Over about 100 million years during the Palaeozoic, the assembly of Pangea resembled a slow motion
motorway pile-up. In southern high latitudes a previous huge continent, called Gondwana, was rifting off small slices and lumps of crust from its northern edge. Several of these pieces were being moved northwards on tectonic plates to collide with a quite large continent called Laurentia (Canada, America and Greenland) positioned across the equator.
In the Devonian period, Baltica collided from the east, forming a larger continent, called Laurussia, followed by a small slice, called Avalonia, colliding from the south (Fig.1.) These collisions resulted in the Caledonian fold mountain range being formed across eastern America, Scotland and Norway and the geological unification of the British Isles area by plate collision. Scotland and Northern Ireland were part of Laurentia, whilst north-west Europe, England, Wales, Southern Ireland, plus a slice of Newfoundland and Nova Scotia were part of Avalonia, itself a rifted piece of Gondwana. It was on the southern edge of Laurussia that the Carboniferous coal swamps formed next to the ocean to the south.
Towards the end of the Carboniferous another slice of Gondwana, called Armorica (mainly NW France and Germany) collided from the south, to be followed by other bits and pieces and then the main mass of Gondwana, raising the Variscides mountains. The only traces of the ocean floor that were once between these pieces are now in the rocks along the joins between them.
Prior to the final impact the crustal area now the British Isles was aligned nearly NW to SE, but, in addition to a northwards drift, the impact also began a clockwise rotation that moved it into its present, more North to South alignment. Our area had become part of a rock desert, with an upland area almost where the Pennines are now. To the east was a rock slope, with ridges, running down to a desert basin, which had breccias forming along the edges, dunes further into the basin and red muds in the centre, where any stream flow formed temporary salina lakes with red muds and salts (Fig 3.) Flash floods flowing into desert basins are known today and in other parts of England, rare plant fragments, plus amphibian and reptile bones and footprints are evidence that conditions were not completely dry.