Issues

Desiccation cracks in Middle Devonian rhythmic lacustrine sediments of Rousay Flagstone, West Kirbest, island of Westray, Orkney. The mud cracks here represent a temporary dry period within a lake bed where polygons are 25 – 30cm across and crack infills have been dolomitized, providing a colour contrast, enhanced by the presence of microbialites. Image courtesy of Dr David Leather, reproduced with permission.