Investigation of moraines in the Pearse Valley (Ian Wright)

Moraine lobes which flank the Pearse Valley slopes of the Kukri Kills were mapped in detail. The lobes average 250 to 300 metres in length with faces approximately 25 metres high and have wind-blown hollows giving the surface hummocky relief. Surface clasts show no evidence of imbrication or elongation.

These lobes are interpreted to result from at least two phases of alpine glaciation. Detailed mapping revealed that one lobe contains features possibly formed by delayed retreat during the second phase. This could possibly be interpreted as a third alpine glacial phase.

The alpine moraines can be distinguished from Robinson's (1978) "early Taylor" moraines present in the Pearse Valley by mineralogical composition. The "early Taylor" moraines contain plutonic clasts, specifically K-feldspar granites, which are absent from the alpine moraines.

Formation of patterned ground on the alpine moraine surfaces indicates they are ice-cored and Robinson (pers. comm.) has found matrix ice within the moraines. The shape of the moraines suggests plastic deformation of the matrix ice is presently occurring.

Further investigation in the Pearse Valley is needed to relate the chrono-stratigraphy and ice-flow directions of the "Taylor" glacial expansions to the alpine glacial phases, and also to the fluctuations in levels of Lakes House and Joyce.