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On this page:

What are fossils?

How are fossils preserved?

How are fossils dated?

Continents on the move

The major fossil groups

The art of fossil preparation

Looking after a fossil collection

Recommended books and online resources

Recommended museums

Jurassic ammonite from Charmouth, Dorset - a beautiful object and 190 million years old

Click here to view fossils for sale

What are fossils?

Fossils are the only direct evidence we have of life on Earth before humans. They can tell us about how animals evolved, how continents have shifted and how climates have changed throughout geological time.  Often beautiful, always mysterious, they are the remains of creatures that have been preserved in sediment that has now hardened into rock.  Most are at least 100 million years old, a period of time almost impossible to comprehend. 
Almost everyone has picked up a fossil at some time in their lives, be it a curious pattern in a pebble, or perhaps one of the famous ammonites from the Dorset coast. Good quality fossils are rarer, and usually require skill to extract them from the rock in which they are found. The soft tissue has usually decayed after death leaving only the hard parts – shells, teeth and bones – to be found as fossils.  A fossil may be the remains of the organism itself or a cast or impression of it in the rock.  Sometimes even footprints or burrows may be preserved. 
Minute details can often be preserved by the process of fossilisation. The structure of bones and shells can be completely replaced by minerals.  The creature has literally been 'turned to stone'.  Yet this process has produced a new and permanent beauty - a lasting record of prehistoric life on Earth.
There is no fixed rule as to how old, for example, a bone or shell has to be before it is regarded as a fossil but the word fossil is generally used to describe any animal or plant remains older than about 10,000 years, in other words before the end of the most recent glaciation which marked the end of the Pleistocene period (see geological timescale). 


Beautifully preserved Jurassic ammonites from the Kimmeridge Clay of Wiltshire. The iridescence of their original shells has been preserved after 160 million years of burial beneath the Wiltshire landscape.  


How are fossils preserved?
The vast majority of animals that have ever lived have disappeared without leaving a trace of their existence and only a tiny proportion have made it into the fossil record. For a living thing to be preserved as a fossil usually requires rapid burial so that the normal processes of decay will cease and scavengers prevented from destroying the carcass.  This explains why the vast majority of fossils are of creatures that lived in the sea or lakes where a carcass can be buried by sand, mud or other sediment.  Also the animal's remains must not be disturbed by creatures that live in the sea floor sediment or dissolved by water passing through it.  For it to be well preserved as a fossil it must also not be crushed by the weight of the overlying sediment. 
There are many ways in which a fossil can be formed. Bacteria will usually break down the soft tissue leaving the hard parts such as bone or shell (soft parts, such as skin and internal organs are only preserved under exceptional conditions).  Over a very long period of time the sediment will be impregnated with minerals and will harden into rock.  The hard parts of the animal will then slowly be replaced by minerals, which can preserve every tiny detail.  Alternatively, if an animal such as a sea shell is completely dissolved and the cavity infilled by minerals the fossil will be preserved only as a cast.  Fossils may also be preserved by encapsulation in tree resin, embalming in tar sand or deep frozen in permafrost.  Fossil leaves can be preserved in exquisite detail as thin films of carbon.  Colours may also be preserved, such as the iridescent layer on shells called mother of pearl, or new and beautiful colours may be created by dissolved minerals. 
Fossils less than a few tens of millions of years old may not be ‘fossilised’ at all and retain their original bone or shell material, but are still regarded as true fossils due to their age. 

These three million year old fossil gastropod molluscs (whelks) from the Red Crag at Walton-on-the-Naze in Essex are very young in geological terms.  They are true fossils although they resemble modern shells.  

How are fossils dated?
Britain has a remarkable variety of rock types, each formed in a different way at a
different time in the Earth's history.
Rocks which contain fossils were usually formed as a sediment deposited on the bed of
a sea or lake (known as sedimentary rocks) and these fossils are the remains of animals and
plants that lived at the time.  Some rocks obviously do not contain fossils, for example those formed as products of volcanoes.
Sedimentary rocks are found throughout Britain, evidence that great seas or lakes covered
all parts of the country at one time or other in the distant past. These rocks can be vast thicknesses, the Chalk, for example, is over 500 metres (1,500 feet) thick, deposited at a
time when almost the whole of Britain was under the sea.  We can understand how such a thickness can be deposited when we realise that this sea existed for nearly 30 million years!
All sedimentary rocks have been dated either by sophisticated laboratory techniques
or by correlating rocks in different areas to produce a continuous sequence. It is therefore very straightforward to date a fossil provided you know the rock in which it was found. 
This is done with the aid of a geological map or guide of the area which lists the local
rocks together with the geological period to which they belong.
The collector might not be able to easily identify all the fossils that he or she finds, but
there is normally no doubt about their age.

Polished slab of limestone from Cumbria showing a colony of coral.  The limestone is known as Carboniferous Limestone and has been dated to 330 million years (early Carboniferous period) when much of Britain was covered by a tropical sea.  All the fossils within this limestone will therefore be of creatures living in the sea at that time.


Continents on the Move

It is now well known that the continents are not fixed in position but slowly travel across the globe on rigid ‘plates’ which fit together rather like a jigsaw and thought to move because of large-scale thermal convection currents in the Earth’s mantle. The concept that accounts for plate motion is called plate tectonics. Britain, together with the rest of Europe, has travelled north (at one or two centimetres a year) for hundreds of millions of years and was, at one time, well south of the equator. This helps to explain the presence in Britain of fossils of animals and plants whose descendants now live in tropical climates. Plates are slowly created by volcanic activity and destroyed by submersion into the mantle.  This process continues today. 


