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Palaeoecology in West Cork

Ireland is a country that is well suited to palaeoecology.

In West Cork we have some lovely uplands, but we also have a lot of lowlands, and there are still a lot of small bogs and lakes. In a lot of cases the bogs and mires were too small to be commercially developed and so in most cases retain their sediments. They haven’t been dug for peat or turf.

In West Cork the geology is almost entirely siliceous, that is, made up from silica based rock, and so is potentially slightly acidic; as opposed to lime based rock, like limestone, containing lime (calcium carbonate), that would be alkali. Some rocks in West Cork have a slight calcareous element to them, but really there is only one small part of West Cork that has true limestone. An added complication with limestone is the effect that the carbonate can have on radiocarbon dating. Carbon from the limestone, released as the lime reacts with the slightly acidic rainwater, can alter the proportions of isotopes that are included by living organisms in their structure. In these cases the ratios of the different carbon isotopes do not reflect the atmospheric ratios, and although minute, this can affect the calculation and calibration of dates. But we do not have to worry about that here in West Cork.

Being a rural area the effects of past glacial action can still be quite easily seen. Indeed it can in most parts of Ireland, but again West Cork is special in that there was - it is thought - a separate ice sheet covering Cork and Kerry, which means a lot of the effects of glacial erosion and deposition are quite local. And also still quite fresh and visible.

(We need to be careful with the term glacial. It gives images of glaciers, rivers of ice moving ponderously down a valley. But a more realistic image should be of an ice sheet, a layer of ice maybe 200 or 300 or even 1000 metres thick, lying on top of, and moving across, the landscape, sometimes, but not always, following the topography. Also bear in mind that the sea level was quite a bit lower, 100m or more, so most of what we know as the coast now was five or even ten miles inland then.)

As mentioned in the introduction, palaeoecological analysis can also be employed on rocks, and this has been done for the sedimentary rocks that make up the foundation of West Cork. Geologists studying the area over the past 100 years have combined knowledge of similar rocks of similar ages at other locations, and the fossils they contain. The results do not seem to be widely known - and they should be.

The geological palaeoecology of West Cork is a fascinating subject, and deserving of a separate blog entry (see here).