BSW3A 4. Geology of the valley

Speaker: John McGroaryFrom The Bluestack Way - Part 3 playlist.The panorama looks north to the western part of the Bluestack mountains. The most westerly mountain is Binbane, the long ridge to the east is Cloghmeen Hill which passes into the more rugged peal of Carnawen. The windfarm at Meenaguse and the mountain to the east of this is Binnasruell. The rocks that form the mountains are 600 million years old and are made up of quartzites – sandstones that have been heated and compressed by the earth's forces and become even harder and more resistant to erosion.  All the low hills in the foreground are underlain by 325 million year old Carboniferous age Drumkeelan Sandstone. The low ground south of the Bluestack mountains is also underlain by 325 million year old shales, limestones and sandstones. The elevation of the ground also controls land usage e.g the lower and drumlin-covered ground has subsistence farms and irregular settlements. The area has also more modern land uses such as windfarms and commercial forestry while mountains are used for the rough grazing of sheep.  A major geological fault has brought older rocks of the mountains into contact with younger rocks of the foreground. The trace of this fault runs along the beak in slope of the mountains. The shape of the mountains is controlled by the rocks that form them. For example, Binbane has a gentler slope to the west, which becomes steeper towards the summit. This is due to different rocks one of which is more resistant to erosion than the other.  In our audio piece, John tells us how this area was once a tropical ocean