Speaker for Tuesday 2nd December 2014 - Rev. Graham Nevin
Talk by the Rev. Graham Nevin on 'Northern Ireland - the last 100 Million Years'
In the absence of both Club President and Vice President, Past President Graham Kane took the chair, and welcomed members and guest John Tan to the meeting. The President then introduced our speaker for the morning Rev. Graham Nevin, who then set too, telling us about 'Northern Ireland - The last 1000 Million Years’.
The Reverend Nevin (Graham) began his talk by saying that it was a little difficult to compress 1000 million years of geological history into 30 minutes or so, and he was concerned that we may all finish up knowing less about Northern Ireland than we did before the talk begun! The fear was 'groundless' (sorry about the pun - Web Ed) as the former University of Ulster lecturer got into simplified academic mode, giving us all a clear view of history - even if the 'time scales' involved needed some thinking about!
To illustrate the talk, Graham showed the members a geological map of the Northern half of Ireland, showing the 'surface' rock in different colours for its geological type. It all looked quite colourful and complicated, but the map could be fairly clearly divided into four distinct areas, these Graham used to structure in talk.
Starting with the 'Top left' quarter of the map (the greater Donegal area) we have an array of rainbow colours, generally referred to as 'Dalriadian Rocks' - named after the legendary Kingdom of Dalriada (what else, for this part of the world! - Web Ed). These differing types of rocks are mainly formed from heat and pressure. Although colourful, in general terms, they are of little commercial or practical use.
Taking the next section, 'Bottom Right' on the map (mainly the Co. Down area) in contrast, we see the blue / gray colouring of sandstone and granite, formed 100s of million years ago. This is very useful commercially and gets exported all over the world as it makes high quality, low wear road surfacing. There's also extra deposits of mineable lead around the Conligh area.
Taking the 'Lower Left' area (greater Sligo region) of the map, we see mainly a 'Carboniferous' rock formation. This area started out originally 100s of million years ago as a warm shallow sea. Rivers washed down mud, which gradually filled up the sea and vegetation started to grow. The rock formation is mainly limestone (good for concrete) but there is surprisingly little coal deposited there.
Around 200m years ago the sea levels began raise (NOT as speculated in our time, as being up to a metre). The northern hemisphere saw 100s of meters rise in the sea. This in turn broke up the huge 'Pangaea' continent and changing our part of the world massively. We can see a little of this with the 'White Rocks' abound the Portrush area as rock strata and volcanoes pushed upwards. The 'Pinkie' colour of the 'Top Left' quarter of the map (the greater Antrim and North Coast area) shows the turbulent and volcanic nature of our historical geological past.
Graham's talk was followed by an interesting Question and Answer session. Among the things we asked were: 'Is there any danger of earth quakes?' - Not really, but there are many very minor 'quakes' or earth tremors happening all the time, we just don't realise what they are. 'What is the cause of the different grain size of Igneous Rock and Basalt?' - That's complicated, and would take longer to explain than the whole talk. 'Why don't we get 'Slates' mined her like in Wales?' - The 'sandy' deposits in the rock strata just don't reach out so far from Wales to Ireland. 'With the mineral deposits, did we get Bauxite Mines?' Yes, these were still active in the 1940's but not so long after.
At the end of the talk a vote of thanks was proposed by Des Johnston, who congratulated Graham on managing to compress so much information into so few minutes and make it both interesting and enjoyable, as well educational. Many thanks were due for such a fascinating talk. The thanks were passed on by the Past President. The members showed their appreciation.
Mike Turner, Secretary
