Notable ntnong the Plutonic adherents were Hutton (1726-97), and Playfair, one of Hut ton's most ardent followers. They, however, gave most to geology in another field. The cataclysmic events of earth history are most striking and the majority of the earlier students of geology, including Werner, belonged to the school of catastrophism; that is, they placed most emphasis on those changes in earth his tory that were sudden or startling. Hutton and Playfair, on the other hand, while not the first to see the slow processes of geologic nature, were the first to give to these slow activities their just place in the science. The school they founded has been called the school of uniformitarianism and their ideas still dominate geology. Sir Charles Leyell (1797 1875) became the greatest exponent of this school.
Paleontology, the study of which was gain ing in interest continually, received added im petus from the work of Lamarck (1744-1829) and Cuvier (1769-1832). the former of whom antedated Darwin, though less definitely so, in ideas of evolution. The final impetus to paleontology came in the Darwinian theory which is now inseparably linked with all pa leontologic research. The first real application of paleontology to stratigraphic correlation was made by William Smith (1769-1839), who showed that it was possible to trace certain formations for long distances by means of the fossils they contained. This constituted the real beginning of stratigraphy as the science is now known. Following him Murchison and Sedgwick carried the idea much farther and succeeded by the use of fossils in working out the extremely complicated succession of older rocks in western England and Wales.
Erratic bowlders scattered over England, over most of northern Europe, and over a large part of northern United States and Canada, were the cause of much geologic speculation. It was variously conjectured that they were carried there by Noah's flood, by rivers now extinct and by icebergs floating in an ocean much more extensive than that now existing. Playfair first suggested that they might have been transported by glaciers, but it remained for J. L. R. Agassiz (1807-73), whose studies of Swiss glaciers.well fitted him for his task, to demonstrate glacial efficiency in the transportation of such bowlders. He is quite properly called the father of glaciology.
In this brief sketch of the development of the science, many important names have neces sarily been omitted. Attention should be called, however, to those institutions and societies now actively furthering the science. Practically all large universities have departments of geology engaged not only in teaching but in research as well. Most of the civilized nations of first rank and many provinces, states and colonies main tain geological surveys whose major work is directed to the economic aspects of the sub ject. Most notable among such organizations are those of the United States, Canada, Great Britain, Germany and France, though many others are doing effective work. In the United States all hut a few of the individual States maintain surveys. These organizations all publish the results of their work, usually for free distribution.