Fig. 3From: The swimming trace Undichna from the latest Devonian Hangenberg Sandstone equivalent of MoroccoPhoto of the outcrop with some vegetation after a reasonably rainy winter. Note the thin-bedded alternations of siltstone and fine-grained sandstones, which weather differentially relative to one another. Bed-thickness is likely due to variations in clay content, which, in turn, is probably controlled by variations in sea-level and clastic input. The Undichna described here is from the thicker bed marked by the arrow, which runs obliquely down the slopes on both sides of the arrowBack to article page