Abstract A major stratigraphical problem in the offshore Paleozoic of the Inner Moray Firth is the identification of the top of the Devonian Old Red Sandstone Group beneath the lithologically similar Permian Rotliegend Group. Wireline log criteria for a revised Old Red Group to Permian boundary are given for the Inner Moray Firth. Section lines drawn using these criteria and flattened on the overlying Triassic Smith Bank or Permian Kupferschiefer formations show a relatively thin development of Rotliegend with two depocentres. The underlying Devonian when flattened on the Eday Marl shows a systematic subcrop pattern. There is currently no exposed onshore Old Red to Rotliegend boundary, but the possibility remains that a Permian section is present in the ‘Upper Old Red Sandstone’ of Tarbat in Easter Ross. An exposed Permian–Devonian boundary is present in East Greenland and provides an analogue for the Inner Moray Firth.

Abstract The Late Devonian early tetrapods in East Greenland occur in the Celsius Bjerg Group. Key occurrences are located in a detailed stratigraphic section used here to interpret the sedimentary palaeoenvironments. The palaeoenvironment for the Britta Dal Formation (which contains both Ichthyostega and Acanthostega ) is reinterpreted. The Britta Dal Formation channels have flat bases, are poorly channelized, are of low sinuosity and are part of a very major distributory system that periodically experienced extreme flooding. The tetrapod fossils were recovered from an ephemeral system that was not permanently habitable in the immediate area. Plant megafossils are poorly preserved casts and impressions dominated by lycopsids and fern-like plants. The overbank siltstones are dominated by arid soil forming processes and comprise a spectacular sequence of vertisols. The 1174 m in situ Ichthyostega locality in Paralleldal was relocated and occurs just below the midpoint of the second megacycle in the Britta Dal Formation.

Abstract The Kačák Event is a late Eifelian (Mid-Devonian) episode of marine dysoxia/anoxia with associated extinctions. It has been widely recognized in the shelf seas that surrounded the Old Red Sandstone continent. It was contemporary with the lacustrine Orcadian Basin in Scotland. This basin contains the distinctive Achanarras lake horizon that contains a rich and diverse fish fauna. The Achanarras lake was wide and deep and would have been filled by rainfall from a monsoon system at an insolation maximum. Faunal elements within the lake are in common with the Kernavė Member in Estonia and this level can be conodont dated as late Eifelian eiflius or ensensis Zone. Therefore the group of lacustrine flooding climatic events that occur at and above the Achanarras level can be correlated with the marine Kačák Event ( sensu lato ) and both can be regarded as having a common climatic cause and driven by an insolation maximum. A reconstruction of the Orcadian Basin drainage system and a water balance model based on the calcium flux within the lake shows that a very significant volume of water would have been seasonally discharged to the Rheic Ocean and would have caused an additional environmental effect.