Page:Popular Science Monthly Volume 31.djvu/223

Rh necessary dogma of uniformitarianism. It is extremely astonishing to me that any one who has carefully studied Lyell's great work can have so completely failed to appreciate its purport, which yet is "writ large" on the very title-page: "The Principles of Geology, being an Attempt to explain the Former Changes of the Earth's Surface by Reference to Causes now in Operation." The essence of Lyell's doctrine is here written so that those who run may read; and it has nothing to do with the quickness or slowness of the past changes of the earth's surface, except in so far as existing analogous changes may go on slowly, and therefore create a presumption in favor of the slowness of past changes.

With that epigrammatic force which characterizes his style, Buff on wrote, nearly a hundred and fifty years ago, in his famous "Théorie de la Terre," "Pour juger de ce qui est arrivé, et même de ce qui arrivera, nous n'avons qu'à examiner ce qui arrive." The key of the past, as of the future, is to be sought in the present, and only when known causes of change have been shown to be insufficient have we any right to have recourse to unknown causes. Geology is as much an historical science as archaeology; and I apprehend that all sound historical investigation rests upon this axiom. It underlay all Hutton's work, and animated Lyell and Scrope in their successful efforts to revolutionize the geology of half a century ago.

There is no antagonism whatever, and there never was, between the belief in the views which had their chief and unwearied advocate in Lyell and the belief in the occurrence of catastrophes. The first edition of Lyell's "Principles," published in 1830, lies before me, and a large part of the first volume is occupied by an account of volcanic, seismic, and diluvial catastrophes which have occurred within the historical period. Moreover, the author over and over again expressly draws the attention of his readers to the consistency of catastrophes with his doctrine:

Notwithstanding, therefore, that we have not witnessed within the last three thousand years the devastation by deluge of a large continent, yet, as we may predict the future occurrence of such catastrophes, we are authorized to regard them as part of the present order of Nature, and they may he introduced into geological speculations respecting the past, provided that we do not imagine them to have been more frequent or general than we expect them to be in time to come (vol. i, p. 89).

Again:

If we regard each of the causes separately, which we know to be at present the most instrumental in remodeling the state of the surface, we shall find that we must expect each to be in action for thousands of years, without producing any extensive alterations in the habitable surface, and then to give rise, during a very brief period, to important revolutions (vol. ii, p. 161).