August 29, 1902.] 



SCIENCE. 



32a 



I have often defined geology as the applica- 

 tion of the principles of astronomy and 

 physics and chemistry and mineralogy 

 and biology to the earth. 



Certainly the earth is the single enormous 

 complex aggregate of matter directly with- 

 in the reach of man. This highly compos- 

 ite earth is the joint result of the work of 

 astronomical, physical, chemical and bio- 

 logical forces ; working on an incomparably 

 vaster scale than can ever be imitated in our 

 laboratories. A study of these mighty 

 results has already advanced at many 

 points astronomy, physics, chemistry and 

 biology, and future studies made with 

 direct reference to the causes which have 

 produced the earth are sure to lead to even 

 greater advances in these studies. 



If geology is to become a genetic science, 

 or, more simply, is to become a science under 

 the laws of energy, geology in large meas- 

 ure must become a quantitative science. 

 In the past it has been too frequently true 

 that because a single force or agent work- 

 ing in a certain direction is a real cause 

 of a phenomenon, the conclusion is drawn 

 that it is a sufficient cause. Only occasion- 

 ally has the question been asked, 'Is this 

 cause only a real cause, but is it an adequate 

 cause?'. Very -often differences of opinion 

 have arisen between geologists, one holding 

 that this cause is the one which explains 

 the phenomenon; another holding that 

 that is the explanation, and each insisting 

 that the other is wrong. In such cases very 

 rarely is the question asked whether the 

 explanations offered are contradictory or 

 complementary. In many cases the expla- 

 nation is not to be found in one cause, but 

 in several or many, and thus frequently the 

 conclusions which have been interpreted to 

 be contradictory are really supplementary. 

 To illustrate: But few writers have as- 

 signed more than, a single cause for crustal 

 shortening. One has held that secular cool- 

 ing is the cause; another has given a dif- 



ferent one, and has held that secular cooling 

 is of little consequence. But it is certain 

 that secular cooling, vuleanism, change of" 

 oblateness of the earth, change of pressure 

 within the earth, changes of form of the 

 material of the earth, and various other 

 causes, are not exclusive of one another, 

 but are all supplementary. The ability to 

 perceive the supplementary nature of vari- 

 ous explanations offered for a phenomenon 

 is one of the most marked, perhaps the 

 most marked, characteristics of the superior 

 man. The new geology must not only 

 ascertain all of the real causes for crustal 

 shortening, and other phenomena, but in 

 order satisfactorily to solve the problems 

 it must determine the quantitative impor- 

 tance of each. Geology within the next few 

 years is certain to largely pass to a quan- 

 titative basis. 



If I have correctly stated the relations 

 of geology to the other sciences, it follows 

 as a corollary that those only can greatly 

 advance the principles of geology who have 

 a working knowledge of two or more of 

 the sciences upon which it is based. 



By a working knowledge of a science I 

 mean such a knowledge of its principles as 

 makes them living truths. One must not 

 only be able to comprehend the principles, 

 but he must see them in relation to one 

 another; must be able to apply them. It 

 is not sufficient for a carpenter to be able 

 to explain how the hammer and saw and 

 plane and chisel work; he must be able 

 to use them. He must be able to hit the 

 nail on the head; to cut straight; to 

 plane smooth; to chisel true; and do all 

 upon the same piece of timber so as to 

 adapt it to a definite purpose in a building. 

 Just so the geologist must be able to apply 

 as tools the various principles of physics 

 and chemistry and biology and mineralogy 

 to the piece of geology upon which he is 

 engaged; and thus shape his piece to its 

 place in the great structure of geological 



