Wedge Structures in Southernmost Argentina (Rio Grande, Tierra del Fuego)

Abstract

[EN] Wedge-like structures occur in raised beach gravels near Rio Grande, eastern Tierra Del Fuego (latitude 53°50′S; longitude 67°5′W). They vary in dimension, being approximately 1.0–1.5 m deep and 0.3–0.8 m in apparent width. Some are closely spaced, while others are as much as 5.0–8.0 m apart. The infill is predominantly fine and coarse sand, together with silt, all of local provenance. There is little evidence of secondary infill. It is unclear whether these structures are soil wedges, sand wedges, or composite wedges. Their significance as regards the possible previous occurrence of perennially-frozen ground in the lowlands of Tierra del Fuego has yet to be determined.