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Fossil Hunting the Jurassic Coast's Triassic Rocks

Updated: Apr 21, 2022

Learn about the Jurassic Coast's Triassic's rocks and fossils whose familiar red sandstone is the inspiration for Fossil Coasts Drinks Red Bed Berry Gin Liqueur.

The Jurassic Coast is 155km (95 miles) of coastline spanning from East Devon to Dorset and comprises of a near-continuous sequence of Triassic, Jurassic and Cretaceous rock exposures, fossils and cliffs, beaches, lagoons, landslides, bays, stacks and raised beaches. The Jurassic Coast represents almost all of the Mesozoic era dated between 65 - 200 million years ago. The Mesozoic era became best known as the age of giant reptiles and dinosaurs.

The Jurassic Coast starts in the West at Orcombe Rocks near Exmouth (50º 36’ 23ºN, 3º 23’ 03ºW) and continues through to Studland Bay in Dorset (50º 38’ 24ºN, 1º 56’ 21ºW). The seaward boundary of the Jurassic Coast stretches to the mean low water mark. The Jurassic Coast includes eight stretches of coast line and a number of “gateway towns” including Budleigh Salterton, Sidmouth, Seaton, Lyme Regis, West Bay, Weymouth and Swanage.

The Jurassic Coast was England’s first UNESCO (United Nations Educational, Scientific and Cultural Organisation) World Heritage Site to be inscribed in 2001.

World Heritage Sites are designated as places of having “outstanding universal value” and recognised as part of the heritage of all mankind.

The Jurassic Coast or “Dorset and East Devon Coast” is now one of 1,154 inscribed sites worldwide and among 32 inscribed in the United Kingdom. The guardians of the Jurassic Coast are the Jurassic Coast Trust who in 2022 celebrate 20 years.

The Jurassic Coast is among other natural World Heritage Sites including the Giant's Causeway and Causeway Coast, The English Lake District, Cornwall and West Devon Mining Landscape and The Slate Landscape of Northwest Wales. In 2021, the Royal Geographical Society (with IBG) in partnership with outdoor brand Merrell listed the Jurassic Coast as one of the UK’s "Seven Natural Wonders" chosen for their shared beauty, uniqueness, and geological significance Pistyll Rhaeadr, Loch Coruisk and the Cuillins, Wastwater, Dovedale, the Needles on the Isle of Wight (image by Amir Azimi on Unsplash), and the Giant's Causeway.

The Jurassic Coast represents almost the entire Mesozoic Era dated between 252 million - 66 million years ago all in one coastline. The Mesozoic Era or “middle life” is the second of three major geological era's sandwiched between the Palaeozoic (541 million - 252 million years) and Cenozoic (66 million years ago to the present day). In combination all three eras form the Phanerozoic when physical life first emerged and the ancestors of major plant and animal groups that exist today first appeared. The Mesozoic era is best known as the time of the emergence and extinction of dinosaurs.

The rocks of the Jurassic Coast show the major changes in the pattern of life during the Mesozoic period through its fossil record of vertebrates, invertebrates and plants. There is a richly diverse range of plants, insects, marine invertebrates, fish, marine and terrestrial reptiles and mammals found across the Jurassic Coast.

Many fossil exhibits can be seen at many of the museums and visitor centre's of Devon and Dorset. If you however decide to adventure out and discover your own fossils along the beaches it is advisable to follow the fossil collecting code of conduct. This code of conduct is in place so you don't have to take any risks, ensures you are aware of local conditions to remain safe and fossil hunt sustainably and enjoyably among the Triassic, Jurassic and Cretaceous rock.

The Triassic Period (252 - 201 million years ago) of the Jurassic Coast is characterised by red sandstone rocks exposed in the cliffs of East Devon seen from the gateway town of Exmouth. East Devon along with the Midlands and South Wales are the main areas of Triassic rock exposures in the United Kingdom.

The Triassic Period separates the Palaeozoic the earliest of three geologic eras from the Mesozoic Eras. The Triassic lasted approximately 50.6 million years and has three epochs called the Early Triassic, the Middle Triassic and the Late Triassic.

