The folded rocks are seen in exposed and submerged nearshore reefs, and cliffed headlands where upfolds bring the harder Black Rock Sandstone above sea level.
In south and east Dorset this resulted in the formation of two enormous structures, known as the Weymouth and Purbeck anticlines or upfolds.
The upfolds that occur become mountains (these upfolds are called anticlines) and the down folds are called synclines.
In the process, domes, cavities, faults and anticlines (upfolds of the earth with cores of salt) were created.
They may have a combination of upfolds and downfolds resulting in very complex structures.