Abstract
Abstract. Longitudinal ice-surface structures in the Antarctic Ice Sheet can be traced continuously down-ice for distances of up to 1200 km. A map of the distribution of ~ 3600 of these features, compiled from satellite images, shows that they mirror the location of fast-flowing glaciers and ice streams that are dominated by basal sliding rates above tens of metres per annum and are strongly guided by subglacial topography. Longitudinal ice-surface structures dominate regions of converging flow, where ice flow is subject to non-coaxial strain and simple shear. They can be traced continuously through crevasse fields and through blue-ice areas, indicating that they represent the surface manifestation of a three-dimensional structure, interpreted as foliation. Flow lines are linear and undeformed for all major flow units described here in the Antarctic Ice Sheet except for the Kamb Ice Stream and the Institute and Möller Ice Stream areas, where areas of flow perturbation are evident. Parcels of ice along individual flow paths on the Lambert Glacier, Recovery Glacier, Byrd Glacier and Pine Island Glacier may reside in the glacier system for ~ 2500 to 18 500 years. Although it is unclear how long it takes for these features to form and decay, we infer that the major ice-flow configuration of the ice sheet may have remained largely unchanged for the last few hundred years, and possibly even longer. This conclusion has implications for our understanding of the long-term landscape evolution of Antarctica, including large-scale patterns of glacial erosion and deposition.
Highlights
– Hypothesis 1: they form as a result of lateral compression in topographic situations where glaciers flow from wide accumulation basins into a narrow tongue
The Moderate Resolution Imaging Spectroradiometer (MODIS) Mosaic of Antarctica (MOA) is a composite of 260 swaths comprised of both Terra and Aqua MODIS images acquired between 20 November 2003 and 29 February 2004
Longitudinal foliation can develop on glaciers in a number of situations, the most likely origin is from lateral compression and simple shear created by converging ice flow
Summary
Flow-parallel features on glaciers and ice sheets are commonly referred to in the literature as “flow stripes”, “flow bands”, “flowlines” or “streaklines” (Crabtree and Doake, 1980; Reynolds and Hambrey, 1988; Swithinbank et al, 1988; Casassa et al, 1991; Casassa and Brecher, 1993; Gudmundsson et al, 1998; Jacobel et al, 1993, 1999; Fahnestock et al, 2000; Hulbe and Fahnestock, 2004, 2007). Longitudinal ice-surface structures are commonly developed parallel to ice-flow direction along the margins of individual ice-flow units and are inferred to represent relict or contemporary flowlines within an ice sheet (Fahnestock et al, 2000). They are present both in accumulation areas of the ice sheet, where they are snow-covered and they are picked out by variations in surface topography, and in areas of surface ablation (blue-ice areas), where they represent the surface manifestation of the three-dimensional structure, longitudinal foliation (Fig. 3) (Hambrey and Dowdeswell, 1994).
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
