Sedimentary basins have been described as ‘tape recorders’ that preserve evidence of past events. Some sedimentary basins contain ‘recordings’ of grand tectonic events – plate collisions and mountain building. The information is stored as subtle but compelling patterns in the type of sand grains. Combined with studies of linked metamorphic and igneous rocks, they allow us… Continue reading The South Mayo Trough: tiny grains record huge events
Category: Ireland
Telling stories about Irish Geology
I clearly remember the most important moment of my geological career. I was resting my back on a glacially-polished wall of gabbro, my feet in an Irish bog, talking to myself in the sunshine. As a young man with bushy hair and beard, tattered field gear, wellington boots and a battered rucksack held together by darning… Continue reading Telling stories about Irish Geology
Structural Geology by the Deformation numbers
Structural geologists seek to understand how rocks have changed shape, in order to better understand wider processes such as how mountains are formed. Sometimes they use a terminology called ‘Deformation-numbers’ which I will now explain via a series of pretty pictures. Structural geologists spend their day measuring the orientations of things. These can be planar… Continue reading Structural Geology by the Deformation numbers
The Grampian / Taconic orogeny in Ireland – when arcs attack
Ever since the plate tectonic paradigm-shift of the 1960s, geologists have strived to understand ancient rocks in terms of the movements of plates. The geology of north-western Ireland can be explained by what happened when a subduction zone ran out of oceanic crust back in the Ordovician. Let me take you back to before that… Continue reading The Grampian / Taconic orogeny in Ireland – when arcs attack