156 The American Geologist. September, 1902 
^ome of those who call themselves professional geologists, 
are teachers of geology in academies and colleges, or even 
members of the staff of state or government surveys. These 
men have gone further than the local geologist, but perhaps 
they have been led into the subject for somewhat the same rea- 
son; — its easy start as an observational science. A man may 
begin his career as a geologist by making a few observations 
here and there and giving a guess as to their meaning. With 
this beginning he becomes more and more interested, until 
finally he decides to make geology his profession. 
In some cases, following this decision, the necessity is seen 
for obtaining a working knowledge of the basal sciences. But 
too often men who have entered upon geological w^ork have 
received no adequate training in chemistry, in physics, in 
biology, and therefore at the outset wholly lack the tools to 
successfully interpret the phenomena which they observe. 
Such inadequately trained men feel that a satisfactory explana- 
tion of any phenomenon must involve a statement of the un- 
derlying chemical or physical or biological principles, and in 
such cases it is safe to say that the explanations given are 
extremely partial, including only a modicum of truth, and more 
often than not are absolutely fallacious. Indeed, no other re- 
sult can be expected from one who lacks a working knowledge 
of the principles of physics, chemistry, and biology. Occas- 
ionally there is a clear-sighted, capable man, lacking in ade- 
quate training, who does important geological work simply be- 
cause he knows his limitations, and there stops. But this is 
very exceptional indeed ; and the physical explanations offered 
by many for various geological phenomena are no less than 
grotesque. 
It has been made plain that a working knowledge of the 
sciences basal to geology is necessary in order to advance its 
principles. But I go even further, and hold that such basal 
knowledge is absolutelv necessary in order to do even the 
best descriptive work. Suppose a man to be standing before 
some complex geological phenomenon. The whole intricate 
interlocking story is engraved upon the retina of his eye with 
more than photographic accuracy. The image on the retina 
is 'absolutely the same in the eye of this experienced geologist 
and that of a child. Yet if the child be asked to state what he 
