Oceanic plates are continually manufactured at mid-ocean spreading ridges.  But exactly what processes go on at these ridges?  It turns out that it depends on what type of ridge it is - fast-spreading or slow-spreading.  And that our traditional view of vanishingly thin plate thickness at ridge axes is inaccurate.  Mathilde Cannat describes our modern understanding of mid-ocean ridges and the observations that led us there. Mathilde Cannat is a research director at the Institut de Physique du Globe of Paris. Her research on mid-ocean ridges has fundamentally changed our understanding of the geological processes that create new oceanic crust at these ridges. For podcast illustrations and more about Geology Bites, go to geologybites.com.