Good building stones get reused. Sometimes the only traces of very old buildings are their stones, built into more modern ones. It’s the same with rocks and mountain belts. Stone that now forms parts of the Himalaya was once part of a now-vanished mountain range. The Himalaya were formed by the collision between the Indian… Continue reading The Himalaya: mountains made from mountains
Category: metamorphism
The South Mayo Trough: tiny grains record huge events
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
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