Geological Ages

A new year and, unlike the Chinese calendar, it doesn't have a name but a number. Remember the good old days before humanity took over the planet when great beasts roamed the land or earlier still when no life-form on the planet existed unless it was single celled? No? In those days at least they had the good sense to give the eons names instead of numbers.

Precambrian is, well, as the name suggests tha which came before the Cambrian. Not overly imaginative you would think but it does cover four billion years from the start of the planet up to 541 million years ago. Credit should also be given to correctly forecasting the name given to the following eon, the Cambrian.

Cambrian was coined by Adam Sedgwick, who named the period of 541 to 485 million years ago after the Latinised form of Cymru, the Welsh name for Wales as this is where he felt the rocks from this time were best exposed. The Welsh Cymry, the word for the people of Cymru, means 'fellow countrymen', rather different from the Saxon wahl from which comes the name of Wales which meant 'foreigner', although this could hardly be considered xenophobic as all the Saxons were saying was they were not Saxon.

Ordovician is named after the Celtic Ordovices, as chosen by Charles Lapworth in 1879, to describe the period from 485 to 443 million years ago. The Ordovices may have farmed the land and kept sheep but they were named for their word for 'hammer'.

Silurian period covers the period 443 to 419 million years ago and named by Sir Roderick Impey Murchison, a friend of Adam Sedgwick, who named it after another Celtic tribe, the Silures. This Welsh tribe's name has most often been described as 'unknown', although this has not stopped a great number of suggestions. One suggests the personal name Essyllt giving the region the name Essyllwg and the people the Essyllwr. Essyllt was a daughter of the king of Germany and one of three damsels of celestial beauty, who married Locrinus and their daughter, Hafren, gave a name to the river Severn in which she drowned along with her mother.

Devonian period of 419 to 358 million years ago takes its name from Devon, again because this was where rocks from the period were first studied. The county is also named from a tribe iof Britons, the Dumnonii, who took their name from the Celtic dubnos and speaks of them as 'dwellers of the deep valley'.

Carboniferous, the period from 358 to 298 million years ago, is named because these rocks are said to be 'coal-bearing', coming from the Latin carbo 'coal' and fero 'I carry'.

Permian, 298 to 252 million years ago, was named in 1841 by Sir Roderick Murchison as these rocks were associated with the region of Perm Krai in Russia. Perm comes either from Finnish or Vepsian Peramaa or Hungarian perem meaning 'far away land' or 'edge' respectively.

Triassic period lasted from 252 to 201 million years ago. Named in 1834 by Friedrich von Alberti after three rock layers known as trias.

Jurassic lasted from 201 to 145 million years ago and is named from the Jura mountains, again where these rocks were first studied. The name Jura is from juria, a Celtic term for 'forest'.

Cretaceous, 145 to 65 million years ago, is a period named by Belgian geologist Jean d'Halloy in 1822 for the chalk beds found around the Paris Basin. The Latin creta means 'chalk'.

Eocene, from 65 to 33 million years ago, is named from the Ancient Greek eos 'dawn' and refers to the new fauna which appeared after the mass extinction of 65 million years ago.

Oligocene, 33 to 23 million years ago, is another from Ancient Greek, this time where oligos 'few' and kainos 'new' refers to the scarcity of molluscs found with the rock strat from this period.

Miocene period, 23 to 5 million years ago, is another from Greek, where meion 'less' and kainos 'new' means literally 'less recent' because this period has fewer marine invertebrates than the following.

Pliocene, from 5 million to 2.5 million years ago, was named by Sir Charles Lyell and, once again, comes from the Greek. Here pleion 'more' and kainos 'new' was chosen to mean 'continuation of the recent', a reference to the fossil molluscs found within these rocks which are essentially the same as seen today.

Pleistocene, from 2.5 million to just 11,700 years ago, comes from the Greek pleistos 'mostly' and kainos 'new', and shows this is almost as recent as the ages get.

Holocene has only been around sinc 11,700 years ago and means 'entirely recent' from the Greek holos kainos.

These time spans are further divided into periods, epochs, and ages and all with much more imaginative names than simply 2017. Happy New Year.