Frozen ground phenomena in the vicinity of Terra Nova Bay, Northern Victoria Land, Antarctica: A preliminary report

Frozen ground phenomena in the Northern Foothills, Northern Victoria Land, Antarctica, include large-scale polygons, 15-20 m in diameter, and small fr ost mounds, 1-5 m high. The polygons are most widespread on terrain formed upon Younger Drift and are usually surrounded by interpolygon furrows or tr oughs, 10-30 cm deep and 10-100 cm wide. The troughs contain shallow wedges of sandy gravel (sand wedges) near the surface but excavations into underl ying permafrost indicate that small ice wedges or ice veins are locally pre sent. Field and anecdotal evidence suggest that thermal contraction crackin g is active under today's climate. Frost mounds occur in association with a number of perennially Frozen lakes in the region. In most cases they appea r related to Frost and icing blister activity caused by the episodic inject ion of free water from below. The debris-covered nature of the centre of En igma Lake is best explained in terms of basal ice accretion beneath the lak e-ice cover.