Training of a Geologist. — Van Hise. 153 
comparably vaster scale than can ever be imitated in our labora- 
tories. A study of these mighty results has already advanced 
at many points astrononi}-, ph}-sics, 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 sciences. 
If geology is to become a genetic science, or more simply, 
is to become a science under the laws of energy, geology in 
large measure must become a cjuantitative science. In the 
past it has been too frequently true that because a single force 
or agent working in a certain direction is a real cause of a 
the phenomenon ; another holding that this is the explanation^ 
cause. Only occasionally has the question been asked 'Is 
this cause not only a real cause, but is it an adequate cause?' 
Very often differences of opinion have arisen between geol- 
ogists, one holding that this cause is the one which explains 
the phenomenon, another holding that this 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 coniplcnicntary. In many cases the ex- 
planation is not to be found in one cause, but in several or many, 
and thus frequently the conclusions which have been interpre- 
ted to be contradictory are really supplementary. To illus- 
trate : But few writers have assigned more than a single cause 
for crustal shortening. One has held that secular cooling is 
the cause; another has given a different one, and has held that 
secular cooling is of little consequence. But it is certain that 
isecular cooling, vulcanism, change of oblateness of the earth, 
change of pressure within the earth, changes in form of the 
material of the earth, and various other causes are not exclus- 
ive of one another, but are all supplementary. The ability to 
perceive the supplementary nature of various explanations of- 
fered for a phenomenon is one of the most marked, perhaps 
the most marked, of the 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 satis- 
factorily to solve the problems it must determine the quantita- 
tive importance of each. Geology within the next few years 
is certain to largely pass to a quantitative basis. 
