Mudcracks
The next stop emphasises the hot and arid climate of the Devonian, which is quite different to the current Irish climate. Here polygonal cracks can be seen on the surface of a green siltstone unit. These are dessication cracks or mudcracks. Mudcracks form from the shrinkage and contraction of water-saturated, clay rich sediment due to dehydration as evaporation occurs. These features are preserved by the influx of later sediment which fill the cracks and cover the surface. The presence of mudcracks indicates that the sediment experienced quite rapid alteration between wet and dry conditions. This kind of environment with temporary puddles and shallow pools, alongside longer lasting river channels is typical of floodplains. A floodplain environment would also readily supply large volumes of sediment which could quickly cover the surface of the cracks and aid in preservation. 
