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Jurassic Coast
Osmington Mills - Traces of life
Location: Osmington Mills
Rock Type: Limestone, mudstone and sandstone.
Age: Jurassic 155 million years old
Features of Note: Trace fossils
The geology in detail
The cliffs east from Osmington Mills are made of a rock sequence known as the Corallian. It is a very varied and complex sequence of limestones, mudstones and sandstones that all formed in quite shallow water. The Bencliff Grits and Osmington Oolite parts of the Corallian tend to contain very clear and abundant trace fossils. The Bencliff Grits form a well exposed section of sandstones and the Osmington Oolite appears beyond and up to the next headland, known as Bran Point. The Bencliff Grit is a soft sandstone that contains large ‘doggers' (hard rounded concretions). The Osmington Oolite is made up of thin layers of shelly limestones and clays and is capped by a thicker layer of white oolitic limestone. All these layers contain spectacular burrows formed by various types of animal including worms, gastropods, bivalves and crustaceans.
The ancient environment
The Corallian represents an ever changing environment that gave rise to the different layers of rock. The shelly limestones, sandstones and mudstones formed in generally shallow water areas like lagoons, tidal areas and slightly deeper offshore areas. The oolitic limestones show that sediment supply was occasionally cut off and oolitic shoals developed. These appear as a kind of sand made up of tiny balls of limestone. Modern day oolitic shoals are forming in the Bahamas, which gives us a good indication of what the ancient environment of the Osmington Oolite must have been like - shallow and warm. The creatures inhabiting the sea bed in this tropical paradise would have burrowed in the sediment either to make their homes or to find food. Their tracks and trails give us a clear picture of a well populated environment without having to find the actual remains of the creatures. They are particularly important to show that soft bodied animals like worms were also present. With no hard parts to fossilise, a burrow is normally all the evidence we have to show worms were living in an ancient environment.
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Orcombe Point - The beginning of the story
The western end of the World Heritage Site and the oldest rocks on the Jurassic Coast. Striking Red sandstones and mudstones can be seen in the cliff and the ‘geoneedle' on top of Orcombe point marks the start of the ‘walk through time'.
Budleigh Pebble Beds - Mountains and rivers
An incredible river deposit of pebbles from
across the channel and sandstones with ancient plant roots.
Ladram Bay - Sea stacks and the E.Devon AONB
Ladram Bay is a picturesque beach characterised by several
high sea stacks. It is one of the highlights of the East Devon Area of
Outstanding Natural Beauty (AONB)
Sidmouth - Desert dweller in the Otter Sandstone
Sidmouth is a traditional British seaside town bounded
within a wedge of red sandstone.
Beer - A story of stone Part 1
Beer is a picturesque fishing village and a source for
the famous Beer Stone.
Lyme Regis - World famous fossil site
Lyme Regis is famous worldwide for the abundant and
well preserved fossils that are found there eroded from the local cliffs.
Charmouth - World famous fossil site
Charmouth is famous worldwide for the abundant and
well preserved fossils that are found there eroded from the local cliffs.
Golden Cap - The highest view on the south coast
Golden Cap is the highest point on the south
coast and gives a fantastic viewpoint of this western part of the World
Heritage Site.
Chesil Beach - Finest barrier beach in Europe
Chesil Bank is one of the finest examples of a barrier
beach in Europe. Its formation is a direct
result of impact of the Ice ages on the geology and coastal processes of West Dorset.
Osmington Mills - Traces of life
Fantastic trace fossils can be seen on the beach at
Osmington Mills. Some of the best along the whole of the Jurassic Coast.
Durdle Door - The natural arch
Durdle Door, a huge natural rock arc, is an internationally
famous landmark and one of the most characteristic and spectacular features
along the Jurassic
Coast.
Lulworth Cove & Crumple - a geography pilgrimage
Lulworth Cove is a quintessential location for
the study of different rates of erosion in the formation of bays and headlands.
It is also a beautiful and popular tourist destination.
Old Harry Rocks - The end of the story
This is the eastern end of the Jurassic Coast
and where the youngest rocks on the world Heritage Site are exposed. Brilliant
white chalk has been eroded into steep cliffs and the famous collection of sea
stacks known as ‘Old Harry Rocks'.
Copyright 2011 Jurassic Coast
Copyright 2011 Jurassic Coast