250 Million Years Ago
An 300 Milliún Bliain Seo Caite – I nDiaidh na Tréimhse Carbónmhaire
Níl aon taifid chloiche inár réigiún geopháirce le haghaidh an 250 milliún bliain ina dhiaidh sin. Tá a fhios againn ó cheantair eile in Éirinn gur lean an mhórchríoch ag bogadh ó thuaidh, i ndiaidh mórchríoch eile ar a taobh ó dheas a bhuaileadh, a spreag roinnt dífhoirmiúcháin ar an mbuncharraig agus ardú fhormhór mhórchríoch na hÉireann go leibhéal ní b’airde ná leibhéal na farraige mar a bhí ag an am sin. Toisc gur gnách le formhór na dríodar luí agus bailiú in imchuacha, amhail grinneall na farraige, chiallaigh ardú mhórchríoch na hÉireann os cionn leibhéal na farraige gur bheag dríodar a sil-leagadh in Éirinn le linn an 250 milliún bliain seo.
Ó thaobh na teicteonaice de, ba é an chéad mhórimeacht eile a taifeadaíodh sa réigiún geopháirce oscailt an Aigéin Atlantaigh thart ar 65 milliún bliain ó shin, ag deireadh na Tréimhse Cailcí agus tús na Tréimhse Pailéigéiní. Cuireadh tús leis seo le tanú na screimhe ilchríochaí agus oscailt scoilteanna ina dhiaidh sin.
Cracks in the bedrock were formed and were “plugged” by limited intrusions of magma in our geopark area, as seen by the dolerite sill on top of the Partry mountains at Droimchogaidh. This rifting activity that separated Ireland from Greenland and North America is also now thought to be responsible for the formation of the mountains that we see today in the west of Ireland. A section of Carboniferous sandstone that predates the Carboniferous limestone of Ireland is found on top of the Maumtrasna plateau, which sits 400m above the sea level. The same sandstoneis also found at a depth of 300m below the surface around Clonbur. This indicates that the rocks west of Lough Mask and Lough Corrib were uplifted by about 700m. This would have occurred when the early spread of oceanic crust pushed the two landmasses apart, which would have locally pinned blocks of bedrock against one another in a limited space and pushed them upwards.