Trackway preservation in eolian sandstones from the Permian of Scotland

Despite the widespread conception of deserts as places almost barren of life, the geologic record shows that the tracks and traces of animals are often associated with desert deposits. The reluctance of some geologists to associate such tracks with eolian deposits has even led some to conclude that the tracks, and therefore the rocks, were formed under water. Eolian sandstones showing the tracks of vertebrate animals range from Carboniferous to Holocene in age and include such famous formations as the Coconino and Navajo sandstones of the United States, the Botucatu Sandstone of Brazil, and the Cave Sandstone of southern Africa. Three eolian sandstone formations from the Permian of Scotland have tracks believed to have been made by pelycosaurs, anomodonts, and pareiasaurs. A study of these formtions has helped in interpreting how such tracks in eolian sandstones were formed and preserved. Two of these formations occur in isolated basins in Dumfries and Galloway, where the tracks occur on the surface of very thin, clay-rich, silt laminae probably deposited following a storm or small-flood event. The tracks from a third formation in Grampian are closely associated with sheetflood deposits and contorted strata, both believed to indicate the presence of water. Sufficient water was therefore present in both areas to give the sand the degree of cohesion necessary for track formation and preservation.