Fossil hunting in Folkestone

In the first of a couple of very overdue posts, let me take you back to the end of May. The weather was beautiful and I was just starting out in the DNA lab. One weekend, me, some classmates and my not-biologist let's-see-what-all-the-fuss-is-about partner took a train to the south coast for a day of fossil hunting.

In previous years, my course had had a field trip to Folkestone, it being relatively close to London and very beginner-friendly. The main fossil formation is the Gault Clay, which is choc-a-block with marine inverts. But this year there were far too many of us. As it happens, I'd done an internship the other year curating Gault fossils with the highly knowledgeable Phil Hadland (https://sites.google.com/site/philhadland/ - I include a link because apparently Phil shares his name with a semi-famous footballer). Not only does he know his stuff, he's based in Folkestone and does guided walks. With his help, I organised an unofficial trip down anyway.

We started with a look around the brand new museum (http://www.folkestonemuseum.co.uk/), which had opened just the day before. It's a lovely space. While having lots of family-friendly interactives like all new galleries nowadays, it still managed to fit it a large number of specimens, especially for its size. We saw some spectacular examples of the sorts of fossils we'd be looking for.

After lunch on the beach in glorious sunshine, with a couple of my more daring colleagues taking a swim, we met up with our guide for the afternoon. I'd hoped that Phil could show us his local patch himself, but he was working in the museum, which understandably took priority! Instead we had Ian, another local fellow who'd been studying the area for most of his life, with an interest in butterflies and moths as well as fossils. We took the long way to the beach, taking in wildlife as we went. I think it's important for us to be naturalists as well as biologists. Biology is such a huge field, it's easy to get sucked into a speciality and forget that, for example, newts are awesome. I regret not getting a photo of the newt.

Ian gave us a short primer on the things we'd be looking for, aided by some of his own collection. Then we set out! The Gault Clay itself is at the back of the beach and fossils are eroded out and mixed in with the beach pebbles. Unfortunately, a combination of tides and trains meant we never managed to make it to 'the reef', his prime collecting site a bit further out, but for me just the beach was unbelievable.You'd look down and, underneath the top layer of large pebbles, every patch you dug through had something. I can see how people have spent their whole lives collecting there: there's just so much.

Towards the end, some of us scrambled around in the clay cliffs. The fossils are quite different up there. Because they've only just been exposed, the fragile parts remain; the downside is that a lot of the things you find are extremely fragile. One of us found a beautiful ammonite up there, nearly complete, but I'm just as happy with my pile of vaguely shell-shaped rocks that are more likely to withstand being forgotten about.

Gault fossils tend to come as these two main types. The prettiest are made of light grey clay with a fragile shell covering. The others are usually black phosphatised casts, where the original animal was buried but then dissolved away, with the space filled by another material. Casts aren't nearly so detailed but phosphate is nigh indestructible. However, beach fossils can also be made of pyrite. Pyrite reacts with oxygen in the air, especially humid air, to make sulphuric acid, which eventually eats the fossil, its label and quite possibly its container. Pyrite decay, as it's called, is unstoppable, but it can be delayed for a decade or so by painting clean fossils with clear nail varnish. Fortunately, most of mine are phosphate with just a lick of pyrite in some nooks and crannies, though even when I collected them those bits were orange with rust.

Anyway, here they are! I remember some names from when I studied Gault fossils with Phil, but most identifications were from this helpful website: http://www.gaultammonite.co.uk/
 

It's a shame it hasn't come out in the photo, but the two leftmost chunks are from the cliff clay and retain some iridescent aragonite.

Hamites is a genus of straight ammonite. These weren't coiled, but mostly U-shaped.

The other common cephalopods are the squid-like belemnites. The bullet-shaped parts are the equivalent of cuttlebones. This species comes in three varieties.

Occasionally there are more sedentary molluscs. This is a sea snail.

Even more molluscs: the most common beach fossils are inoceramid bivalves.

A similar species, but looking more like a toenail.

A mysterious one. I found non-inoceramid bivalves tricky to identify.

The two white fossils still have their chalky shells. The little black one is a phosphate cast.

Yep, not all corals form reefs. 100 million years ago, solitary corals were still in fashion.

Crinoids are like feathery starfish on a stalk. The fossil is a short segment of the stalk: a little stack of star-shaped ossicles.

Fossil serpulid worms are a bit of a mystery, because you really can't tell what the worms look like from their tubes, which is all that remains. Modern serpulids include the delightful Christmas tree worm: https://upload.wikimedia.org/wikipedia/commons/3/35/Have_a_Holly_Jolly_Christmas_Tree_Worm_%285287830740%29.jpg

Brachiopods, which look a lot like the totally-unrelated bivalves, are rare in the Gault. I've seen a round, teardrop-shaped one before, which is what might be inside this lump of very hard rock. But I don't think I'll ever get it out.

Finally, one for all you botanists out there. Wood isn't particularly rare, but it is often brittle and disintegrates easily. I was lucky to find a solid lump.