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Due to a pleasant change in my circumstances, I have been to Lyme Regis several times recently, and it seems as though I'm going to be a regular visitor over the next few years.

As a former biologist I found the experience of combing the shore of the famous Jurassic coast for fossils to be delightfully addictive. Having spent about six hours over three days doing so, I've amassed a decent collection of ammonite fragments. Having got the bug for doing this, I'm eager to try and find some more impressive specimens.

Chatting to some of the local palaeontologists on the beach it became apparent that to do so you need to split rocks, and that you need to know which rocks to split. It's also clear to me that while I've become attuned to watching for the shapes and patterns indicative of ammonites, I don't yet have the eye for the other colours and shapes of fossil shells and bones.

I tried to do some reading about the geology of the region, but most of what I found online was either too basic (i.e. aimed at non-scientists) or too advanced (i.e. aimed at actual geologists) for me.

So: how can I learn to better spot fossils and fossil bearing rocks in this region? I'd be very interested to learn some geology if it would help, but if that's the case, how can I find material pitched to the right level?

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  • $\begingroup$ Did you see discoveringfossils.co.uk/fossil_hunting_guide.htm ? $\endgroup$ – Jan Doggen Jun 2 '15 at 7:44
  • $\begingroup$ And did you google detecting fossils? $\endgroup$ – Jan Doggen Jun 2 '15 at 7:46
  • $\begingroup$ Additionally, on the website of the university of Southampton, you can find a little geologic field guide for the coast around Lyme Regis that might be handy: southampton.ac.uk/~imw/Lyme-Regis-to-Charmouth.htm . They have some geological maps of the area that can help you find spots of interest. $\endgroup$ – plannapus Jun 2 '15 at 7:51
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    $\begingroup$ @JanDoggen I have seen that link amongst my searching. The trouble is that it, along with the majority of what I found, contains little practical advice. Skilled fossil hunters can pick up a rock on the beach knowing there's already a strong chance it contains a fossil from its geology alone. That's the key skill I'm keen to learn. Exposed fossils amongst the rocks are almost always fragmentary or worn. $\endgroup$ – Bob Tway Jun 2 '15 at 13:01
  • $\begingroup$ @plannapus The fossils are largely marine invertebrates (shelled cephalopods, bivavles, crinoids etc), fish and marine reptiles. $\endgroup$ – Bob Tway Jun 2 '15 at 13:03
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You are correct when you say it is mostly a matter of getting your eye in and getting used to the shapes and types of rock you need to be looking at. Hopefully however the below information will help you find a few more fossils or at least be of interest to you.

The main fossil bearing beds in Lyme Regis are from the Jurassic period and formed in a warm sea, hence the marine fossils.The Jurassic strata (layers of rock) in this area are mainly composed of grey limestones, shales and marls (lime rich mudstones). These are the rocks you want to focus on when searching for fossils (see image below taken facing church cliffs).

enter image description here

The majority of the very well preserved ammonites are found in the limestone and can be found inside limestone nodules or lying loose on the beach. This rock is very hard and will require a good geological hammer and maybe a chisel to split. This is often easiest if you find a nodule with lines of weakness or cracks that you can split it along. It is also a good idea to look for signs that the rock contains a fossil before trying to break it, part of a fossil may be visible on the surface of the rock.

You can identify the limestone by it's lighter grey colour and hardness, it should be quite hard to break without a hammer.

enter image description here

It is however possible to find ammonites in the shale and mudstones, the ammonites in these however tend to be less well preserved. These rocks are typically a darker grey and very easy to break. However there are other fossils that can be found in these shales, including belemnite rostrum (belemnite guards). These bullet shaped fossils are from an ancient relative of the squid and the cuttlefish and are very abundant in certain areas.

Finally there are very soft mudstone beds out near Church Cliffs that you can walk across along the foreshore and are rich in belemnites, as well as pyrite (fools gold) and pyritised ammonites. These are formed when the original shell is replaced by pyrite in low oxygen conditions such as deep on a muddy sea floor and can be recognised by their golden colour and shine.

All the best with your fossil hunting!

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As a very general rule, I'd look for rocks deposited in low energy environment, e.g. shale and some carbonates. Waves often destroys remains of animals in sand, so massive sandstones wouldn't be my first place to look. When you find one fossil, continue to look in the same layer.

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