Training of a Geologist. — Van Rise. 165 
work should include areal mapping- with structural and genetic 
interpretations. The more widely a young geologist has trav- 
eled, the more numerous the excursions in which he has taken 
part, the better will be his equipment. But no general work 
such as this can supply the place of systematic mapping. And 
the more exact the mapping is, the better the training. Very fre- 
quently the educational value of the mapping in detail of a small 
area is underestimated. Indeed, I hold that nothing else can 
take its place. Moreover, the only sure way to test a geolo- 
gist is to require him to delineate upon a map and in structural 
sections the detailed phenomena of the field. For my part I 
have more confidence in the future of a young geologist who has 
mapped in detail twenty-five square miles, and has got out of 
the area much that is in it, than that of another who has done 
no detail work but has run over and written about thousands 
of square miles. Rarelv can the general conclusions of a man 
who has not done systematic mapping be relied upon. In 
America there have been conspicuous cases of men calling 
themselves geologists who have never carefully mapped a 
square mile. Yet some of these by the undiscriminating have 
been regarded as leading geologists. And in one or two cases 
these men have gained a wide hearing. But the systems which 
they have built up have little or no relation to the world, and 
they have disappeared with the death of their authors. A geol- 
ogist must not only do systematic field work at the outset, but 
he must continue to do such work through the years to a rip- 
ened age. Not infrequently a geologist, who in early life has done 
systematic field work, drops this work and continues writing 
geological philosophy. This is a precarious course, which soon- 
er or later makes of him what one of our members calls a 
'closet geologist.' It is only by never ending action and reac- 
tion between the observation of complex phenomena of geology 
in the field and reflection as to the meaning of the phenomena 
that sure results can be obtained. 
While one should spend a part of each year in the field, I 
suspect that many more discoveries of geological principles 
are made in the office or in the laboratory than in the field. 
The cow collects the grass in the meadow and afterw'ards lies 
down to chew the cud and digest the food. So the geologist 
in the field, in the midst of iimumerable facts, collects all he 
