Page:South African Geology - Schwarz - 1912.djvu/14

10 nature which are probably erroneous, and have to be altered continually as new facts come to light so that Geology lacks the definiteness of the other sciences, in which the subject-raster can be put into bottles, and is a halfway house to those abstract sciences like Ethics, Psychology and so forth, where the subject-matter consists of images and ideas which have no concrete existence. On the other hand, the subject-matter is so vast that anyone who takes up the work seriously is presented with a field of observation and research that can never be exhausted, and even one who has but a casual knowledge of the science can find subjects of unending interest in any and every locality in the wide world.

Theories about the origin of the earth, the mountains, the valleys, the seas, and the lakes have been formulated from time immemorial, but the modern science dates from the teaching; of two men — Werner and Hutton. Abraham Gottlieb Werner was appointed professor of mineralogy at the Freiberg School of Mines in Saxony, in 1775; he rapidly became famous, and men from all parts of the world assembled in his classroom to hear him lecture on Geology. His principal thesis was that all rocks had been deposited from water, and that even the crystalline rocks had so originated when the sea was practically a chemical solution in the beginning. Hutton, however, who was by profession a doctor of medicine in Edinburgh, found that the crystalline rocks had been intruded in a molten state into the aqueous or sedimentary rocks, and in 1788 he published his Theory of the Earth, in which he set forth his views. Werner's theories were described as those of the Neptunian school, as the central idea was aqueous deposition; Button's theories, on the other hand, were called those of the Plutonian school,