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Fossil Hunting the Jurassic Rocks of Dorset's Jurassic Coast

Updated: Apr 21, 2022

Learn about how fossil hunting the Jurassic rocks of Dorset was the inspiration for Fossil Coast's own Lime Stone London Dry Gin and Kimmeridge Rum Spirit. Understand the origins of why the upper succession of Kimmeridge Clay transformed into a rich dark expression of rum spirit using blackcurrant, cider apple and cinnamon as botanical's along with sugar cane molasses.

The Jurassic Coast is 155km (95 miles) of coastline spanning from East Devon and Dorset and comprises a near-continuous sequence of Triassic, Jurassic and Cretaceous rock exposures, fossils and cliffs, beaches, lagoons, landslides, bays, stacks and raised beaches representing almost all the Mesozoic era 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 inscribed in 2001. World Heritage Sites are places of “outstanding universal value” and recognised as part of the heritage of all mankind. The Jurassic Coast or “Dorset and East Devon Coast” is one of 1,154 inscribed sites worldwide and now 32 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 Period

The Jurassic Period (201-145 million years ago) of "Age of the Dinosaurs" is named after the Jura Mountains on the border between France and Switzerland where rocks of this age were first studied. The Prussian scientist Alexander von Humboldt was studying a series of carbonate rock deposits in 1799 and named them the "Jura Kalkstein". Along the Jurassic Coast of Dorset the Jurassic rocks and fossils span from Lyme Regis to Swanage.

The Jurassic geological and fossil record of Dorset shows that the Earth's climate changed from hot and dry to humid and subtropical. It was a time when the giant landmass of Pangea began to break up and the underlying plate tectonics created Laurasia in the North and the continents of North America and Eurasia.

The Jurassic Period was very volcanic and he processes of continental rifting by the Earth 's tectonics opened up new oceanic domains. Parts of Britain including southern England saw a general expansion of tropical seas in which a sequences of clays, mudstones, limestones and sandstones were deposited. These geological changes had the dramatic impact of fuelling an abundance and diversity of life indexed by ammonites, belemnites and marine reptiles including dinosaurs.

During the Jurassic Period the dry deserts began to experience a dramatic ecological transformation through the presence of more rain. Deserts were changing from being inhospitable places to becoming green places irrigated by rivers and lakes creating new ecosystems and habitats for plants and herbivorous (plant eating) and carnivorous (meat eating) animals, dinosaurs and the earliest known birds to evolve.

During the Jurassic Period the food chain and chemistry of the oceans changed leading to the evolution of spectacular marine-based creatures to emerge and dominate. In these warm Jurassic Period seas, the emergence of photoautotrophs or single-celled organisms called phytoplankton captured carbon and calcium in huge quantities. These organism would become food a primary drivers of marine life evolution alongside the environmental variables during the Mesozoic.

The Lower Jurassic is linked with the vertebrates found in Lyme Regis between Pinhay Bay and Seatown - Be sure to visit both Lyme Regis Museum and Charmouths Heritage Coast Centre to see their exhibits. Within the Blue Lias rock of Lyme Regis fossilised reptiles, ichthyosaur's and the oldest known thyreophoran (armoured) dinosaur called the Scaelidosaurus harrisoni Owen was discovered. Lyme Regis is particularly famous not only for its reptile remains but also the towns long association with Jurassic Coast pioneering palaeontologist and fossil collector Mary Anning.

Mary Anning famously discovered with her brother Joseph the first ichthyosaurus (‘fish lizard’) specimen in 1812 aged only 12; the first complete long-necked marine reptile called a plesiosaurus in 1823; the first British example of a pterodactyl or flying reptile called a Dimorphodon in 1828 and in 1829 she excavated the skeleton of a Squaloraja, a fossil fish thought to be a member of a transition group between sharks and rays. Other Lower Jurassic localities for fossils hunting include the beaches below Golden Cap, Thorncombe Beacon and Stone Barrow.

The Middle Jurassic is exposed between Watton Cliff and Tidmoor Point and east of Weymouth below Ham Cliff. At Watton Cliff, microfossils such as brachiopods are found mostly in the grey Frome Clay with a more diverse range of fossils found in the rock formation called Forest Marble that includes crinoids, plant remains, fish, shark’s teeth, crocodiles, amphibians and reptiles. The Forest Marble is not a true marble but rather a limestone that has been hardened by heat. The Forest Marble Formation is marked at its base by the Boueti Bed deposited during the Bathonian Age, containing the brachiopod Goniorhynchia boueti.

Among the final rock succession of the Upper Jurassic is the Portland Limestone found on the coasts of the Isle of Portland and Purbeck, Portland Harbour and along the banks of the Fleet lagoon, Black Head and Bran Point near Osmington.

Historically these rocks have yielded bones of plesiosaurs and ichthyosaurs, Portlandian reptiles, Pavlovia (late Jurassic) ammonites. A unique feature of the upper Jurassic on Portland is the fossil forest.

Other interesting fossil hunting localities include Bowleaze Cove and Furzy Cliff (Lat/Long: 50.63539886,-2.42638208) near Weymouth known for its Oxford Clay and the Corallian Beds are where fossil finds have included the dinosaur Metriacanthosaurus parkeri and remains of ichthyosaur and plesiosaur. Finding marine reptile bones is now rare. Most fossils are now found on the foreshore and particularly after slippages from the cliff. Both the Gryphaea dilatata and Lopha gregarea oysters and Cardioceras ammonite can be found.

Redcliff Point (Lat/Long: 50.63309860,-2.40814493) is a location to east of Bowleaze Cove and Furzy Cliff. This is a location a rocky tidal locality and most fossils are now found on the foreshore and particularly after slippages from the cliff. Prior knowledge of tide times is essential. The Gryphaea dilatata oysters and trace fossils can be found of Thalassinoides, Diplocraterion and Rhizocorallium are present. Myophorella hudlestoni, Pleuromya and Quenstedtia bivalves are plentiful, and also ammonites such as Cardioceras. Corallian Group ribbed shells such as Myophorella clavellate can be found on the beach.

Smallmouth Sands (Lat/Long: 50.5924,-2.46573) is located on the marine derived claystone, "shale", siltstone, mudstone of the Kimmeridge Clays of the Jurassic Period. This location has yielded turtles and pterosaurs along with bivalves including Deltoideum (Deltoideum) delta; remains of reptiles including Geosaurus, Crocodylomorpha, Machimosaurus, Pelobatochelys blakii and saurischian, or "lizard-hipped" dinosaurs such as Duriatitan humerocristatus and Sauropoda.

Kimmeridge is by some way one of the most famous fossil locations along the Jurassic Coast. Kimmeridge Bay is made famous by the superb collection of The Etches Collection of crocodilians, pterosaurs, plesiosaurs, pliosaurs and ichthyosaurs found in this location.

The Kimmeridge Clay Formation is composed of fossil-rich mudstones and oil shales which originally accumulated as soft sediment at the bottom of the sea approximately 156-148 million years ago. This interval of 8 million years spans both the Kimmeridgian Stage and part of the subsequent Tithonian Stage of the Late Jurassic Epoch. Today much of the Kimmeridge Clay is elevated above sea level and outcrops locally in the cliff-face and on the foreshore between Brandy Bay in the west and Chapman's Pool towards the southeast.

NOTE: Kimmeridge Bay is owned by the Smedmore Estate and is also a Site of Special Scientific Interest. Fossils can be seen on the foreshore or within the cliff face. Collecting from the cliff face is dangerous and also forbidden, but most fossils can be collected (with permission) from the foreshore, especially in areas of shingle.

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