are more massive and rounded and the ridges irregula
or radiating from a central mass.“*
The Cariboo Mountains comprise a number of longitudinal ranges trending
northwestward parallel to the strike of the underlying sedimentary rocks. Individual
mountains and mountain ranges rise to high serrate peaks of heights to
11,750 feet that are glacially sculptured and are separated by steep-walled glaciated
valleys that commonly form a trellis pattern controlled by the underlying bedrock.
The axis of the mountains lies to the east of Isaac Lake and mns southeastward
through the Premier Group.
The mountains were intensely glaciated, and peaks higher than 8,000 feet
projected through the Pleistocene ice-cap as nunataks which were subjected to
intense frost act:on and cirqw attack. There are some rounded summits and ridges
below 7.000 and 7,500 feet, but intense late-stag? cirqw glaciation on the northern
and northeastern slopes has produced many sharp peaks and sawtooth ridges which
characteristically combine gentler southerly and southwesterly slopes with steep
and abrupt northerly and northeasterly slopes. The intenselv ~- &xi&d trunk vallevs ,~
exhibit G-shaped piofiles, while trib&ary valleys are hanging in relation to them
(a%? Plate xxvIIIc).
[Reference: Sutherland Brown, A,, “Geology of the Cariboo River Area,”
B.C. Dept. of ,%4&w, Bull. No. 47, 1963.1
[Photographs: B.C. 387:65; B.C. 482:59; B.C. 487:62, 86; B.C. 765:
37, 58.1
The Monashee Mountains (see Plate XXIXA) occupy a northerly trending xca
250 miles long and for the most part 25 to 30 miles wide, lying between the Selkirk
Mountains on the east and the Cariboq Mountains and the Shuswap and Okanagan
HiGhlands on the west. The Monashee Mountains are widest at their southern end
between the Kettle and Columbia Rivers, a width of 55 miles. The boundaT with
the Selkirk Mountains, southward from Boat Encampment, is along the Colombia
River-Arrow Lakes valley.
The mountains comprise a number of individual ranges which have a northerly
to northeasterly trend south of latitude 50 degrees 30 minutes, but which swing to
a northwesterly trend farther north. This northwesterly trend is parallel to the
bounding Columbia River as far north as Goldstream North of Goldstream the
boundaries of the Monashee Mountains-namely, the North Thompson and Al-