Physiography and Glaciation

Table I SUBDIVISIONS SysTEMS AREAS = Primary Secondary Tertiary Quaternary Columbia | Mountains | Fraser Plateau | Nechako Plain | Nechako Francois Lake Nulki Hills Plateau Highlands ee Interior System |Southern Plateau) Interior Plateau | | Cheslatta Hills and Mountain fee een ee Sk area Tetachuck Hills

| Plateaux and

Entiako Plateau

| | Valleys — | Chedakuz Valley

Euchiniko Plateau

Interior Ranges | Fawnie Range

| Nechako Range

\— - - — —

Central Plateau | and Mountain | area |

graphically. Fraser Plateau is underlain mainly by Tertiary volcanic rocks whereas the Nechako Plateau is underlain mainly by pre-Tertiary volcanic, sedimentary, and granitic rocks. Nechako Plateau is more dissected than Fraser Plateau and is rougher in detail, with greater local relief.

The Nechako Plain, although extensively underlain by flat-lying volcanic rocks, more probably takes its relatively even surface from extensive erosion which truncated rocks of several ages, and from a deep covering of glacial till or silt and glacial lake clay (Armstrong, 1949, p. 8).

Francois Lake Highlands (see Pl. Il) is a good descriptive name and its further subdivision into groups of hills is topographically correct. These hills are in no way oriented into ranges of mountains although some are referred to as mountains. Most of these hills are less than 5,000 feet in elevation with less than 1,500 feet relief, and although some may rise abruptly, most rise

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