Explaining the planet’s history is really best left to the experts, but as one of the geological time periods is named after the county of Devon, I think it’s worth knowing how this occurred and how it all fits into the grand scheme of things.
To put it into some sort of perspective, geologists tell us that the earth was formed some 4,600 million years ago, with the oldest rocks in Britain being about 3,000 million years old (and found in North-Western Scotland). From this we can see that Devon’s beginnings don’t go back quite as far back as they might first appear, so why was the Devonian Period so named?
We only need to go back to the 1830s to find the answer. Up until that point, scientists from the early 18th century onwards were trying to map and categorize different geological time periods, and Roderick Murchison and Adam Sedgwick, two eminent members of the Geographical Society in London, had identified two separate eras which they called the Silurian and Carboniferous Periods.
This neat classification was thrown into some disarray when a colleague, Henry De la Beche, who was categorizing rocks himself in Devon, suggested there was also likely to be an intermediate period: The disagreement between the two parties led to the debate becoming known as the ‘Great Devonian Controversy’.
Paradoxically, it was Murchison who made the discoveries to prove that De la Beche was right all along. This intermediate era was determined to be between 359 and 419 million years ago, and was subsequently called the Devonian Period.
In the chart below, the Devonian Period is half-way down the Paleozoic column coloured brown.