Geography In the United States. — Davis. \ycf 
be noted in this connection that the appHcation of the explan- 
atory method has been so lately made to the treatment of land 
forms that the geographer may for the present make himself 
to his advantage something of a specialist in this branch of 
the subject. It should be added that, so long as he studies land 
forms in order better to understand the environment in which 
living things find themselves, he remains a geographer and does 
not become a geologist. There is a needless confusion in this 
matter, which may perhaps be lessened if its untangling be il- 
lustrated by the following geological comparison. 
For some decades past a new method of treatment has been 
applied to the study of rocks, greatly to the advantage of geol- 
ogists. The method requires a good knowledge of inorganic 
chemistry and of optical physics, and the geologists who have 
specialized in the study of rocks have had to make themselves 
experts in these phases of physics and chemistry ; but they are 
not for that reason classified as physicists or chemists. They 
remain geologists, though sometimes taking the special title of 
petrographer. So with the geographer who specializes in the 
study of land forms ; he must make himself familiar with cer- 
tain phases of geology, but he does not therefore become a geol- 
ogist; he remains a geographer. His object is not to discover 
for their own sake the past stages through wdiich existing land 
forms have been developed : he studies past forms only in order 
to extend his knowledge of systematic physiography and thus 
to increase his appreciation of existing forms. As far as he 
studies the sequence of past forms he is studying a phase of 
geology, just as the geologist who examines existing arrange- 
ments of climate, or oceanic circulation, or of land forms, is 
studying a phase of physiography. The two sciences are man- 
ifestly related, but they need not be confused. For, as has 
been shown for sciences in general, geology and geography 
are best characterized by the relations in which their topics 
are studied and not by the topics themselves. Both are con- 
cerned with the earth and life. The whole content of knowl- 
edge concerning the earth and life might be shown by a cube, 
in which vertical lines represented the passage of time, and 
horizontal planes represented phenomena considered in their 
areal extension ; then if the whole mass of the cube were con- 
ceived as made up of vertical lines, that would suggest the geo- 
