On a May weekend last year I travelled to Shropshire to tryand scratch an old itch of mine which was to find atrilobite. I already have a couple of examples (Calymeneand Eltrathia) which I received as a present bought fromthe Lyme Regis fossil shop, but nothing compares toactually finding the specimens yourself. Words likecontext and provenance spring to mind along with morepersonal ones like satisfaction and achievement. I had livedin Shropshire previous to moving to the Bath area and hadeven tried to find trilobites on my own a couple of times.This involved locating disused quarries on the map fromaround the Wrekin area and then if possible having a look.Like most things, if I were looking for rusty old farmmachinery and sheep carcasses, I’d have found loads oftrilobite fossils. As it was, the itch remained unscratched.

Moving on some eight years and now as a new member ofthe Bath Geological Society, I became aware of anothersociety (the Essex Rock and Mineral Society - ERMS forshort) who were planning a trip to Shropshire to look fortrilobites. I contacted their field trip organiser and arrangedto join the hunt. I had thought of exploiting the fact thatBath Geological Society has the same initials as the BritishGeological Survey by saying something like ‘Hello, Brownhere, from the BGS’. Which I thought sounded very grandand although strictly true I was concerned that any falseassumptions derived would be quickly discovered on theactual trip through my obvious lack of knowledge andperplexed expression at most things geological.

This then is my personal recollection of the weekendextracted from an all too fallible memory. It is intendedmore to divert rather than inform, mainly to hide myignorance of the subject. Hopefully, it contains enoughtechnical stuff not to be burnt on sight by the moreacademic members of the society, but I give no promises.

The first site on the Saturday was called Overtons Rough,(photograph 1).

The rocks were wet crumbly shales laid down in deepwater sometime in the Ordovician. Finds were scarce but Idid manage to find a rather distorted fossil. The distortion,I assume, is due to folding activity sometime in the 460odd million years it’s been lying around waiting forsomebody to find it. However I was told subsequently thatit could have been caused by the fossilisation process(compaction and lithification); one way to get furtheruseful information would be from a petrologicalexamination in thin section. I’ve no resources for such anactivity and as it was my first find, I had very littlemotivation to destroy it even if I had. It may be distorted,but I had a feeling that I hoped I looked that good after thebest part of half a billion years.

As for what it is, when I showed it to Bob Kennedy (fromBirmingham Museum and the trip leader) he reeled off astring of words within which I believe I heard the nameCalymene. Looking in the Natural History Museum’sBritish Palaeozoic Fossils yields the prefix Flexi- or Platy-for Calymene in the Ordovician. Unfortunately, thespecimen is so poor it is hard to make a closeridentification. If forced, I’d say Flexicalymene caractaci,(photograph 2).

An interesting event occurred whilst photographing thefossil as it literally crumbled in my hands. This was thecause of great consternation on my part as I had forgottenthe advice given on the trip to prepare the samples as theywould crumble when they dried out. However, after givingmyself a good tongue lashing for being so forgetful andlazy with a few adjectives best left out of a printed journal,I found that the crumbling had occurred around the fossilitself. The shape of it had introduced a natural weakness inthe shale which the fractures had followed. This resulted ina 3D shape partly appearing on one side and the hope onmy part that the fossil might be whole and not ascompacted as the majority of fossils I found over that

Journal of the Bath Geological Society, No. 23, 200424

IN SEARCH OF A TRILOBITEIain Brown

Photograph 1: Overtons Rough

Photograph 2: Flexicalymene caractaci?

weekend. These specimens were mainly in harder, slatetype rocks so compaction and metamorphism would tendto make them much more two dimensional (see later

photos). A case of beginner’s luck had improved thefossil. I’ve also now treated it with a PVA solution so itshould not crumble any further.

The second site on the first day was Deltons Wood where,as mentioned earlier, the rocks are hard and slate like. Thissite proved the most productive of the weekend for me, foran unusual reason. As the rocks were very hard I managedto split the handle of the hammer I was using as myenthusiasm outweighed my skill (some unkind souls mayeven say brawn outweighed brain). However, hammerless,I was forced to scavenge around in the loose stuff for finds.Gleaning this way proved a very successful method ofcollecting for somebody who was not too fussy about thequality of fossils found. Even sitting down, the rockswithin arm’s reach would yield a large number of fossils.The vast majority of these specimens were fragments oftrilobites which may not have been good enough for theperson who discarded the rock in the first place, but as thiswas my first trip, I was delighted with finding them.

