540

Site number:

540

Authors:

IBC, GGC

Date recorded:

1988/01/12

Reason Sampled:

Soil weathering examination

Description:

On a high dolerite surface above and to the Southwest of the Towle Valley, approximately 8km to the southwest of the Towle Glacier; an undulating largely snow-covered bouldery surface formed by earlier ice over-riding; the site is on the edge of a dolerite escarpment in a crack between fractured dolerite columns

Altitude:

1700 m

Aspect:

6o

Slope:

0 °

Climate

Soil climate zone:

Coastal Mountain, xerous to subxerous

Estimated mean annual temperature:

-29 °C

Frozen ground depth:

35 > cm

Frozen type:

Dry-frozen

Frozen comment:

>35cm

Geology

Geological setting:

Towle Valley is formed almost entirely in dolerite; the higher dissected plateau like surfaces above the Towle Valley have been exposed by ice sheet retreat; the extensive patchy snow cover may have restricted development of prolonged weathering; bedrock weathering takes place through joint plane disaggregation aided by wedging processes

Patterned ground:

Nil

Surface weathering or surface features:

Dolerite is coarse grained, weakly to moderately stained with surface disaggregation; soil material accumulating in joint planes forms wedges which slowly pry boulders apart as part of freeze and thaw processes

Soil

Soil parent material:

Fragmental dolerite in a joint plane crack

Previous disturbance:

Nil

Soil weathering stage:

6 4 (Campbell & Claridge 1975)

Soil moisture status:

Some surface snow cover but no present thawing

Biological activity:

Lichens are plentiful