When the theory of continental drift was put forward by Alfred Wegener in 1912 it was widely ridiculed.  One of Wegener’s main pieces of evidence in support of the theory was the fact that fossil leaves of the extinct tree Glossopteris (above) from the Permian period are found in South America, Africa, Australia and India but seeds of this tree could not have travelled over large expanses of water.  He therefore concluded that these continents must have been joined together in a ‘supercontinent’ known as Gondwanaland. Wegener’s ideas were not finally accepted until the discovery of plate tectonics in the 1960s.

 The major fossil groups

Below are the major fossil groups.  Fossils from most of these groups can be commonly found.  A notable exception is insects, which are very rarely preserved as fossils but are familiar to us because of their unique preservation in amber.

The general name for a fossil often includes the geological period to which it belongs, for example 'Carboniferous coral' or 'Jurassic ammonite'.  For information about the geological time periods referred to see the 'Timescale' tab above or click here for a geological timescale.

The art of fossil preparation

Although fossils can be found in most parts of Britain, some sites are more prolific than others, with some localities, such as the Dorset coast, yielding vast numbers from the cliffs, only to be broken up by the waves if not collected.*   Some fossils are found as loose specimens and only a wash is required.  Others will be found still embedded in the rock and some work will be needed to reveal them.  Extracting fossils from the rock in which they are enclosed (the matrix) is known as fossil preparation or ‘prepping’.  Many of the fossils for sale on this website have been prepared by professional fossil collectors who are highly skilled in their craft.

Fossil preparation is often a difficult and laborious business, especially in hard rocks such as limestone, and skill is required to ensure that the fossil is not damaged in the process, but if done well the results can be stunning.  Click on the image title opposite to find out how this is achieved.


*Advice on how to safely and effectively collect fossils yourself can be found in several of the books listed below, notably ‘British Fossils’ by Peter Doyle which is highly recommended.

Looking after (and enjoying)

a fossil collection

People purchase minerals or fossils for different reasons.  Some may simply want a unique decorative ornament for the home, others may be adding to an existing collection. Whatever the reason for acquiring a geological specimen it is useful to remember that we are only temporary custodians of them and that we will eventually hand them on to others - perhaps the next generation. It is important therefore to look after them and to retain the information that came with them. 

Click on the image title opposite for advice on on taking care of, or curating, a geological collection, whether it is of rocks, minerals or fossils. 

Recommended online resources


by Peter Sheldon and Andrew Tindle (2013

An expertly written interactive book on fossils found in Britain and other parts of the world. Profusely illustrated with detailed photographs and drawings, it is a useful guide to identify and enjoy the many and varied fossils commonly found.  Produced by the Open University in collaboration with the Sedgwick Museum of Earth Sciences, Cambridge. Designed for use with iPad.

Recommended books on fossils


The following books are recommended.  The excellent book 'Fossil Detectves: Field Guide' is available for purchase on this website.  Click here for details.  
Other titles may be available as second hand copies. 
Please click here for details of all geology and fossil books for sale.


By Andrew Ross. (2010). Published by the Natural History Museum, London.

By Neale Monks & Philip Palmer. (2002). Published by the Natural History Museum, London.

By Peter Doyle. (2008). Shire Publications.

By Paul Selden and John Nudds. (Second edition 2012). Published by Manson Publishing

By Paul Kenrick & Paul Davis. (2004). 
Published by the Natural History Museum, London.

By R. Croucher & A.R. Woolley. (1982).  Published by the British Museum (Natural History)/Cambridge University Press.

By Peter Sheldon. (2008). Published by the Open University.

By Richard Fortey. (Fourth edition 2009). Published by the Natural History Museum, London.

By Richard Fortey. (1997). Published by Harper Collins.

By Adrian Lister and Paul Bahn. (Revised edition 2007). Published by Frances Lincoln.

By Roger Osborne & Alistair Bowden. (2005). Published by the North York Moors National Park.

Edited by Denys Brunsden. (2003). Published by Coastal Publishing.

By Pete Lawrance and Sinclair Stammers. (2014). Published by Siri Scientific Press.



And finally, for the identification of the common fossils that can be found in Britain there are three books that are essential:

British Palaeozoic FossilsBritish Mesozoic Fossils and British Caenozoic Fossils have become classic works of reference for fossil collectors since they were first published in the 1960s.  They are published by the Natural History Museum and are reasonably inexpensive paperbacks. 



Recommended museums 

 Sedgwick Museum of Earth Sciences 
Downing Street, Cambridge CB2 3EQ. Telephone: 01223 333456

Situated in the centre of Cambridge, the Sedgwick Museum has a major collection of fossils with over a million specimens.  Fortunately, the public galleries of the museum are still 'specimen-rich', in other words a larger proportion of the collection is on public display than in most other museums.  Of particular note is the skeleton of a hippopotamus from nearby Barrington, and a full size model of the dinosaur iguanodon.

 Natural History Museum 

Cromwell Road,  London SW7 5BD.  Telephone: 020 7942 5000

The Natural History Museum's collection of fossils, comprising over 9 million specimens, needs no introduction.  On the ground floor of the museum is the British Geological Survey's London Information Office which sells geological maps and guides for the whole of the UK (open during office hours).

 Oxford University Museum of Natural History 
Parks Road,  Oxford OX1 3PW.  Telephone: 01865 272950

The Oxford University Museum of Natural History is renowned for its neo-gothic architecture.  It has a renowned fossil collection which icludes fine specimens of Oxfordshire dinosaurs.

 Ipswich Museum 
High Street, Ipswich IP1 3QH.  Telephone: 01473 433550

Ipswich Museum has important collections of fossils from East Anglia.  Of particular note is a full size model of a mammoth, complete with woolly coat.