Soil and permafrost in the Ross Sea region of Antarctica: stable or dynamic?

M R Balks,T A O’Neill

doi:10.18172/cig.2923

Abstract

Soils in the Ross Sea Region of Antarctica generally comprise a surface desert pavement and a seasonally thawed active layer over permafrost. Most soils are formed on regolith such as glacial till or colluvium. Mean annual air temperatures range from -18°C to -24°C with low precipitation. The active layer ranges in depth from minimal in higher altitude, colder sites, to near 1 m deep at warmer coastal sites in the northern part of the region. Underlying permafrost may be ice-cemented, or dry with no ice cement. In some areas ice-cored moraine occurs where there is a large body of ice within the subsoil permafrost. Two examples of active gully/fan -forming events, one at Cape Evans and one at Lake Vanda are described. At the Cape Evans event water from a small lake thawed and came into contact with the ice in the underlying patterned ground ice-wedge causing the ice-wedge to melt and extensive gully erosion to occur. A fan-building event near Lake Vanda in the Wright Valley resulted in erosive and depositional features covering a horizontal distance of about 3 km and an altitudinal range of about 1400 m. Such occasional events, can be attributed to warmer than average summers, and were first described in the Ross Sea Region in the 1970s. The Cape Evans and Lake Vanda events are examples of active, rapid, landscape processes and show that landscapes are not as static as is often assumed.

Highlights

An understanding of Antarctic soils and the underlying permafrost is important to predict impacts of human activities or environmental changes, such as warming, on the soil and on geomorphological processes
The soils and landscapes of the Ross Sea Region are generally thought of as stable (Denton et al, 1993), with soil development progressing only slowly (Campbell and Claridge, 1987), in this paper we explore some examples of rapid, active, landscape processes occurring occasionally
The McMurdo Dry Valleys (MDVs) landscape has been considered stable over periods extending to millions of years (Denton et al, 1993; Marchant and Head, 2007) at higher altitudes where soil temperatures remain below 0°C slowing weathering and geomorphic processes

Summary

Introduction

An understanding of Antarctic soils and the underlying permafrost is important to predict impacts of human activities or environmental changes, such as warming, on the soil and on geomorphological processes. Soils in the MDVs and the wider Ross Sea Region are the most extensive (about 6 700 km2, Bockheim, 2015a), and most studied area of Antarctic soils (Campbell and Claridge, 1987; Campbell et al., 1998a; Bockheim and McLeod, 2015). They are often described as “cold desert” soils, reflecting their cold, arid, climate.

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