Buffon, Desmarest and the ordering of geological events in époques
Published:January 01, 2001
During the eighteenth century many naturalists and philosophers became persuaded of the great antiquity of the Earth, and of the promise that knowledge of the Earth’s past and development could be built up through investigations of natural terrestrial features. In common with most geological issues of the time, these opinions rose to prominence to a considerable degree in connection with the so-called Theories of the Earth. This paper discusses some interconnections between Theories of the Earth and the emerging enterprise of geological field investigation, as they related to efforts toward establishing relative ages of geological phenomena. It considers in particular the two rather different Theories of the Earth offered by Buffon in 1749 and 1778, respectively. While the earlier one (Théorie de la Terre) emphasized principles for extracting physical knowledge of the Earth’s configuration through empirical investigation, the latter theory (Époques de la Nature) drew attention to the project of organizing knowledge about the Earth around a directional sequence of periods. The central impulses of Buffon’s two conceptions of the Earth were combined in actualistic field investigations by geologists of the late eighteenth century, Nicolas Desmarest in particular, which contributed significantly to the establishment of methods for determining distinct stages or sequences of the Earth’s past.
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The Age of the Earth: From 4004 BC to AD 2002
The age of the Earth has long been a subject of great interest to scientists from many disciplines, particularly geologists, biologists, physicists and astronomers. This volume, The Age of the Earth: from 4004 BC to AD 2002, brings together contributors from these different subjects, along with historians, to produce a comprehensive review of how the Earth’s age has been perceived since ancient times. Touching on the works of eminent scholars from the seventeenth to nineteenth centuries, it describes how concepts of the Earth’s history changed as geology slowly separated itself from religious orthodoxy to emerge as a rigorous and self-contained science. Fossils soon became established as useful markers of relative age, while deductions made from geomorphological processes enabled the discussion of time in terms of years. By the end of the nineteenth century biologists and geologists were fiercely debating the issue with physicists who were unwilling to give them the time needed for evolution or uniformitarianism.
With the discovery of radioactivity, attempts to calculate the Earth’s age entered a new era, although these early pioneers in radiometric dating encountered many difficulties, both technical and intellectual, before the enormity of geological time was fully recognized. This effort affected both the theory and practice of geology. Geochronology was largely responsible for it maturing into a professional scientific discipline, as increasingly refined techniques measured not only the age of the rocks, but the rate of processes which now elucidate many aspects of the Earth’s evolution.
Even today the Earth’s chronology remains a contentious topic — particularly for those dating the oldest rocks — and it is implicated in debates surrounding our hominid ancestors, the origins and development of life, and the age of the universe.
The Age of the Earth: from 4004 bc to AD 2002 will be of particular interest to geologists, geochemists, and historians of science, as well as astronomers, archaeologists, biologists and the general reader with an interest in science.