Geology Bites

Dietmar Müller and his team have built interactive software to combine hundreds of diverse geological research studies into a single self-consistent picture of the plate-tectonic motions over deep time.  He explains how this astonishing feat was accomplished and points out salient features in the results.

Dietmar Müller is Professor of Geophysics at the University of Sydney.   In February 2021, his team published an animated billion-year plate reconstruction, which has had an enormous impact on the public.

Watch A Billion Years of Earth History in 40 Seconds

Go to geologybites.com for podcast illustrations and to learn more about Geology Bites.

Bob Anderson is chair of the department of Geological Sciences at the University of Colorado Boulder.  He is a geomorphologist who has studied many diverse aspects of the landscape, focusing recently on Alpine and Arctic landscapes in which ice plays a prominent role.  It was his sense of awe and aesthetic appreciation of patterns in nature that drew him into the field.

In the podcast he uses the Sierras as a classic example of how the nature of the bedrock shapes landscape, and explains how the use of cosmogenic radionuclides has revolutionized our ability to uncover the timing of the processes shaping the Earth’s surface.

Bob Anderson is also an accomplished photographer.  Go to geologybites.com to see some of his pictures as well as other images that illustrate the material he talks about. 

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. He is a true puzzle-master, piecing together all the available clues, especially those locked up in the magnetic fields imprinted into rocks when they formed, to trace the formation and subsequent break-up of supercontinents.

To see podcast illustrations and learn more about Geology Bites, go to geologybites.com.

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 collections come about? And what sort of things does the National Geological Repository hold?

Mike Howe is Head of the National Geological Repository. Under his leadership, the British Geological Survey has become a world leader in promoting public access to the collection through digitization and web delivery.  Perhaps most remarkably, 3D digital models have been made from 3D scans of over two thousand of the type fossils in the repository.

For podcast illustrations, links to the Repository's collections, and to learn more about Geology Bites, go to geologybites.com.

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 of northern Canada looking for emeralds.

Go to geologybites.com for images of the gemstones discussed in the podcast and to learn more about Geology Bites.

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, albeit at very low resolution, of the entire mantle.  The images surprised us by revealing some dramatic features in the lower mantle.

Allen McNamara is a Professor of Geological Sciences at Michigan State University.  He uses computer-based fluid mechanical models to investigate the behavior of the mantle, working in tandem with the seismologists to understand the origin and dynamics of these recently discovered features in the mantle.

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 Phobos?  What might we learn from such a mission?

Tomo Usui is a professor in the Department of Solar System Sciences at the Institute of Space and Astronautical Science of the Japan Aerospace Exploration Agency.  He is leading the science team for the mission to Phobos.

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 and diversify so vigorously in the early Cambrian?

Rachel Wood is Professor of Carbonate Geoscience at the University of Edinburgh. She and her team have uncovered fossils that suggest that the fuse of the so called Cambrian explosion was lit in the Ediacaran – the geological period that preceded the Cambrian.

Go to geologybites.com for illustrations that include pictures of the Ediacaran fossils Rachel Wood discusses in the podcast and of some of the locations in Siberia and Namibia where she found them, as well as to learn more about Geology Bites.

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 a Professor of Geosciences at the University of California, Los Angeles.  

Go to geologybites.com to see podcast illustrations and to learn about other Geology Bites episodes. 

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 Scripps Institution of Oceanography. 

Go to geologybites.com to see an animation of the global magnetic field patterns around the time of the last major excursion about 40,000 years ago when the Earth's magnetic field almost vanished entirely. 

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 discovering about the planet’s past evolution.

Go to geologybites.com for illustrations relating to this podcast and to learn more about Geology Bites.

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 will resolve, as well as a type of volcanism occurring on some icy bodies in the outer solar system called cryovolcanism.

Go to geologybites.com for illustrations supporting this podcast and to learn more about Geology Bites. 

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 the origin of the very oldest planetary materials from which the Earth was made.  Asteroids are a good place to look for such materials, and, to that end, he is Mission Sample Scientist for OSIRIS-REx, a NASA asteroid sample return mission, as well as a member of the Japanese asteroid sample return mission called Hayabusa 2.  He explains how the sample was captured, and what we hope to learn from analyzing it back on Earth.

Go to geologybites.com for illustrations relating to the podcast and to learn more about Geology Bites.

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 the Mediterranean.

Visit geologybites.com to see maps and animations of the Mediterranean's geological history and of the processes discussed in the podcast. 

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 demands a transformation of our energy strategy, he became a prominent voice for change in the oil industry.   Here, he discusses how he sees this change coming about. 

Go to geologybites.com for illustrations that support this podcast, as well as to learn about other Geology Bites episodes.

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 how his recent research has uncovered new evidence that may finally explain what caused the end-Devonian mass extinction.

Go to geologybites.com for illustrations that support this podcast and to learn more about the series.

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 at the Department of Earth Sciences at Oxford University.   By analyzing the relationship between mineral deposits, principally in Africa and Asia, and our latest understanding of plate tectonics and mountain-building, he has unraveled the processes that formed some of our most important mineral deposits.

Go to geologybites.com for illustrations that support this episode as well as to learn more about the podcast series.

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 Bites podcast series.

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 Professor at Scripps Institution of Oceanography at the University of California San Diego.

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 Paris.

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 professor of planetary sciences and leader of the Planetary Materials Group at the Natural History Museum in London.  Her research seeks to unravel how the solar system formed and cast light on questions such as how the Earth got its water and organic materials.  She even has an asteroid named after her.

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.

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.