Abstract

The assumption of a deltaic style of sedimentation for the bulk of the Lower Carboniferous beds of Scotland is validated by comparative studies in which it is possible to detect ancient equivalents of modern om-delta (deltaic plain), delta-front, interdistributary bay, lagoonal, prodeltaic, and associated open shelf environments. The various facies are interbedded in a manner indicating periodic marine or quasi-marine inundations of deltaic plain areas, and it is possible that man) of these inundations reflect diversion of sub deltaic outlets on constantly, but irregularly, subsiding foundations rather than cyclical changes in the provenance or eustatic changes in sea level.

The progressive southward and southwest-ward migration of the deltaic complex into shallow marine waters is indicated by major deltaic lobes emerging from a North Sea Basin complex and extending into the Midland Valley.

The Carboniferous deltas were very sandy, and there is a greater similarity with deposition in the modern Rhone Delta than with the Mississippi, Orinoco, or Niger Delta sedimentation. Rapid flow and high discharge rates probably accounted for the widespread formation of sand channel and point bars in the deltaic plain areas and the deposition of sand and coarse silt on the prodeltaic shelf.