Enk. Clarkson et al., PALEOECOLOGY OF THE VISEAN OF EAST KIRKTON, WEST-LOTHIAN, SCOTLAND, Transactions of the Royal Society of Edinburgh. Earth sciences, 84, 1994, pp. 417-425
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.