Rhythmic Deposition in the Carboniferous Oil-Shale Group of Scotland

The Scottish Lower Carboniferous Oil-Shale Group consists predominantly of shallow water non-marine sediments (limestones, sandstones, and shales mainly) laid down rhythmically in intradistributary lagoonal tracts and channels at the western margin of a major delta system. A revised rhythmic unit incorporating limestone and commencing with sandstone at the base is proposed and described. There are three common partial units. The pattern of sedimentation is related to the activity of the distributaries and the physical state of the lagoonal waters. The comparative rarity of oil shales is probably due to the generally agitated nature of those waters.