Tafoni show postglacial and modern wind azimuths that are similar at Bunger Hills

Abstract

The directions of strong winds are important for the distribution of marine salt spray, rock weathering, lake chemistry and the distribution of vegetation in Bunger Hills, a coastal ice-free oasis in East Antarctica. Present-day strong winds (> 10 m s−1) dominantly blow from 118 ± 21 degrees true (°T; ± 1 SD). Orientated tafoni (weathering pits) might form in bedrock surfaces by salt and ice crystallization, thermal stress and saltating sand particles, recording the orientation of a strongly directional wind field since the last deglaciation, which commenced > 30 000 years ago. The orientations of these tafoni, at 101 ± 18°T for 686 measurements at 28 sites, are indistinguishable from the direction of modern-day strong winds (> 10 m s−1), indicating that the orientation of the slope of the ice sheet has been stable throughout the last 10 000 years during the Holocene.

Spatial distribution of birds and terrestrial plants in Bunger Hills

“…The wind rose for Bunger Hills (Fig. 1) (Gore & Leishman 2020b) shows that winds prevail from the east–south-east, but that some winds also blow from the west–north-west. Gore & Leishman (2020b) discussed how strong winds blow from the east–south-east, whereas those blowing from the west–north-west are gentler.…”

“…1) (Gore & Leishman 2020b) shows that winds prevail from the east-south-east, but that some winds also blow from the west-north-west. Gore & Leishman (2020b) discussed how strong winds blow from the east-south-east, whereas those blowing from the west-north-west are gentler. This is important for the distribution of marine-derived salt spray downwind from marine inlets during the summer months, the types of salts and their distribution (Gore & Leishman 2020a).…”

“…Two systematic investigations of the biology of Bunger Hills (Leishman & Gore in 1995–96, Gibson in 2000) found that terrestrial flora was limited to algae, fungi, mosses and lichens, and terrestrial fauna was limited to birds and invertebrates, with occasional visits by seals. Lichens were more abundant near meltwater and surface streams in the south of the area close to the Apfel Glacier margin, and they were rarer in the areas in the north and west, possibly because of increased soil salinity created by aerosols from marine inlets and salt lakes (Gibson 2000, Gore & Leishman 2020a, 2020b). However, because not all of the land area of southern Bunger Hills, and particularly the areas upwind of the marine inlets, was surveyed, it was not clear whether or not salinity was the dominant control on the distribution of lichens across Bunger Hills.…”

Postglacial evolution of marine and lacustrine water bodies in Bunger Hills

“…However, the diatom record from Izvilistaja Inlet shows marine conditions until 2.2 ± 0.2 ka bp , which postdates a proposed mid-Holocene sea level high stand. Marine diatom frustules in the Algae Lake record are not restricted to a specific period during the Holocene and could be from aeolian supply from Cacapon Inlet, since strong winds transported sea spray across the adjacent land areas (Gore & Leishman 2020).…”

Salt, sediments and weathering environments in Bunger Hills

“…The area of both is similar, with southern Bunger Hills at 300 km 2 compared with Vestfold Hills at 400 km 2 (these values are approximate, depending on whether or not lakes and marine inlets are included and where the ice margin is plotted). Both have almost unidirectional strong winds, which have persisted for extended durations back into the Holocene and created orientated tafoni (weathering pits) in the bedrock in places (Pickard 1982, Gore & Leishman 2020). Given these similarities in geology, geomorphology and Quaternary history, it is probable that their terrestrial environments are also similar.…”