Rock and Fossil Page
This page gives advice on how to preserve, display and record your speciemens. There is a frequently asked questions section and a section of the commonly found fossil speciemens (along with images as and when I can get the time to take them, and put them onto this site!)
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'How To' Guides
This section is intended to answer some of the more usual questions, and give a guide to the commonly seen fossils, to help you begin to identify your finds. This is not a full list of what may be found, it is intended as somewhere to begin, that is not too heavy on the science and classification, but gives enough information for you to carry your own researches forward, using more specific sites and books.
At the end of each section are some links to help you further.
Recording your finds
A collection of specimens has limited value in itself. The value (scientific) in a collection is the information that you record with the specimen, about where the specimen came from etc. The following pointers will help you achieve this.
When recording things in you field note book it is important to be accurate, it does not have to be neat, but legible! My Tutor gave me a good rule of thumb for what and how you record in your note book. “Write it so that another geologist can take your book into the field and see what you observed” Record what you can see as well as your interpretation but be careful to make clear which is evidence an which is not!
It is usual to record where and when you found your specimen (the local name of the area is fine – better is the ordnance survey grid reference (6 figure is fine, 8 figure is better), the identification of the specimen and what rock formation you found it in etc. Try to be as accurate as you can, but if you do not know any of the information, do not worry it is often possible to find out that information later (take photographs!).
Write the information in three places – in your notebook, on a slip of paper you can out in the bag with your specimen and write it on the bag you have put your specimen in. This information can form the basis of a catalogue of your finds (a useful thing to do if you cannot go collecting! (for any reason!)).
In summary
- Please do not trust to memory – it often fails! Write everything down in a field note book.
- If you do not know what the rock formations are – take a sample of it (if allowed) and photograph the formations for later identification.
- Information to note down:
(Kept with specimen)
Date of collection
Location (name & O/S grid reference)
Specimen name (if known)
Specimen Reference number
(In note book)
Rock in which specimen found (if known)
Description of specimen and rock in which found
Drawing of exposure
Note down any other pertinent points
Specimen Reference number
Fossil Specimen Preservation
A word of warning! Because of the nature of fossils and the various minerals etc that may be contained within them, we can accept no liability for your fossils if you choose our method of preserving them. We recommend you research other methods that you may feel are better or that you feel more comfortable carrying out. If in doubt do not collect these fossil types – photograph and leave them where you found them.
Having issued this dire warning – most fossils need no special actions to preserve them!
Having found some fossils you will wish to preserve them and perhaps mount them for display. The first step is to preserve the specimen.
Although many fossils do not require much in the way of preservation, some do. Usually it is the mineral, minerals or rock type that is unstable and requires a little assistance to remain whole. In some cases just drying out is the answer, in others soaking in fresh water and sealing against the atmosphere is necessary. This list, below gives some advice on the commonly found problems. Preserving fossils is not an exact science, and things can go horribly wrong, even to the experts, so before embarking of any such action as those described below I strongly recommend that you photograph the fossil – just in case!
Clay
Specimens found in clays tend to be very fragile. If the clay has hardened over geological time, then all that is required is to allow any moisture to evaporate (the time this takes depends on the size of the specimen and the block of clay that contains it). Even when dry, clays tend to crumble. So I paint the matrix that my specimens are held in with a couple of coats of PVA glue (a 50/50 mix with water) allowing the specimens to dry thoroughly between coats. To preserve the specimen itself I use an artists varnish (that is easily removes later on if required). If any large cracks appear in the clay, these may be stabilised with superglue. Whatever you do Do Not soak this type of specimen in water – it will fall to pieces and turn back to mud before your eyes!
Poorly cemented sandstones.
I treat this in the same way as clay fossils. Even so they still tend to be very fragile, so it is best to handle them as little as possible.
Specimens with high iron pyrites content
This one is an absolute headache! Even with the best systems available these fossils have a disturbing and disagreeable habit of dissolving themselves! The problem is the iron pyrites. On contact with atmospheric conditions the iron pyrites turns to sulphuric acid and the fossil self-decays over a period of a few years.
There is no sure-fire way of preventing this; the best that can be done is to soak the fossil in fresh water. When you do this you will see tiny bubbles coming from your fossil. This is the iron pyrites turning to sulphuric acid and dissolving the fossil. Don’t panic! Change the water every day. When the bubbles stop appearing, remove the fossil from the water and allow it to dry thoroughly. Then coat with neat PVA glue or a waterproof clear varnish (matt is recommended) then when dry, place the fossil in an airtight container with a small bag of silica gel (the little bags that arrive in the packaging of electrical goods etc).
This will probably not completely solve the problem, but it will slow it down to a manageable level! Even so, inspect this type of fossil regularly and take remedial action.
Displaying your specimens
There are available stands, mounts, plastic boxes with and without magnifying lids, and they are not expensive. There is. of course a more expensive option - glass display cobinet too! These all have their place in storage and preserving your fossils. If you intend to display your fossils, please do not glue them to a board or into a display box or case. This will detract from you fossil – and if you need to take action later on to repair or conserve the fossil you will find it difficult to remove the fossil without damaging it further.
