The geology of this LGAP region includes the Mesozoic and Cenozoic Eras of Earth history, a period spanning 250 million years.

This vast expanse of time saw many changes in depositional environment recorded in the rock succession.

In East Devon terrestrial red beds deposited in the hot desert climate of the Triassic are overlain unconformably by later marine sediments of the Cretaceous. During the late Triassic the sea transgressed across the low lying deserts creating a marine environment. Much of West Dorset is formed from Jurassic sediments that record changing marine conditions and contain an exceptional fossil record. Cretaceous Chalk and sands lie unconformably across the central swathe of Dorset covering much of the Jurassic outcrop. In the east more recent deposits of the Cenozoic, sands, gravels and clays overlie the Cretaceous rocks, These deposits give rise to important heathland habitats.

Along the south Dorset coast, Jurassic rocks of the Portlandian supply the world with building stone and the Purbeck beds record the transition into the Cretaceous revealing dinosaur footprints and a fossil forest.

In the north and west of Dorset the distinctive Inferior Oolite was widely quarried for local building stone.

This diverse geology gives rise to landforms which in turn provide us with a diverse geomorphology, range of soil types, natural landscape, biodiversity and wealth of nature. The importance of these features in Dorset is reflected in the designation of over half the county as Areas of Outstanding Natural Beauty (AONBs).

Chesil Beach, protecting the inland water known as The Fleet is one of the worlds finest barrier beaches and is of international importance for birds and wildlife. The structural ridges and up turned strata of the Isle of Purbeck and the Weymouth anticline lead to a dramatic landscape.

In East Devon and West Dorset, landslides provide an outdoor classroom for students but can also threaten coastal towns like Lyme Regis.

Dorset and east Devon's coastline has 66 Geological Conservation Review Sites all of national and international importance within Earth science. Many SSSI's in Dorset & East Devon are listed for geological interest.