Fossil collecting – Isle of Wight Geology and Palaeontology

A FOSSIL HUNTER’S PARADISE ISLAND

“No other area of comparable size in England has such a variety of formations in easily accessible exposures and containing such a diversity and abundance of fossils.”
(Alan Insole, Brian Daley & Andy Gale. 1998. The Isle of Wight. Geologists’ Association Guide No.60. London)

An almost complete succession representing deposits laid down from the Early Cretaceous to the late Paleogene, a time span of almost 100 million years commencing about 130 million years ago, is exposed on the Isle of Wight. Above this are important but less well known Quaternary deposits which, apart from yielding plant and animal fossils, also yield the tools of early Man. The Cretaceous – Paleogene succession is unrivalled anywhere in Europe and the variety of vertebrate fossils to be found, and in particular dinosaur and mammal fossils, make the Island a place of international importance to palaeontologists.

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Ancillus buccinoides
Middle Headon Beds, Colwell Bay
Height 33mm

ampullina100

Ampullina Grossa
Middle Headon Beds, Colwell Bay
Height 18mm

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Outline geological and location maps of the Isle of Wight

The Island’s beaches are the best places to collect fossils and as many of these are located in the Island’s Areas of Outstanding Natural Beauty, fossil collecting here is a special and enjoyable experience at any time of the year. What’s more, the cliffs are constantly subject to erosion by wind and waves so there is always something new to find. However, due account must be taken of the tides and weather to ensure that you are not cut off or swept out to sea and it is important that nothing is done which might damage the Island’s geological and palaeontological heritage. So, be safe, and follow the Geologists’ Association’s Geological Fieldwork Code.

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The Early Cretaceous Wessex Formation exposed in Brighstone Bay
with Upper Cretaceous chalk cliffs in the distance.

What’s to be found?

Dinosaurs are, of course, the Island’s most famous fossils with more than twenty species having been found so far and new discoveries coming to light all the time.

Recently, the most exciting discoveries have been the bones and teeth of large and previously unknown carnivorous dinosaurs. Neovenator described in scientific papers in 1996 and in 2001 and Eotyrannus, an early relative of Tyrannosaurus Rex described in 2001, are represented by partial skeletons.

Another exciting discovery was made in 2003. Teeth belonging to a very large and extremely fearsome relative of the already scary Velociraptor, made famous in the kitchen scene from the film “Jurassic Park”, were found and identified by the author who apart from being an Isle of Wight Farm and Country Holiday Group member is also a University of Portsmouth research palaeontologist Dr Steven Sweetman. Most recent of all (2011) has been the discovery of a partial skeleton of a long-necked sauropod dinosaur. The best of what has been found, including the new teeth, is on display at Dinosaur Isle at Sandown, where visitors can also see museum staff cleaning and preparing bones of the new skeleton. Island Gems and the Isle of Wight Dinosaur Expeditions Cooperative operate group tours to the easily accessible dinosaur localities.

Steve Sweetman provides a more comprehensive service for individuals and small family groups. This covers all the dinosaur sites, including the remote ones, localities yielding Cretaceous marine fossils and localities yielding Paleogene and Quaternary fossils. Steven’s primary research interest concerns the small animals that lived in the shadow of the dinosaurs, the tiny bones and teeth of one of which are shown here.

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Neoventor takes on Polacanthus
From Dinosaurs of the Isle of Wight Palaeontological Association Field Guide to Fossils: 10. Eds D M Martill and D Naish
With kind permission of the Assocation
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Iguanodon foot cast on the beach at Compton Bay. 50p coin for scale.

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Bones of an extinct, salamander-like, albanerpetontid amphibian.

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Reconstruction of an albanerpetontid
Dinosaurs, exciting as they are, make up but a tiny proportion of the Island’s fossil record. From the same rocks which yield teeth and bones of dinosaurs, remains of crocodiles and fish are common although these are usually represented by isolated teeth, bones, scutes and scales. In strata overlying those from which most of the dinosaurs remains have been recovered the remains of pterosaurs occasionally come to light. Above these the sea flooded the land and fossils of sea creatures are common including ammonites, ‘lobsters’, bivalves, brachaeopods, sea-snails, sea urchins and the teeth of sharks.

These strata, which were laid down in the middle and Late Cretaceous, comprise muds and sands, and the Chalk which now forms the spine of the Island culminating in the impressive white cliffs below Culver Down in the east and in the famous Needles rocks in the west. Each rock type represents a different environment and each environment favoured a different community of animals and plants and it is this which accounts for the great diversity of fossils to be found.

The ammonite Euhoplites from the Upper Cretaceous Galt Clay ammonite200

The diversity of rock types and the forces that have acted on them since they were laid down also account for the Island’s unique, varied and beautiful scenery, and for its abundant and diverse wildlife.

At the end of the Cretaceous, as everyone knows, the dinosaurs (but not birds which are now considered to be dinosaurs!) and many other animals became extinct. This time on the Isle of Wight was marked by a period when the Chalk was uplifted and eroded before sinking to or below sea level again and it is indeed fortunate for the fossil collector that this was so because the sequence of rocks which follow the Chalk are also an extremely rich source of fossils. At times the sea inundated the land and marine fossils can be found. At other times the rocks record periods of sedimentation in lagoons, fresh water lakes and terrestrial environments. Mammals had taken over from the dinosaurs as the dominant land animals and their bones and teeth can be found together with bones and other remains of the crocodiles, turtles, fish, snails, etc., with which they lived. In some places beautifully preserved leaves can also be found and in others even the delicate wings and bodies of insects are preserved.

Following the time when these fossils were first buried there is a long gap in the rock and fossil record during which time the Cretaceous and Palaeogene strata were folded by forces which further south produced the Alpine mountain range. Then came the Ice Age when sediments were again deposited burying the remains of plants and animals. Most of these including such things as hazel nuts and acorns are familiar today but some, such as bison and mammoths disappeared with the ice. It was only at this late stage in geological history (a mere 7000 years or so ago) that the sea finally breached the chalk cliffs connecting what are now the Needles on the Isle of Wight and Old Harry Rocks in Dorset, flooding Poole Bay and separating the Island as we now know it from mainland Britain.

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Striatolamia macrota
Bracklesham Beds
Height 55mm
Polymesoda convexa
Lower Hamstead Beds,
Bouldnor. Width 23 mm
Pusillina200 dissostoma200
Pusillina turbinata
Upper Hamstead Beds,
Bouldnor. Height 3mm
Dissostoma mumia
Bembridge Limestone
Height 20 mm

/islandinfo/images of Eocene and Oligocene fossils kindly supplied by Alan Morton: www.dmap.co.uk/fossils/

For more information about the Island’s geology, fossils and natural history, please feel free to contact Isle of Wight Farm and Country Holiday Group member Steven Sweetman
telephone on 01983 822691 or by email: s@mys.uk.com.
He would be delighted to answer your questions.