In this episode, Jiří Žák describes the two main orogenies whose remnants figure prominently in central European geology: the Cadomian orogeny that lasted from the late Neoproterozoic to the early Cambrian (c. 700 Ma to c. 425 Ma) and the Variscan orogeny that occurred in the late Paleozoic (c. 380 Ma to 280 Ma). The Cadomian took place on the northern margins of Gondwana, only later to rift and travel north to form what was to become Europe. The Variscan was caused by the collision of Gondwana with Laurussia in the final stages of the assembly of the supercontinent Pangea. Both orogenies have been heavily eroded, and we see their imprint in the form of metamorphic rocks, volcanic rocks, granites, and deformation structures. These are scattered across Europe, from southern Britain to eastern Europe.

Žák has been studying the geology of central Europe for over 25 years using methods ranging from structural studies in the field to detrital zircon geochronology. He is a Professor in the Institute of Geology and Paleontology at Charles University in Prague.

Subduction zones can be very long-lived, persisting for tens of even hundreds of millions of years. During that time they rarely stay still, but instead retreat, advance, move laterally, or reverse direction. In the podcast, Claudio Faccenna discusses the processes that govern these movements. It turns out that they depend not only on the properties of the subducting slab, but also on the environment, including the proximity of other subduction zones.

Faccenna has been studying how convergent margins evolve for over 30 years, concentrating particularly on the Mediterranean region. He is Head of the lithospheric dynamics section at the Helmholtz Center for Geosciences at GFZ in Potsdam in Germany and also a Professor at the Department of Science at Roma Tre University.

In the podcast, Cees Van Staal tells us about the Paleozoic tectonic events that led to the formation of the Appalachians. The events are closely related to those involved in the Caledonian orogeny and the mountains it created in what is now Ireland, Scotland, east Greenland, and Norway, as discussed in the episode with Rob Strachan. However, the Appalachians that we see today are not the worn-down remnants of the Paleozoic mountains. Instead, they reflect much more a topography that was created during processes associated with rifting and magmatism that accompanied the opening of the Atlantic Ocean as well as the effects of the ice ages as recently as about 10,000 years ago.

Van Staal has been studying the Appalachians for over 35 years, focusing especially on the large-scale tectonics of their formation. He is Emeritus scientist at the Geological Survey of Canada and an Adjunct/Research Professor in the Department of Earth and Environmental Sciences at the University of Waterloo in Ontario.