Palaeogeographic reconstructions for the northern margin of the southern North Sea Carboniferous Basin indicate generally east-west trending, facies belts in a generally aggradational, alluvial depositional setting. This east-west orientation suggests that the Westphalian coal measures and alluvial red-bed successions in the UK and Netherlands sectors should be treated together and studied from a common stratigraphical viewpoint. Despite this there have been widely differing approaches to, and interpretations of, the Upper Carboniferous stratigraphy on either side of the UK-Netherlands median line.

A study of fifty key well sections from the Cleaver Bank High and areas to the south and west, has provided a detailed, integrated miospore biostratigraphy and chemostratigraphy, which, along with e-log, sedimentological and mineralogical data is used to produce a unified lithostratigraphy applicable to both sectors. This is based upon a synthetic, composite, holostratigraphic reference section representing an idealised and complete sequence of the Upper Carboniferous strata preserved in the area. Key to understanding the stratigraphy of the laterally variable alluvial succession is the biostratigraphical and geochemical recognition of isochronous stratal surfaces (principally marine flooding horizons) which allow the subdivision of the sections into temporally and genetically related units.

The recognition of a significant and widespread, intra-Carboniferous unconformity, which in places removed several hundreds of meters of Duckmantian and Bolsovian strata, is of prime importance in understanding and correlating the geology of the area. In places the unconformity erodes down to strata of the earliest Duckmantian and is everywhere overlain by mid Bolsovian strata. Conformable or near-conformable section correlative to the unconformity is preserved in the south-eastern part of the study area. The areal development of the unconformity has significance for our ability to provide accurate original isopachs for the truncated sequences. The presence of the unconformity has significant implications for the tectonic development of the Upper Carboniferous of the area which has generally been considered as developing in a tectonically quiescent, thermal-sag basin. The newly established detailed stratigraphy allows mapping of the subcrop of this intra-Carboniferous unconformity which indicates significant uplift of the northern basin margin during the early Bolsovian with recycling of significant volumes of sediment into the basin centre. The mid Bolsovian timing of this tectonic movement is consistent with a major phase of nappe loading on the Variscan Front, and contemporary erosive unconformities elsewhere along the Variscan foreland.

Further, there is compelling evidence based upon differential subsidence patterns to indicate continuous tectonic influence upon sedimentation from as early as the late Langsettian. There appears to be strong syn-depositional structural compartmentalisation of the area with the major NW-SE trending structure of the Murdoch Ridge cut and offset by orthogonal NE-SW trending normal growth faults. Mapping of sandstone thicknesses, net-to-gross ratios and phytogeographic variations, help constrain the areal distribution of major braidplain facies belts and suggest that many of the major sandstone reservoir units are arrayed along the footwalls of syn-depositional half-graben.

The study demonstrates the similarity of Upper Carboniferous sequences preserved in the UK and Netherlands sectors of the North Sea. The consistent correlation of a series of formations allows inferences to be drawn regarding to the evolution of the northern margin of the southern North Sea Carboniferous basin. Most importantly, a significant tectonic influence on sedimentation is apparent.