Cork City’s Geological History Before we shift the focus to Cork City’s geological sites and heritage, it is fitting that we get an overview of its geological history. Here, ‘geological history’ means whatever we know about the prehistoric location, atmosphere, life forms, landscape and other properties of an area as it has changed over millions of years. You may have heard about the Devonian, Carboniferous and Quaternary periods. If you haven’t, let’s do a crash course.
Geological Timeline of Cork
Except these!
Most dinosaurs go extinct Mammals take over
Caledonian Orogeny
Cork is a huge arid floodplain
Cork is a tropical sea
Variscan Orogeny
Mass extinction Age of the reptiles begins
Cork during the Ice Age
Erosion
Marine sedimentary rocks
Old Red Sandstone
Dry and warm climate
Paleogene and neogene periods
Today
Jurassic period
Devonian period
Carboniferous period
Permian period
Cretaceous period
Triassic period
Age of humans
-420 million years
-360 million years
-300 million years
-250 million years
-65 million years
Silurian period
4.5 billion years: Earth forms 13.8 billion years: The universe forms
Our planet is staggeringly old having formed around 4.54 billion years ago. So, as a way of categorising and dividing this ridiculously long stretch of time, geoscientists set up what is today the International Geological Time Scale. Just as historians have set up periods in Irish (human) history such as Gaelic, Viking and Medieval Ireland, geoscientists have terms such as Devonian, Carboniferous, Jurassic and Quaternary to describe incredibly long periods of time in Earth’s history. The first evidence we have of Cork’s past appears 380 million years ago during the late part of the Devonian Period. This is the Old Red Sandstone that you will read and see more about in the coming chapters. The rocks of Cork are from the geological time periods Devonian, Carboniferous and Quaternary. Overall, it looks something like this - listed from oldest to youngest:
n Devonian Old Red Sandstone. n Carboniferous sandstones, siltstones and mudstones. n Carboniferous limestone. n Quaternary glacial sediments
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