COLLECTIONS & RESEARCH

Fossils As You See Them on the Beach

People are so used to seeing spectacular fossils in museums and on television that they often forget how very different they look when they are discovered. Many fossils are incomplete or distorted when they are found. An animal’s carcass on the sea floor would be eaten by scavengers, rot and finally be crushed by the weight of sediment deposited on it. Millions of years later modern landslips and wave action disturb the remains still further before they are exposed on the beach. Often you only see a fragment of the surface of the fossil showing, perhaps the side of an ichthyosaur vertebra (section of backbone) or a patch of shiny fish scales in the edge of a piece of shale or limestone. Broken and eroded rocks may show a section through part of the fossil. Click here for information on our Fossil Walks.

Ammonite ledge Monmouth Beach

Often fossils can be eroded at strange angles.

These images show what you may see on the beach and will help you to recognise fossils.  Spotting fossils is a skill and you will improve with practice and knowledge.  When you see fossils in museums or shops look at the colour and texture of the rock and see if you can work out what the person who first found the fossil spotted.  Talking to more experienced collectors can also be extremely helpful.

On Monmouth beach to the west of the cobb visitors can see a layer of limestone called the ammonite graveyard or the ammonite pavement.  This layer of rock is famous for the large ammonites it contains.  The picture on the right shows a typical view of part of the pavement.  Most of the ammonites have a well-preserved outer coil and a crushed middle.  While admiring the ammonites remember to look for other fossils.  The fossils below can also all been seen in the limestone pavements on either side of Lyme Regis, but especially to the West of the town on Monmouth beach.

Trace fossils Brachiopod shell fossils

Devil's toe-nail fossil Snail shell fossil

Sometimes you can find something more unusual such as the bones of marine reptiles. During the summer of 2006 the scattered remains of a small ichthyosaur gradually eroded out of the ammonite pavement.  Sadly the bones have now eroded away completely but the photograph (below left) shows what they looked like.  The discs that make up the backbone are called vertebrae.  Ichthyosaur vertebrae are not very thick compared to their diameter.  Their other characteristic is a deep depression in both sides.  This means when they are eroded halfway through the cross-section looks like a bow tie.  You can see a row of vertebrae like this at the left hand side of the photograph.

Ichthyosaur eroding out of the ammonite ledge Eroded fossil lobster

In the paler coloured Cretaceous rocks you can find bivalve shells, sea urchins, ammonites and if you are lucky fossil lobsters.  These normally appear on the edge of large boulders as black lines and circles.  These lines are where the lobsters black carapace has been worn through by the tide. The picture above right shows a lobster eroded in this way.  The oval shapes at the bottom of the picture are sections of the animal’s claws.  You can probably see why so many people fail to recognise fossil lobsters!

On the beach to the East of Lyme Regis there are also fossils to be found.  At this side of Lyme it is easy to be cut off by the tide so make sure you check the tide times before you go out.  You normally want to be going out about 2 hours before low tide and you will have until about the same amount after low tide.  The area to watch is the bend in the concrete sea wall.  The tide reaches the sea wall before it covers the beach.  If there is a strong wind from the sea or a very high tide you might have even less time.  You also need to watch the cliffs and avoid going too near.  Falls of rock are most common in Winter, especially after heavy rain, but can occur at any time of year.

When you do get out onto the beach at the foot of Church Cliff in between Lyme and Charmouth you can find a variety of fossils.  Finding them however, has been made harder by the rubbish which has come onto the beach from the May 2008 rockfall.  This fall brought down hundreds of thousands of tons of limestone and shale containing fossils, but also part of the old town rubbish dump which was on top of the cliff.  Some pieces of discarded rubbish look a lot like fossils.  Here are some of the things which are often mistaken for fossils;

Carbon rod: not a fossil! Melted glass: not a fossil!

Among all this rubbish you can come across some genuine finds.  These include the bones of Ichthyosaurs and occasionally bones from Plesiosaurs.  These two types of marine reptile were both first discovered by Mary Anning at Lyme Regis.  It is rare to find complete skeletons; mostly you find loose bones in the shingle on the beach.  The most commonly found part of the animals skeleton are sections of the backbone, these are called vertebra.  Another frequent find (if you know what to look for!) are coprolites.  These are the fossilised poo of marine reptiles, sharks and fish.

Jurassic coprolite: fossil droppings Ichthyosaur vertebrae

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