Category Archives: metamorphism

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 … Continue reading

Categories: Ireland, metamorphism, tectonics

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 … Continue reading

Categories: Ireland, metamorphism, mountains, subduction, tectonics

How to make a rock from scratch

“If you wish to make an apple pie from scratch, you must first invent the universe.” Carl Sagan. I have a handsome piece of rock in my hand. How did it come to be, how was it made? A perfectly … Continue reading

Categories: geochemistry, metamorphism, subduction

Eclogites: back to the surface

Eclogites are beautiful rocks that form deep within subduction zones. The vast majority of subducted oceanic crust becomes more dense than the surrounding mantle rocks and travels to the strange world of the deep earth. Lucky for us, small volumes … Continue reading

Categories: eclogites, metamorphism, subduction, tectonics