Charmouth

On Saturday, my host family for next year invited me on a trip to Charmouth, one of the beaches along the Jurassic Coast – a stretch of the southern coast where there are plenty of Jurassic marine fossils. Charmouth is next to Lyme Regis, the famous site where Mary Anning found a vast wealth of ichthyosaur fossils, which we also visited later.

The weather was spectacular, the scenery mesmerising, and we had great fun. However, we hardly found any fossils at all! Only the eldest daughter found one finger-sized piece that definitely was a fossil (maybe a bit of a coral), and also I saw this gastropod impression in a large rock on the shore.

So, this post might turn out quite strange: the story of various things I hope are some sort of fossils, and if (or if not), I have no clue of what…

But first, some of the fun we had:

The beach was full of ‘egg fossils’, many of which were ready to ‘hatch’.

There was plenty of marl (a very fine-grained calcium carbonate sedimentary rock, much like limestone but muddier, i.e. smaller grains) that was so soft that one could easily make markings with a harder rock. We seized this excellent opportunity to prank other fossil hunters by carving in things like (my artistic interpretation of) the Transformers emblem, and this:

At Lyme Regis, on the dock wall, there was a large mat of a fossil bryozoan colony:

(well, not really, but I like to think it was…)

Now to the ‘fossils’ I brought back home. (I apologise for the strange structure of this post, but I found no sensible way of organising this… the fossils were, after all, secondary – the most important thing was to have a good time with the people I am living with next year!)


Cephalisation is the fancy term for the evolution of a head. In practice, it involves the development of a sophisticated nervous centre and the concentration of certain sensory organs (eyes, nose, ears) at the front end of the animal. This is prominent in higher animals such as vertebrates (or, to be specific, craniates – chordates with a skull, which includes vertebrates and hagfish) and arthropods, in particular insects. This spectacular specimen, however, has two faces:

 

I’m not kidding, it is the same rock!

Now, to the more serious fossil candidates… these fairly regular imprints on a rock could be from an ammonoid or nautiloid cephalopod shell that maybe just landed in the sediment and made a mark.

However, the irregular spacing between the indentations makes me wonder if it really could be so…

There was plenty of flint on the beach, and many had really odd shapes, while a few looked a bit like corals:

But, as you can see, only the overall shape is reminiscent of a rugose coral; there are no characteristic markings or other signs that this was an actual living organism once. Moreover, flint is made of silica, while coral skeletons were made of calcite, so I am more inclined to think that these are not true fossils, but just lumps of flint that happen to look like it.

The next rock has two rather odd… thingies… on it.

I frankly have no clue of what any of those could be.

Finally, one rock had three rather peculiar ring-like marks, two of which are fused together into what looks like a pair of goggles.

The outer rim seems to be made of at least three layers, the inner being darker than the other two. These circles are infilled with another different material, probably one that is less weathering-resistant, since the centre makes a bowl-like depression in one of them.

The round shape, the weaker core and the onion-like outer layers bring my thoughts to ooids, strange, poorly understood sedimentary structures that might have been formed by layers of carbonate deposited on a rounded rock grain core in an environment where waves would have rolled it around giving it a nice round, smooth shape. However, I am not sure if ooids can be this large (1-1.5 cm across). If these are ooids, though, it means they are not fossils, sadly.

If these would be fossils, I can only imagine that they would be some form of microbial colonies, and perhaps the different layers point toward some sort of differentiation (different cells in the colony performing different tasks)? Maybe? Maaaybe…?