Geology Bites: An Earth and Planetary Science Podcast

Gillian Foulger is a leading proponent of the plate hypothesis of volcanism, which posits that volcanism away from plate boundaries can be explained by extensional deformation of the lithosphere with melting of the upper mantle.  The plate hypothesis uses plate tectonic theory to explain all volcanism without invoking plumes or hot-spots that originate in the lower mantle.  She hosts a lively debate on whether mantle plumes exist at mantleplumes.org.

Gillian Foulger is Emerita Professor of Geophysics at Durham University.  A key prediction of the plate hypothesis is that the lithosphere should be extending wherever we see intra-plate volcanism.  She explains that many of the observations we already have can be reinterpreted as consistent with the plate hypothesis, and suggests new experiments that could clearly distinguish the competing hypotheses.

For podcast illustrations go to geologybites.com.

Sarah Stewart uses computer-based dynamical simulations and lab experiments to create scenarios for the collision of a massive body with the Earth that can reproduce the composition, orbits, and spins of the Earth and Moon today.  

Sarah Stewart is a Professor in the Department of Earth and Planetary Sciences at the University of California Davis.  In the podcast, she explains how, following a massive impact with another body, the Earth formed a synestia - an inflated disk of gas in which the impacting body and Earth were thoroughly mixed, and out of which the Moon and a new Earth solidified.

For podcast illustrations, including videos of simulated Moon-forming impacts with synestias, and orbital simulations, go to geologybites.com.

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.