Accumulation of drifted logs and other large plant debris in a Carboniferous fluvial channel at

Abstract

A fragment of transverse section through a fill of a great fluvial channel in coal-bearing deposits of the Mudstone Series (Westphalian A and B) is exposed at Czerwionka in Upper Silesia. The depositional environment of this series is interpreted as an extensive, plant covered, alluvial plain constructed by low-gradient suspended-load rivers. lntraformational conglomerate on the channel bottom is overlain by a thick (up to 6.5 m) layer of fine-grained sandstone with mass occurrence of coalified logs and other large plant debris. The fossil flora is dominated by Cordaites but other plants are also present. Most of the logs are filled with sand, which is often laminated. Long logs lie horizontally and are preferentially orientated transversally to the channel axis. The accumulation of large plant debris at Czerwionka was deposited in an active channel of a large river. Heavy, partly rotten and waterlogged logs were dragged as bedload along the bottom, successively trapped, and buried with sand.