PALEOECOLOGY OF THE VISEAN OF EAST KIRKTON, WEST-LOTHIAN, SCOTLAND

The Visean sequence at East Kirkton was deposited in a shallow lake, s et within a richly vegetated landscape formed of volcanic cones a few hundred metres high. There was little volcanic activity, however, whil e the lake existed, and the many tuff horizons within the sequence wer e washed in during weathering. The lake may have been generally cool, though of unusual water chemistry, as a result of which the spheruliti c East Kirkton Limestone precipitated. At times, however, water temper atures may have risen sharply through localised hot-spring activity; b oth factors deterred 'normal' aquatic life. The bulk of the preserved biota consists of plants (permineralisations and compressions) and dom inantly land-living animals, including the oldest terrestrial tetrapod s (amphibians and reptiliomorphs), large terrestrial-aquatic eurypteri ds, the first harvestman and rare millipedes. All these animals lived close to the lake, in a fire-prone forest dominated by gymnosperms and pteridosperms. At a late stage in the history of the lake, deposition of spherulitic limestones was replaced by black shales, bearing a 'st andard' Oil-Shale fish fauna, suggesting that the isolated lake had li nked with a larger fish-bearing water body. This is coupled with a shi ft to a lycopod-dominated flora and may indicate a climatic change to wetter conditions. Finally the lake silted up with tuff, ending an exi stence of only a few tens of thousands of years.