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Frequently Asked Fossil Questions
Q. What is a fossil?
Answer: Fossils are the impressions of past life. These life forms may be extinct, or there may still be living relatives of them. Fossils occur as two types - body or trace:
Body fossils are the preserved remains of an organism’s body, skeleton or any part of its body or skeleton. Trace fossils are the preserved remains of traces of the animal, for example footprints, track ways burrows, coprolites (faeces) etc.
Q. How do they form and why are bones and shells preserved , not the whole animal?
Answer: Fossils form when an animal or plant dies, is then rapidly buried by sediments. Minerals from the sediments that covered them then replace the organic parts of the plant or animal, effectively turning them to stone. This is called diagensis. This process usually happens to the harder parts of animals and plants (the soft parts of an organism are very rarely preserved!). Because then, as now, when something dies - there are always scavangers about ready to grab an easy meal! So the soft parts of the organisms either rapidly rotted away (or were eaten by something) before the fossilisation process could be completed. What must be remembered is that fossilisation is a vary rare process. It is estimated that about 1% of everything that has lived, has been fossilised
Q. How old are they?
Answer:This is like asking how long is a piece of string! Fossils can be thousands, tens of thousands or even thousands of millions of years old. It all depends! Fossils represent the evolution of life on Earth. This has been going on for the last 3.8 billion years, so you will find fossils of all ages!
Q. Why are shells the most common fossil found?
Answer: In the geological past, as now, the most numerous animals around (except things like plankton etc.) were the molluscs. The more numerous an animal is, the higher the chance of it being fossilised are, and molluscs live in places where muds, clays etc are common, and these are the best rock types to preserve animals and plants. So it follows that molluscs are the most common fossils to be found because there was a lot of them and they lived in places that favoured preservation.
Q. Why are the complete skeletons of animals such as dinosaurs not often found?
Answer: Once again we can draw parallels with modern animal life. Consider the plains of Africa. When an animal dies, there are many scavangers around to make use of a free meal. These scavangers include vultures, hyenas, and lions. These animals will waste nothing, even the hide and bones are eaten (to a greater or lesser extent) and as the carcass in consumed the bones that are left become scattered across the local landscape.
This process also ocurred in geological history. Animals such as Allosaurus and Tryannosurus Rex appear not to have passed up the chance of an easy meal. These two top end predators were not the only animals to be involved in clear up operations, there were many smaller species of dinosaur that specialised in scavanging.
So it is usual to find bits of bone, scattered around, not as a 'fully or partially articulated' skeleton.In fact is is very rare to find a whole skeleton of an animal such as a dinosaur etc. preserved in the ground!
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Common Fossil Types
(images of various species will appear as I take them - please be patient!)
Invertibrates (animals without backbones)
Crusteacea Most fossils of this group pass by un-noticed as they are small.
Ostracoda. Ostracods, these are small (no larger than 2mm) crustaceans. They still are alive today!
Lobsters and Crabs. These animals appear in the fossil record much as they do today!
Molluscs The comonest and most numerous fossils are of animals that lived in shells.
Ammonoids.This is a group of the molluscs known as the cephalapods (modern species in this group include octopus, squid and nautilus).The ammonoids contain groups of animals such as the ammonites, scaphopods, hamites, nautiloids and belemnites.
Hamites - a straight, uncoiled species of ammonoid
Ammonite fragments - unknown species
Bivalves. These molluscs are characterised by having two valves of their shells mirror images of each other (modern species include mussels and cockles).
Brachiopods.These are molluscs again (a big group of aminals in the past, as they are now!).These animals have two valves to their shells, except the valves are not miror images of each other - they are different in both size and shape (there are few modern species left).
Gastropods.These molluscs are commonly called 'snails'. They are characterised by having a spiral shell, with one whorl laid onto the previous one (modern species include the garden snail, whelks and winkles).
Vertibrates (animals with backbones)
Rib - unknown vertibrate species
Pisces (fish). This ancient group of animals reached their peak in the Devonian.Pisces are divided into two groups:
Elasmobranchs (cartiaginous fish) such as the sharks and rays.
Telesotomi (bony fish) which are all the rest!
Reptillia This large group of ancient animals are famous for the dinsaurs.
Dinosauria. Dinosaurs were all land living, they did not fly, they had specialised hips that allowed them to walk and run both on four legs as well as two. However as there are around 1500 species of dinosaur recorded. It would be a folly to try to list them all here. It is best to look t the Natural History Museum website where there is an excellent resource for all dinosaurs.
Chelonia. Tortoises and turtles. These are usually seen in the fossil record as fossiled scutes (panels of their shells).
Crocodillia. Crocodiles and Alligators. Usually onle seen in the fossil record from the presence of their teeth.
Marine Reptiles. This is a big group. It contains animals such as the Ichthyosaur (a dolphin looking reptile) to the plesiosaurs and pliosaurs which grew to massive sizes. Usually only fragments of bone are found (and they are easy to miss too!)
Flying Reptiles. Another large group of ancient reptiles. These contain the pterosaurs. they are usually only found as bone fragments (and these are very delicate so if you are lucky enough to find some - treat the with care!)
This Section is Under Construction