Changing Channel Morphology and Magnitude in the Scalby Formation (M. Jurassic) of Yorkshire, England

Abstract An upward change in palaeochannel morphology from low sinuosity, possibly braided, to high sinuosity channels set in a matrix of overbank fines is deduced for the Scalby Formation. The resulting sandbodies are of sheet and ribbon morphologies, respectively. The early low sinuosity channels are thought to have carried much higher discharges than the later high sinuosity channels. The deduced upward changes in channel morphology and magnitude are thought to be due to initial hinterland upwarp causing high valley gradients and initial fluvial advance into the marine Yorkshire basin followed by rising sea level causing extensive alluviation, lowered gradients and final marine transgression of the Cornbrash sea over the defunct alluvial plains.