Coastal Features: The Great Unconformity and The Cretaceous Blanket
The Great Unconformity and The Cretaceous Blanket
The sediments which make up the Jurassic Coastline were deposited in the following order, Triassic, Jurassic and Cretaceous, with the oldest rock, the Triassic sitting at the at the bottom of the pile.
Part way through the Early Cretaceous Period the sea levels dropped and the layers of rock were tilted to the East by earth movements. Overtime the exposed rocks were eroded before sea levels rose again, depositing more Cretaceous sediments.
The combined tilting and erosion explains why the Jurassic Period is completely missing in East Devon and why areas of cliff all along the coastline are capped with Cretaceous rocks which are millions of years younger than the sediments laying directly beneath them.