Fossil Hunting in Whitby

Fossil hunting feels pretty much the same as hunting for treasure. I see pictures of fossils on the internet, or in shops, and think - I want to find something as good as that. The lack of fossils sold of UK origin, and my assumption that most fossils and minerals are dug up during the quarrying process gives the impression that spectacular finds cannot be made by amateurs. However, this is not the case, especially if hunting happens at the right time, at the right place with the correct equipment.

To get a good idea of where to go, and what the location is like the following website is excellent: http://www.ukfossils.co.uk/

I went fossil hunting to Whitby with a group of work mates about a month ago. Winter is one of the best times to go to fossil hunting in coastal locations because the seas are stormier and so erode the cliffs and foreshore more. There is also more rain. Rainwater gets into the rock and acts as a lubricant along fractures. It reduces friction allowing the rock to more easily slip along planes of weakness, causing bits of rock to fall into the sea. These can range from small bits of loose rock falling off to big landslides. The rocky material contains fossils, which have now moved from the cliffs to the beach, where we can get to it. This is great for fossil lovers but not great from a health and safety point of view. I have seen rocks fall from the top of the cliffs at Whitby and so hard hats are a good option if you wish to search near the base of the cliffs.

The foreshore

                                        

When we got to Whitby, we turned right at the harbour onto the coast. We looked up the tide times beforehand. It is best to start as the sea is going out, especially as there is only about a 2 (possibly 3) hour window to access that side of the bay without being covered in water. The sea reaches quite high along the cliffs and the coastline forms a series of bays, which makes it hard to see how far the tide has come in. The tide also moves quickly, so it is important to keep an eye on it.

As we walked along the foreshore, we saw that it was covered with fossilised ammonites, belemites and small bivalves. There were also some loose ammonites, but these were harder to find, and we should have probably walked further along the coast before starting our search. We also found fossil plant material and some coal. Reptile remains and also jet can also be found, although we were not lucky enough to find these. Jet is formed from the fossilised remains of Araucaria trees – similar to Monkey Puzzle trees, and Whitby is famous for it. Whitby jet – as it is known is used as a stone for making jewellery because it is dark and shiny.

Below is a sample of our fossil finds:

Belemnite

Belemnite

Belemnite

Ammonite: Hildoceras bifrons

Ammonite

Ammonite

Plant: Coniopteris hymenophylloides????

Plant material

Coal???

What the rocks and fossils of the cliff tell us about what the environment was like when the material that made them was first put there.

The cliffs at Whitby are of Lower and early middle Jurassic age (188-175Ma). The fossils in the cliff can be used to date its age. This is because, due to evolution, different types of fossils are only found for a certain period of geological time.

For example, the Hildoceras birons – the (first ammonite shown above), is only found within a specific band of time within the lower Jurassic. This time marks the period between its first appearance (which we assume is ‘close’ to when this  organism first evolved) to when it became extinct; 175 million years ago.

From the cliff’s rock type, study of the surrounding area and previous geological knowledge geologists can tell that the cliffs were laid down in waters that reached at greatest, depths of 200m. It was part of the continental shelf and plant material was swept into the environment from huge rivers running off the continent. The Whitby area became shallower (with deeper dips also forming) as the sea surface became buckled as two land areas moved towards each other in the process that formed the Alps. This gives us rocks that were formed in erosive, marine, and deltaic environments.

Identifying fossils

Obviously indentifying fossils is not essential, but it is a nice geeky extra. Judging by the huge range of organisms on the planet in present day, I do not know how one book can have all the fossils found in the UK in it. However, I have been using a book called “British Mesozoic fossils” made by the Natural History Museum and this has proved useful.