Humberside Geologist Online

Collecting Rocks, Minerals and Fossils in East Yorkshire

By Ros Perry

 

Where to Start:

The Holderness coast of East Yorkshire is an excellent place to start collecting rocks and fossils. The ice sheets, which once covered it, brought materials from the areas which they had passed over. When the ice eventually melted, around 14,500 years ago, it left behind the Boulder Clay that now covers Holderness. As the sea erodes the cliffs, it exposes the rocks and fossils that have been dumped in the Boulder Clay. This makes it possible to walk along the beach at, for example, Mappleton and pick up rocks, erratics, from other parts of northern Britain and Scandinavia for example: pieces of Shap Granite from Cumbria, coral limestone from Weardale, County Durham, and volcanic rocks from Norway. There are also fossils, such as ‘Devil’s Toe Nails’ (Gryphaea), perhaps 205 million years old, the bullet shaped belemnites, many of which are older than the Chalk cliffs (from around 135 million years ago), as well as ammonites and other shells.

N.B. You can pick up plenty of material from the beach, so you do not need to go close to the cliffs. If you want to go up to the base of the cliffs, you must wear a hard hat to protect your head from falling rock fragments. Never attempt to climb the cliffs – they are not safe.

Things to do before your Expedition:

1. Check the tide timetable. You should be on the beach at low tide. To avoid the risk of being trapped, aim to be there between 2 hours before and 2 hours after low tide.

2. Tell someone you know where you are going, when you will be there and, if possible, give them your mobile phone number.

3. Find out a bit about where you are going: visit the exhibition in The Treasure House, Beverley, http://www.eastriding.gov.uk/treasurehouse or The Hull and East Riding Museum in High Street, Hull http://www.hullcc.gov.uk/museums

4. Learn a little about the different types of rocks. There are many books, such as Yorkshire Rock, a journey through time by Richard Bell (British Geological Survey), which explains how rocks were laid down, and guides to rocks, minerals and fossils. An understanding of the different types of rocks and how they were formed will make it easier for you to identify your specimens.

Things to take with you:

1. A notebook and pencils to record useful information about what you find.

2. Some self sealing polythene bags and a labelling pen for your specimens.

3. Your mobile phone with a contact number.

4. A camera.

5. Some food and water and wipes to clean your hands.

6. A hard hat, if you are planning to go close to the cliff face.

7. You do not need a hammer, but if you take one, it must be a geological (not an ordinary) hammer and you should wear safety goggles when hammering.

8. Suitable clothing, footwear and sun screen.

When you arrive:

If you go to Mappleton, Withernsea or Hornsea you will see huge boulders near the cliffs which act as breakwaters. These hard, igneous rocks have been brought in, mainly from Norway, to protect the cliffs and to reduce the rate of erosion. If you are looking for specimens to collect, walk to beyond the area protected. (At Mappleton do not pick up any metal object which could be military ammunition).

As you are walking along the beach, you will notice the huge variety of rocks: colour, grain size, and shape; some may also contain fossils or parts of fossils. You may also be lucky enough to find loose fossils. Wet rocks look more attractive than when they have dried out! Remember other people will enjoy looking at them too, so photograph as much as you like, but only take home those you really want. You will also have to find space to store them.

Back Home:

Cleaning:

Wash the specimens to remove surface dirt and salt. Some, particularly fossils, may need further cleaning. An old toothbrush can be very helpful to remove mud. Avoid using any cleaning fluids apart from water and a drop of mild detergent, unless you can be sure they will not affect the specimen. Even vinegar will dissolve chalk.

(Hint: ask for permission at home to put your specimens in the cistern of your toilet. If you leave them in there for 2 to 3 weeks they will be flushed clean of salt water and so salt crystals, which can shatter your specimens, will not develop on drying out).

Fossil plant material is very easily damaged and it is best not to wash or treat the black carbonised leaves at all.

If the specimen appears to have a gold sparkle, it could contain iron pyrites, which in time will break down and release sulfuric acid and damage the specimen and its container. Unless you are able to keep this in a very dry environment, it would be wise to discard it or donate it to a museum where it can be properly curated.

Books and websites will explain how you can protect specimens, but remember that many varnishes and aerosols are permanent and will damage the specimen if they are removed later.

Label:

It is important to label where the specimens are from and any other information which you can find out about them. You never know, you may later find that you picked up something rare, and it would be very useful to you and possibly others to find out where it was from. It is a good idea to give each specimen a catalogue number, such as: place/year/ number: e.g. for the first specimen picked up at Mappleton in 2009: Mp/09/01. Put a small blob of acrylic paint on the specimen and then write on the code (or make a label card to keep with the specimen).

You should then record the number in a note book or on a computer spreadsheet and add additional information, such as:

Catalogue number

Location

Rock/Mineral/Fossil

Date found

Other useful information

         
         

 

If you cannot yet identify the rock / fossil – leave it blank, until you find out more.

If you have taken photographs, index them and where possible cross reference them with the specimens.

Store:

There are specially designed storage containers, or you may make something yourself. Try to make sure that the items are kept separately, so they do not get damaged by rubbing or scratching each other.

Identifying the Specimens:

Look at the colour, grain size and hardness of the specimen. If it was within the glacial ice, or has been carried by the tide, the shape is likely to be smooth and, if it is a mineral, such as quartz, it may appear dull.

You will see the grain size of many rocks more clearly with a hand lens or magnifying glass.

Remember other people are also fascinated by rocks, minerals and fossils and many have a great deal of knowledge and enthusiasm about their specialities, which they may share with you. You can ask the museums for help, or go to one of the Roadshows, organised by Hull Geological Society. The Society has a series of winter lectures and fieldtrips in the summer. If you are at all interested in finding out more and building your collection – why not join them or if you are still at school – contact Rockwatch ?

This is only an introduction to collecting specimens in a relatively safe public place, which is not a Site of Special Scientific Interest (SSSI) or Regionally Important Geological Site (RIGS). Please visit the website of Natural England for more information. Should you wish to collect in other places, you will need to find out whether collecting is permitted and to consider all aspects of safety.

Some useful websites:

Rockwatch is the club for young geologists, all those interested in things geological - rocks, fossils, minerals and landscape.

Hull Geological Society

Geologists' Association

Written by Ros Perry and adapted by the editors of the HGS

Copyright Hull Geological Society.

If you enjoy reading the article please conside joining the Society or sending a donation.

 

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