Geology Bites

Many of us have heard about the most recent supercontinent, which is called Pangea. But there is strong evidence for others with the earliest one now speculated to have formed in the Neoarchaean era about 2.7 billion years ago. So what makes us think they existed? And if they are real, how did they form and then break up? David Evans is Professor of Earth and Planetary Sciences at Yale University....

Many countries have national geological museums that house collections of rocks, minerals, and fossils. But the UK has two collections – the one at the Geological Museum in London, and, in addition, the National Geological Repository located near Nottingham, which is part of the British Geological Survey, and which is actually very much the larger of the two collections. How did the two collection...

Gemstones have value not only because they are beautiful, but also because there are rare.  So what exactly is a gemstone, and what make them so rare?  Lee Groat is a Professor in the Department of Earth, Ocean, and Atmospheric Sciences at the University of British Columbia.   He studies the mineralogy of gemstones and also works in the field, having conducted surveys of parts...

The lower reaches of the Earth’s mantle extend all the way down to the boundary with the metallic core, which lies about 2,900 kilometers below the surface.  We knew almost nothing about this highly inaccessible region until good seismic measurements became available in the 1970s.  That coincided with a rapid increase in computer power, which enabled seismologists to generate images, alb...

The rocky planets of the solar system have only three moons among them: our own Moon, and the two much smaller moons of Mars – Phobos and Deimos. There have been no successful missions to either of the Martian moons, but now the Japan Aerospace Exploration Agency is sending a probe to Phobos to be launched in 2024, to land and collect material from its surface, and return it to Earth. But why Phob...

The Eon in which we live is called the Phanerozoic, which comes from the ancient Greek word for visible life. The eon starts with the Cambrian, which began 541 million years ago. But in recent decades it has become increasingly clear from the fossil record that there was visible life before the Cambrian, and complex life at that. So what caused it to emerge then, and what caused it to proliferate...

Carolina Lithgow-Bertelloni views plate tectonics and the Earth's topography as an expression of the interior processes of the Earth, and in particular of the horizontal and vertical motions of the mantle.   Here she explains why we think that up to a full kilometer of the Earth's topography is caused by the mantle's direct push or pull on the lithosphere. Carolina Lithgow-Bertelloni is...

Cathy Constable reconstructs global maps of the Earth’s magnetic field over timescales from millennia to millions of years using the remnant magnetism “frozen” into human artifacts and rocks.  This has revealed surprising patterns of variation that in turn cast light on the processes in the Earth’s core that are responsible for generating the field. Cathy Constable is a Professor at the Scrip...

Bärbel Hönisch uses the skeletal remains of foraminifera as her raw material in reconstructing ocean and atmospheric conditions that prevailed in past geological periods.  Trace chemical constituents in these creatures can record the temperature of the ocean and carbon dioxide of the atmosphere.  Climate models being applied to the present day are being validated by what she is discoveri...

David Rothery investigates volcanism on Earth and elsewhere in the Solar System using remote-sensing Earth-orbiting satellites and space probes.  Mercury is his present focus, and he is lead co-investigator for geology on the X-ray spectrometer aboard BepiColombo, an ESA mission currently on its way to Mercury.  He describes some intriguing puzzles about Mercury that he hopes BepiColombo...

There are some things we just cannot learn about other bodies in the solar system without actually having our hands on a sample of the body and analyzing it on Earth using the battery of techniques that have been refined for the analysis of terrestrial rocks.  Harold C. Connolly Jr. is Professor and Founding Chair at the Department of Geology at Rowan University.  He investigates th...

Laurent Jolivet is an expert on the dynamics of tectonic plates and the mantle and is a Professor at the Institute of Earth Sciences at the Sorbonne University.  He combines satellite measurements, seismic tomography, field observations, and computer modeling to reconstruct plate motions, even in some of the most complicated parts of the world.  Here he unravels the tangled evolution of...

Sir Mark Moody-Stuart is a former chairman of Royal Dutch Shell and is a director of Saudi Aramco, which has the largest daily oil production of any oil-producing company.  He obtained a PhD on the Devonian sediments of Spitsbergen before joining Shell, where he started his career as a geologist in Spain, Oman, Brunei, and Australia. After recognizing that our response to global warming deman...

The Earth has endured many mass extinctions.  We are pretty confident that we know what caused these events.  Except for one of them: the one at the end of the Devonian period 360 million years ago.  John Marshall is a fossil expert specializing in mass extinction events and is a Professor at the School of Ocean & Earth Science at the University of Southampton.  He explains...

So much of what we make starts with materials we extract from the Earth.   Some of these materials make up only a tiny proportion of our planet, but fortunately for us, they are concentrated in certain places, which makes it possible to extract them in economically viable quantities.   So how exactly do these materials become concentrated? Lawrence Robb is a Visiting Professor...

Bruce Buffett is a Professor in the Department of Earth and Planetary Science at the University of California, Berkeley.   He investigates the structure and motions within the Earth’s core by matching physics-based simulations of the core to the observed magnetic field of the Earth. Go to geologybites.com for diagrams that support this podcast episode as well as more about the Geology Bi...

David Sandwell uses satellites to make accurate measurements of the shape of the ocean surface.  He explains how this enabled him to create a global map of the topography on the sea-floor.  This revealed the global extent of classic plate-tectonic features, such as spreading ridges and transform faults, but also intriguing new features we still do not understand. David Sandwell is a Prof...

Barbara Romanowicz uses the seismic waves triggered by earthquakes to probe the interior of the Earth.  She has forged new techniques for analyzing these waves to give us a much sharper view of the deep structure of the Earth.  She is a Professor of the Graduate School at the University of California at Berkeley, and Chair of Physics of the Earth’s Interior at the Collège de France in Pa...

The Earth was formed just over 4.5 billion years ago.  What happened just after it formed and what were conditions like then?  John Valley reveals what we have managed to discover about our planet’s very distant past, and how we did it.

The asteroid belt lies between the orbits of Mars and Jupiter.   It formed out of the same protoplanetary disc as the Earth, but many asteroids have barely changed since then.  Sara Russell explains what these time capsules can reveal about the Earth and how we will learn much more from the spacecraft currently fetching and returning asteroid samples to Earth. Sara Russell is a prof...

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 Sc...

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 unstab...

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 geologybi...

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 P...