The Prehistory of the World in Welsh Tribes and Chalk

What's in a name? Why do certain phenomena have certain names? To my mind, one of the most fascinating and idiosyncratic naming processes was that of naming the periods in prehistory up to the end of the dinosaurs: Cambrian, Devonian, Silurian, Ordivician, Permian, Triassic, Jurassic and Cretaceous. Generations of palaeontologists, geologists, bonehunters and schoolchildren have had them rolling off their tongues, probably with no real idea of how these names actually came about, what they're named after, and how the names have resonated in time.

So, how did these periods get their names? Clearly, the people who researched these times over the last couple of hundred years, after interest in the prehistory of the world really took off, had their own favoured naming strategies. Let's start at the beginning, quite literally

The first period of the Palaeozoic Era, literally “ancient-life era”, was the Cambrian period, from about 541m to 485m years ago. It was characterised by the first explosion of multi-cellular life forms, the fossils of which were first found in rocks in Wales, known as Cambria in Latin, and Cymru (pronounced “come-ree”) in modern Welsh, ultimately from an ancient British form meaning “fellow countrymen”.

The Cambrian was followed by the Ordivician, which lasted until about 443m years ago. The Ordivices were a Celtic tribe living in North Wales and conquered by the Romans in 77-78CE. Their name was applied to the period whose rocks mostly appeared in their territory. The Ordivician was followed by the Silurian period, lasting till about 419m years ago, the Silures being a tribe living around South Wales and the English borders, where the rocks from that era predominated. Strangely, the use of Silurian to describe an ancient race of human-like reptiles in Doctor Who is inappropriate, not because the Welsh tribe actually consisted of humans as opposed to reptiles, but because no reptiles existed at the time, the most dominant life forms being early bony fish and giant sea scorpions

So far, so Welsh. For the next period, we have to move south, across the Bristol Channel. The Devonian period lasted till around 359m years ago, and was named, surprisingly enough, after Devon, where such rocks abound. However, Devon gets its name from the Dumnonii, a Celtic tribe which occupied the furthest south-western region of Britain, so in essence, they were an extension of the Welsh. So there we have it; the first four Palaeozoic periods named effectively after ancient British tribes.

So what of the next one? Was there a tribe called the Carboniferi? No. The Carboniferous period, which lasted till about 299m years ago, literally means “carbon-bearing”, because this was the period when huge forests dominated the land and were transformed over time into the coal that fuelled the industrial revolution. This was followed by the Permian period, the last of the Palaeozoic, lasting till about 252m years ago. So, who were the Perms, actually, Permians, and how were they related to the Welsh tribes? Well, they weren't. Permia was a medieval kingdom on the western slopes of the Urals in Russia and gave its name to the age as a result of the rocks found there which dated from that era

The Mesozoic, or Middle Life, Era is probably the most famous in prehistory, mainly because it was the period of the dinosaurs. The first of the three Mesozoic periods was the Triassic, running till about 200m years ago and named after the three-colour rock formations, black on white on red, which were found mainly in Germany. Then the most famous period, the Jurassic, followed, lasting till about 145m years ago and named after the Jura mountains straddling the French-Swiss border. The third and last period, lasting till the end of the dinosaurs about 66m years ago, was the Cretaceous, named after the Latin for chalk, creta, which was laid down in western Europe in the shallow seas of this period.

So, there we have it: Wales and two of its tribes, an ancient west country tribe, bearers of carbon, a province in Russia, three German rock layers, French/Swiss mountains and western European chalk; a motley and varied crew defining almost 500m years of prehistory, named mostly according to the personal whims of the geologists who defined them. And if you look into virtually any other area of science, you will find remarkably similar stories.