One find showed the thorax and tail piece (pygidium) of, Ibelieve, Ogygiocarella (Oggy to its friends). Below is anexample of the top part of an Oggy. It shows the glabellaand about 6 segments of the thorax. The glabella is thecentral raised part of the trilobite head (note:- the specimenis the negative half of the fossil so here shows as adepression). The complete head shield of a trilobite iscalled the cephalon. My specimen hasn’t got the fullcephalon as it is lacking bits called cheeks (free and fixed)which lie either side of the glabella, (photograph 3).

Another species of trilobite that was common was Onnia,photograph 4.

One specimen was tiny but one of the very few completeexamples I found. As trilobites shed their hard shells toenable growth (much like modern day lobsters and crabs)finding pieces of shell is very common. Photograph 4

shows a bigger example and though also complete it ispartially obscured by the head shield of another.

If you look closely at this photograph you may just makeout the genal spine which Onnia has extending from thehead shield down parallel to the thorax. Also the curiousrows of ‘dots’ or pits on the head shield which, in life,were some kind of sensory device.

The second day started at Acton Scott, which represented adifferent environment back in the Ordovician. The othersites on the first day were what Bob called ‘lifeassemblages’ which means the animals actually lived (anddied) locally. Acton Scott was a calcareous mudstone andrepresented a site where various animal parts wouldcongregate through wave action or gravity after death. Thismeant the chances of a complete trilobite were small.However, this was offset by the chance of finding othertypes of fossil.

Photograph 5 is a specimen from Acton Scott and shows ahead shield of Calymene (again) with other fossils aroundit.

Photograph 6 is the reverse of the same piece of rock andshows an abundance of Ordovician brachiopods with aboutfour types in evidence. Also of interest is the five pointedstar just below the centre line on the right which I assumeis a crinoid fragment (ossicle).

Journal of the Bath Geological Society, No. 23, 2004 25

Photograph 3: Trilobite cephalon

Photograph 4: Onnia

Photograph 5: Calymene and others

The last site of the weekend was in the River Onny,photograph 7, and I do mean in. After Bob had told us thecolour of the rocks to look out for and the sound they madewhen struck by a hammer we had to locate the rocks in theriver bed. Despite Bob’s guidance I was unable to find anyfossils but enjoyed myself none the less. There’ssomething delightfully childish about splashing about asmall river bed. For those who do not know me by sight,I’m the one in the rather fetching boiler suit* withmatching accessories reaching for the pick-axe. (*It’s sky-blue by the way! - Ed)

The Onny site is of special geological interest as it containsan unconformity which is believed to have misledMurchison, leading to a disagreement with his then friendSedgwick after they had published their Silurian andCambrian systems (1835). As can be seen in photograph 8,

where Bob is indicating the approximate horizon of theunconformity, the dip is very similar. As most of theOrdovician is missing, this led Murchison to make somefalse conclusions from his study of the fossils found in thestrata. The controversy was resolved when Lapworthsuggested the Ordovician series (~1880).

So, wet and tired, with pockets full of bits of rock, theweekend trip came to an end. For me, the trilobite itch hadbeen well and truly scratched, though at that time, I did notknow that the relief would prove temporary. Hopefully,this year I can do some more scratching.

Readers of the freebie tabloid the Metro have known sinceMay 13th that the Vendian period has been re-named theEdiacaran by the International Commission onStratigraphy. Under the page-top headline ‘600m-YEARWAIT TO BE NAMED IS OVER’ were three, yes three,columns on this story with a stratigraphic column in colouralongside. There is the Ediacaran, below the Cambrian at545-600 m.y., marked by the ‘appearance of complexmulti-cellular life-worms, jellyfish etc’. Life-worms?

We were told the re-naming had taken 15 years and threeballots of ‘the world’s top geologists’. Also that theRussians were upset, deeply upset. Expert Boris Sokolovwas wheeled out to tell us why. This was drama. There wasno trace of tongue-in-cheek, and anyway, why pick on theICS?

So stratigraphy has made it into the tabloid press. Well,the Metro anyway. You know the Metro? It’s what formsmost of the layer of paper covering the floor and seats ofthe tube trains when you get to London mid-morning onyour off-peak day-return and the commuters have all goneto their offices. And now I see it’s appearing on Bathbuses; so a genuine national daily.

But; a small but, even the reporter seems to have haddoubts about the interest this news would generate on theBakerloo Line. At one point she admonishes the bleary-eyed traveller: ‘Stay awake at the back!’

So what is going on? Is the editor of the Metro keen topromote geology? Or does he think the cold war rumbleson in some sinister fashion in scientific circles? Perhapsthe reporter made a bet in the newsroom she could makeanything interesting to the average newspaper reader, (inwhich case she probably lost).

Journal of the Bath Geological Society, No. 23, 200426

Photograph 6: Brachiopods plus crinoid fragment

Photograph 7: River Onny

Photograph 8: Controversial unconformity

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