Triassic sandstones of the Northern Irish Sea have been correlated on wire-line logs with the succession at the outcrop in Cheshire (Colter & Barr 1975). Recent work on well sections confirms the lithological similarities of these units with the supposed onshore equivalents.

Porosity and permeability of the sandstones are related in the first place to original grain size, particularly argillaceous content. Superimposed on this primary variation are the effects of various diagenetic phenomena: (1) Tangential illite coatings; (2) Platy illite normal to grain surfaces; (3) Calcite cement; (4) Compaction and pressure solution; (5) Quartz overgrowths. Porosities and permeabilities measured in core plugs have been related to primary textures and to the occurrence of these diagenetic changes.

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