Most rocks were formed many millions of years ago.  Since then, some have been largely left alone, while others have been baked at high temperatures and buried at great depths.  Clare Warren explains how we can now uncover remarkably precise histories of such rocks, even if they have been through more than one episode of such extreme treatment.

Clare Warren is a Senior Lecturer in the School of Environment, Earth and Ecosystem Sciences at The Open University.

For more on Geology Bites, go to geologybites.com, where you can also find diagrams and pictures that support the podcast.

Why do some volcanoes erupt almost all the time but others lie dormant for centuries, millennia, or even longer?  Steve Sparks has turned our ideas about volcanoes upside down.  Not quite literally, but by applying the physics of fluid motion to the rocks and magma below volcanoes, he discovered that magma forms at much greater depths than previously thought, eventually forming an unstable blob that forces its way up through as much as a hundred kilometres of overlying rocks to erupt from a volcano.  It is how quickly such blobs form that determines how frequently a volcano will erupt. 

For more on Geology Bites, go to geologybites.com, where you can also find diagrams and pictures that support the podcast.

Steve Sparks has turned our ideas about volcanoes upside down.  Not quite literally, but by applying the physics of fluid motion to the rocks and magma below volcanoes, he discovered that magma forms slowly at much greater depths than previously thought, eventually forming an unstable blob that forces its way up through the overlying rocks to erupt from a volcano. 

Why look to another planet to reveal something new about the Earth?  Dan McKenzie describes an ingenious way of using the data sent back from the Magellan Venus orbiter to discover that Venus is covered with an elastic plate about 30 kilometers thick.   Explaining this very unexpected result revealed something extraordinary about the Earth.

For more on Geology Bites, go to geologybites.com, where you can also find diagrams and pictures that support the podcast.

In this episode, James Jackson explains what happens, geologically-speaking, during an earthquake, why they strike where they do, and why earthquake-prone places are such attractive places to live.

For more on Geology Bites, go to geologybites.com, where you can also find diagrams and pictures that support the podcast.

Mike Searle applies the theory of plate tectonics to explain what causes mountains of all kinds to form.  They range from enormous mountain belts such as those that stretch from the Himalaya to the Alps, to mid-ocean volcanoes such as Hawaii.

Mike Searle is Professor of Earth Sciences at Oxford University.  For over 30 years he has been studying the Himalaya, Karakoram, and the Tibetan Plateau.  He has summarized his work in a richly illustrated book entitled Colliding Continents. 

For illustrations that support the podcast go to geologybites.com.