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Catastrophism

Cuvier came to believe that most, if not all, the animal fossils he examined were remains of species that had become extinct. Near the end of his 1796 paper on living and fossil elephants, he said:

Contrary to many natural scientists' beliefs at the time, Cuvier believed that animal extinction was not a product of anthropogenic causes. Instead, he proposed that humans were around long enough to indirectly maintain the fossilized records of ancient Earth. He also attempted to verify the water catastrophe by analyzing records of various cultural backgrounds. Though he found many accounts of the water catastrophe unclear, he did believe that such an event occurred at the brink of human history nonetheless.

This led Cuvier to become an active proponent of the geological school of thought called catastrophism, which maintained that many of the geological features of the earth and the history of life could be explained by catastrophic events that had caused the extinction of many species of animals. Over the course of his career, Cuvier came to believe there had not been a single catastrophe, but several, resulting in a succession of different faunas. He wrote about these ideas many times, in particular, he discussed them in great detail in the preliminary discourse (an introduction) to a collection of his papers, Recherches sur les ossements fossiles de quadrupèdes (Researches on quadruped fossil bones), on quadruped fossils published in 1812.

Cuvier's own explanation for such a catastrophic event is derived from two different sources, including those from Jean-André Deluc and Déodat de Dolomieu. The former proposed that the continents existing ten millennia ago collapsed, allowing the ocean floors to rise higher than the continental plates and become the continents that now exist today. The latter proposed that a massive tsunami hit the globe, leading to mass extinction. Whatever the case was, he believed that the deluge happened quite recently in human history. In fact, he believed that Earth's existence was limited and not as extended as many natural scientists, like Lamarck, believed it to be.

Much of the evidence he used to support his catastrophist theories has been taken from his fossil records. He strongly suggested that the fossils he found were evidence of the world's first reptiles, followed chronologically by mammals and humans. Cuvier didn't wish to delve much into the causation of all the extinction and introduction of new animal species but rather focused on the sequential aspects of animal history on Earth. In a way, his chronological dating of Earth's history somewhat reflected Lamarck's transformationist theories.

Cuvier also worked alongside Alexandre Brongniart in analyzing the Parisian rock cycle. Using stratigraphical methods, they were both able to extrapolate key information regarding Earth history from studying these rocks. These rocks contained remnants of molluscs, bones of mammals, and shells. From these findings, Cuvier and Brongniart concluded that many environmental changes occurred in quick catastrophes, though Earth itself was often placid for extended periods of time in between sudden disturbances.

The 'Preliminary Discourse' became very well known and, unauthorized translations were made into English, German, and Italian (and in the case of those in English, not entirely accurately). In 1826, Cuvier published a revised version under the name, Discours sur les révolutions de la surface du globe (Discourse on the upheavals of the surface of the globe).

After Cuvier's death, the catastrophic school of geological thought lost ground to uniformitarianism, as championed by Charles Lyell and others, which claimed that the geological features of the earth were best explained by currently observable forces, such as erosion and volcanism, acting gradually over an extended period of time. The increasing interest in the topic of mass extinction starting in the late twentieth century, however, has led to a resurgence of interest among historians of science and other scholars in this aspect of Cuvier's work.