Evidence for Catastrophes in The Evolution of Earth and Life

 

Nineteenth Annual Darwin College Lecture Series 2004

Lecture 6   :   February 20th 2004

Vincent Courtillot

Institut de Physique du Globe and University Paris

 

Abstract

The title of this lecture contains (almost) only four words, each of which could be a topic for a Darwin College series. With Darwin and Lyell (respectively), we have learnt that both Life (studied by Biology) and Earth (studied by geology) had mostly evolved slowly, at a rather continuous pace, over the immense depth of geological time. This world view has come to be known as "uniformitarianism", the main line of thought in these sciences to this day (and a very successful one in many respects). Cuvier's 18th century views of catastrophic episodes was all but obliterated. But, maybe in relation with a rather agitated social and political life, "catastrophism" has been resurrected in a modernized way in the last quarter of the 20th century. We shall review some of the Evidence for mass extinctions of Life, and eruption of gigantic lava flows (traps) at a few (geologically short) times of fast change. We shall discuss recent evidence that the dates of these events seem to often coincide. This may lead us to discuss the meaning of "Evidence" in such scientific endeavours. And to conclude that both Earth and Life (which are intimately related) most often proceeded smoothly as envisioned by Darwin ("survival of the fittest") and Lyell, but that a few brief catastrophes from time to time completely reoriented the course of biological and geological history: these were times of "survival of the luckiest". When is the next such event due? And shall we be lucky?

Biography

Vincent Courtillot is a professor of geophysics at Institut de Physique du Globe and University Paris 7 (Denis-Diderot), and has taught at Stanford, UC Santa Barbara and Caltech. He holds degrees from the Paris School of Mines, Stanford University, University of Paris 6 (Pierre et Marie Curie) and University of Paris 7 (Denis-Diderot). His research has focused on the Earth's magnetic field, both past and present (geomagnetism and paleomagnetism) and on plate tectonics and Earth geodynamics, about which he has published over 150 papers. In 1999, he published a book entitled Catastrophes in Earth's History : the science of mass extinction (Cambridge University Press). Vincent Courtillot is a Fellow of the American Geophysical Union and of the Royal Astronomical Society and a member of Academia Europaea and the French Academy of Sciences. He has received a number of awards from CNRS (Silver Medal) and the French Academy of Sciences (Gay and Dolomieu prizes). He is past president of the European Union of Geosciences and has been in charge of overseeing French research organizations, research funding and graduate studies in French universities, in various capacities as director or special advisor of the Ministries in charge of Education, Research and Technology (in 1988-93 and 1997-2001). He currently chairs the scientific council of the City of Paris. 

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