Biostratigraphically well-calibrated exposures of Lower Jurassic rocks in the Wessex, Bristol Channel, Cleveland and Hebrides basins have been remeasured and interpreted in the context of sequence stratigraphy. The aim has been to see whether the stratigraphy and facies are compatible with the hypothesis that relative sea-level changes were synchronous across all these basins. The Lower Jurassic Series can be subdivided into four large-scale (so-called 2nd-order) lithologic cycles, with durations of approximately 3–10 my, that appear to be synchronously developed in all onshore British basins; the cyclic changes in facies become more extreme as the cycles young. Candidate maximum flooding...