Abstract

The Fort Grey silcrete near East London was reported in the earlier part of this century to contain Tertiary macro-plant fossils. The scarcity of evidence concerning the age and palaeoenvironments of weathering profile silcretes in the southern Cape prompted a reinvestigation of the site. The silicified gymnospermous wood is now assigned to Permo-Triassic genera in the Araucarioxylon/Dadoxylon and Podocarpoxylon/Mesembrioxylon groups described from India and Germany, and is not comparable to extant Tertiary forms as previously indicated. It also lacks the high Ti signature of the host silcrete. The fossil wood was evidently reworked from Permo-Triassic Beaufort strata and incorporated in Tertiary fluvial debris-flow deposits which were subsequently silcretized. The Fort Grey silcrete is typical of other southern Cape non fossil-bearing silcretes in terms of geological context, composition, texture, and high titanium signature. Since the fossil wood was reworked from older (Beaufort) strata, no useful inferences concerning the age of the silcrete can be drawn.

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