Most of Earth’s salt is dissolved in the oceans. But there is also a significant amount of solid salt among continental rocks. And because of their mechanical properties, salt formations can have a dramatic effect on the structure and evolution of the rocks that surround them. This gives rise to what we call salt tectonics – at first sight, a rather surprising juxtaposition of a soft, powdery substance with a word that connotes the larger scale structure of the crust.

In the podcast, Mike Hudec explains the origin of salt in the Earth’s crust and describes the structures it forms when subjected to stresses. He also discusses how salt can play in important role in the formation of oil and gas reservoirs.

Hudec is a research professor at the Bureau of Economic Geology at the University of Texas at Austin.

Megafloods are cataclysmic floods that are qualitatively different from weather-related floods. In the podcast, Vic Baker explains our ideas as to what causes megafloods and describes the striking evidence for such floods in the Channeled Scablands of Washington State and in the Mediterranean.Vic Baker has been studying megafloods for over 50 years. He is a Professor of Hydrology and Atmospheric Sciences, Geosciences, and Planetary Sciences at the University of Arizona.

The planets formed out of a cloud of gas and dust around the nascent Sun. Within the so-called snow line, it was too hot for liquid water to exist. Since the Earth lies well within this line, why does it have water? Did it somehow manage to retain water from the outset or did it acquire its water later? In the podcast, Lindy Elkins-Tanton explains how these two scenarios might have played out but she says the evidence strongly favors one of these theories.

Elkins-Tanton has concentrated much of her research career on the formation and evolution of planets, and especially the role of water. She is a Professor in the School of Earth and Space Exploration at Arizona State University and Principal Investigator of the NASA Psyche mission.