Aug 20, 20233 min read

Fossils lost and found

Have you ever brought home an unusual looking stone from the beach? I have, and some are more than just stones, some are fossilised remains of creatures that lived there more than 50 million years ago. Every single flint pebble on the beach has fallen out of the chalk cliffs along the southern English coast and basically, is in fact the fossilised remains of rotten seaweed that settled on the bottom of an ancient sea in layers every few million years, along with long lost creatures such as Sea Urchins.

Let's go back a wee bit in time. 50,000,000 yrs is a long time for us bit in the vastness of time it's just a blip. What you are looking at in the photo below is a slice of the ocean floor that was pushed up and out of the water by earth quakes and tectonic plate movements as far away as The Himalaya's.

The bottom of this cliff is approx. 90 million years old and the top 50 million. The chalk is the remains of plankton that died and fell to the bottom of that primeval sea and as today's weather gradually erodes the cliff those lost fossils can be found. I'll show you some that I have bought home.

Here is a Scallop shell in chalk, two types of sea urchins in flint and an Ammonite in chalk. Let me show you some more urchins and a top tip you might like to try for display a collection...

So, let's look closely at the two urchins below.

Left is an example preserved in chalk and Right is one in Flint. The mail difference is that the one on the right has had its shell worn off by being accidently tumbled in amongst the other pebbles on the beach and the one on the left has been dug out of a fallen chalk block before the somewhat delicate 'shell' was destroyed by wave action. By the way, the pattern on the flint urchin is of course the pattern of the inside of the original shell.

There is something else interesting to see here, remember my grandads words;

"Don't just look at things, 'see' them"

What we are looking at here is the under sides of these two urchins. The holes at the top of both photos are the urchins mouths, At the bottom of the chalk example and the centre of the flint one are their 'bottoms'. ( Kids love this story ) So, what do we 'see' ?

The flint one has his bum closer to his mouth than the chalk one. These creatures were evolving from something similar to a starfish and over those millions of years, folded it's appendages in to become the urchins that exists today which accidentally drew it bottom closer to it's mouth. The flint example is the new kid in town, fallen from the top of the cliff, preserved approx. 50 million years go, the chalk fellow from the bottom of the cliff approx. 90 million yrs old.

My favourite type of sea urchin fossils are those partially preserved in the flint layers. Exactly what the flint layer is I'm not sure anyone truly knows but it can make great display pieces. on the left an example I found that had been in the inter-tidal area for a while and the outer shell had been worn off and the one on the right had freshly broken out of a block of chalk and flint in a rockfall with its shell 90% complete. If you prefer or want one of each in a display, there is a way to get that shell off.