By the early Permian Period, earth movements had drastically altered the geography of the area that was eventually to become Yorkshire.

The driving forces of plate tectonics had carried the region north of the equator and lifted it above sea-level. The rocks formed in the great Upper Carboniferous delta had been forced up to form low hills which were now being eroded in the hot, dry climate of a continental interior. The area was part of a vast desert, with low mountains to the north and west.

Winds, blowing from the north-east, built up great sand dunes that slowly spread across the eroded Carboniferous rocks filling in hollows in the landscape with layers of yellow sand.

One of the few places where these sands can be seen today is in an abandoned quarry at Thorner.

Dune-bedded sands at Thorner