The red Triassic sandstone seen in East Devon was formed in a sandy desert environment and is made up of quartz crystals held together in an iron oxide rich cement that gives the rock its characteristic red colour (image below by Red Zeppelin on Unsplash). The red sandstone is also the inspiration to Fossil Cast Drinks Red Bed Berry Gin Liqueur whose red colour is achieved through the use of red currant, strawberry and raspberry botanicals.

The Triassic began after Earth's worst-ever extinction event that devastated life and is the reason why the fossil record of the Early Triassic is seriously impoverished. The Permian-Triassic extinction event, also known as the "Great Dying" was responsible for the extinction of up to 90% of all species 252 million years ago and it was not until the Middle Triassic that there was recovery of organisms and better environmental conditions.

During the Triassic Period, the environment was hot, dry and the landscape was covered by deserts. The environment led to the deposition of sandstones, salts and mudstones in deserts, rivers and shallow lakes.

Reptiles were common and the first dinosaurs evolved. The Triassic is largely defined by its extinctions and the time of the Earth's one giant landmass called Pangea.

In the main the Triassic rocks of East Devon have a rarity of fossils. In Budleigh Salterton the Triassic rock sits on the much older Budleigh Salterton Pebble Beds that date back to the Ordovician Period (488.3 - 443.7 million years ago).

During the Ordovician Period the northern hemisphere was almost entirely ocean and the southern hemisphere was mainly an ancient supercontinent called Gondwana consisting of the modern day continents of Antarctica, India, Australia, South America and Africa.

Within these Budleigh Salterton quartzite pebbles can be found Orthis budleighensis a very small brachiopod. Brachiopod are marine shell animals with two hard outer valves that are composed of calcite or chitinophosphate (calcium phosphate plus organic matter) hinged at the rear end, while the front can be opened for feeding or closed for protection. NOTE: There is a bylaw restricting the removal of pebbles from Budleigh beach and is enforceable with a fine.

The Middle Triassic (246 - 229 million years ago) is characterised by the Otter Sandstone Formation of the south coast of Devon. These rocks have been a source of reptile fossils since the nineteenth century particularly between Ladram Bay and Sidmouth.

Within the Otter Sandstone there is a layer fluvial conglomerates associated with braided rivers and streams over laid by siltstones and mudstones of the Sidmouth Mudstone Formation, part of the widespread Mercia Mudstone Group. Fossils are found in this area as it once was a wet sedimentary basin indicated by desert minerals like gypsum and those damper conditions allowed new habitats to develop and animals to colonise the river systems.

The most common of the Middle Triassic fossils are tetrapod's that means "four legs" in Greek. The principle tetrapod fossil localities include the prominent coastal landform of Otterton Ledge (East of Budleigh Salterton - Lat/Long: 50.62910080,-3.30525061 - see image right), Between Ladram Bay and High Peak; and from Chit Rocks looking east from Sidmouth towards the exposed rocks of Chapmans Rocks of Salcombe Hill Cliff and the distant Higher Dunscombe Cliff.

Among the most common fossils is the rhynchosaur Fodonyx spenceri believed to be medium-sized herbivore and the rarer fragments of an Archosaur (“ruling reptiles”) who are members of a subclass that also includes the dinosaurs, the pterosaurs ("flying reptiles"). Other reptile remains include evidence of the sail-backed predatory reptile Ctenosauriscus; the 6 meter long anystropheus‭ (‬Long strap‭) a shoreline predator; the procolophonid Kapes bentoni a small, superficially lizard-like parareptile also found in Russia and the much rarer fragments of the smaller diapsid Coartaredens isaaci. Amphibian bones such as the Temnospondyli are present. The fish Dipteronotus cyphus have also been reported, along with insects, conchostracans (clam-shrimp), and plants including conifer trees.

In the lower sections of the Otter Sandstone Formation are many vertical and irregular calcareous structures known as rhizoliths or rhyzocretions representing the mineralised moulds and casts of ancient rooting systems that have died away and the presence of paleosols or an ancient soils now incorporated into the Triassic geological record for South Devon.


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