The Upper Carboniferous Deltas and Coal Swamps

Abstract

In southern Scotland and in England as far south as north Yorkshire the formation of deltaic deposits with coal seams and occasional marine limestones, and with lavas, described above, continued uninterruptedly into the Upper Carboniferous. Further south, as now seen in the southern Pennines, North and South Wales, conditions changed at this time and another series of great deltas began to be built outwards from the neighbouring land areas. These deltaic deposits form the Millstone Grit, the most characteristic rock-type of which is thick coarse sandstone, or ‘grit’, representing deltaic sandbanks. These grits are best seen on the south Pennine moors, especially in the Peak District. The change in lithology must reflect uplift of the land areas and increased transport of eroded, land-derived detritus into the sea.