The Spittles lies just to the west of one of the best fossiling places along the Jurassic Coastline at Black Venn. You can walk here from Lyme Regis, but care must be taken as you can get cut off by the tide. The area is also prone to rock falls and mudslides, particularly during winter storms.
Hotspots: The Jurassic Sea and Fossils, Charmouth Dinosaur, Sea Washed Fossils
The Charmouth Dinosaur
The cliffs around Charmouth hold a mystery. A local fossil collector, David Sole, has found the remains of a dinosaur, Scelidosaurus, but just how did a land dwelling reptile end up at the bottom of this deep Jurassic sea?
The Jurassic Sea and Fossils
The Jurassic clays around this area formed in a deep tropical sea, the soft muddy bottom of which was often stagnant, creating a sulphurous and anoxic environment, the best conditions for preserving the shells, bones and even soft tissue of dead prehistoric creatures.
Sea Washed Fossils
The base of the Black Venn mudslide is one of the best places to find fossils along the Jurassic Coastline. The sea washes the fossils out of the mud and leaves them to be found amongst the shingle between the boulders.
Coastal Features: The Great Unconformity and The Cretaceous Blanket, The Black Venn Mudslide, The Cretaceous Blanket and Cliff Erosion
The Cretaceous Blanket and Cliff Erosion
From the air, the instability of the cliffs along this stretch of the Jurassic Coastline is clearly visibly and they are eroded in several different ways.
From above, and where the cliff is capped by Upper Greensand, rainwater seeps through to the underlying impermeable clays. As the water builds up during prolonged periods of rainfall the cliffs below fail to support the extra weight and pressure from above, creating a landslide.
From below, the sea erodes away the cliff base. As more and more sediment is removed, the deposits of clay and shale above become less stable, resulting in cliff falls onto the beach, where the process then starts all over again.
This is why the cliffs here are so unstable and why it is a good idea to keep away. Mary Anning’s faithful dog was killed when a section of cliff fell on him.
The Black Venn Mudslide
One of the best fossil hunting locations lies between Lyme Regis and Charmouth at Black Venn.
The build up of rain water in the Upper Cretaceous Greensands resulted in Europe’s largest recorded mudslide during the winter of 1958, depositing a huge amount of material onto the beach.
A 2 acre boulder field at its foot is all that remains, but the cliff is still on the move, with regular, smaller slides bringing fresh fossil deposits down onto the beach below.
The best time to go fossil hunting around Charmouth is after a winter storm, when waves crashing up against the fresh mudslides and cliff falls wash the loose sediments away, leaving the cleaned fossils behind to be found in patches of sand between the boulders.
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.