22 
THE DEPARTMENTS OF GEOGRAPHY. 
MILL LONDON. 
BY HUGH ROBERT De Sey, 
} 
Tue sub-division of any portion of science must be 
largely empirical, and in accordance rather with prac- 
tical convenience than with natural planes of cleavage. 
Thus we are accustomed to such phrases as mathemati- 
cal geography, physical geography, astronomical geo- 
graphy, ancient geography, political geography, and 
the like, although it would be very difficult to piece to- 
gether the fragments which pass under these names so 
as to make up a coherent geography. __In endeavoring 
to sub-divide the content of geography in such a way 
as to bring out the natural interrelations of its parts 
and their logical sequence, for purposes of exhaustive 
study, it has occurred to me to represent the whole 
metaphorically by a pyramid of several courses of ma- 
sonry differing in material and finish but each sup- 
ported by those below and supporting those above. 
Thus the fundamental course would be mathematical 
geography, constructed of great blocks hewn from the 
quarries of the only absolute science, accurately squared 
and fitted. 
measurement of space and time and motion, the form 
and dimensions of the earth, its motions and the con- 
struction of maps. Upon this baseis reared the second 
tier, physical geography, the material for which, less 
homogeneous and perfect than the foregoing, comes from 
quarries scattered over the realms of many sciences, 
from chemistry, physics and the different departments 
of geology, from meteorology and the science of the 
oceans. It is concerned with all these phenomena 
which depend on differences of substance, structure and 
state, and accounts for the origin of surface features 
and of scenery, the interactions of lithosphere, hydro- 
sphere and atmosphere and the effect on each of solar 
energy. Next in order and less regular in structure, 
dependent on physical geography as physical is on 
mathematical, I place bio-geography, wherein the influ- 
ence of life is taken into account. This serves to ex- 
plain how vital processes of plant and animal affect 
the structure of the earth, and how the lifeless 
features of the globe regulate the distribution of vege- 
tation and of animals. Arising directly from this floor, 
but as yet only imperfectly put together, is the course 
of anthropo-geography, the elucidation of the action of 
mankind as an animal species upon the globe. The 
unit of consideration is mankind as a whole; the variety 
of races, conditions of life and density of population 
are the features taken into account, and the interaction 
between man and nature has to be studied in its widest 
aspects. The changes in the relation of different tribes 
to their habitat belong to this zone, and these changes 
are the basis of historical geography, which gives origin 
to the next tier of our pyramid, in which the influence 
of races of men on the earth finds a place. This may 
be termed, for lack of a better name, political geo- 
graphy; itsunits are uncertain and transitory, for the 
hold of nations on regions is subject to continual 
change. But political geography is stability itself 
compared with the rough pile of commercial geography 
which caps if it does not crown the edifice. Here it is 
no longer the racial or national view-point which deter- 
mines the conditions, but the individual greedy of gain 
or struggling for life. The distribution of natural re- 
sources is the fundamental condition, and the national 
frontier has rarely much in common with the political. 
But here a further simile must be brought in. This 
cap of the pyramid plays the part of a keystone as well, 
and binds the whole structure together. As rain filter- 
ing through a mass of brick or stonework dissolves the 
SCIENCE. 
It includes all that has to do with exact . 
[Vol XXIII. No. 571 
mortar of the upper parts, andredeposits it in the lower 
courses, so the stream of self-interest permeates the 
whole structure of geography, and its results are felt 
throughout. Commercial motives consolidate national 
life, accentuate racial differences, redistribute animals 
and plants, modify physical conditions, start investiga- 
tions into the nature of the earth, and even invade the 
solid groundwork of mathematics with the practical 
counsels of common-sense. 
There are many people, but there were more, who 
deny to the sphere of geography anything beyond the 
measuring of distances and the mapping of distribu- 
tions. The legitimate scope of the science, however, 
includes very much more, and the simile which I have 
sketched may help sorme students to understand and 
some teachers to apply the principles of geography. 
THE AGE OF THE IRON ORES OF EAST 
‘TEXAS.’ 
BY WILLIAM KENNEDY, AUSTIN, TEXAS. 
EXTENSIVE deposits of brown iron ore, or limonite, 
occur throughout east Texas, from the State line west- 
ward to the Brazos River, and covering a roughly irreg- 
ular triangular area, having its base resting upon the 
Snlphur Fork of the Red River across the northern side 
of Cass County and extending westward until the apex 
touches the Brazos. 
Regarding the age of these deposits considerable 
confusion appears to have arisen. In the Tenth 
Census Professor Pumpelly assigns them to the 
Quaternary. Why this age was given to these ores is 
not stated. They simply appear among the Quaternary 
deposits in the Texas section shown on plate VIIL., of 
the fifteenth volume, and no mention is made anywhere 
in the text of any authority for so placing them. As 
the only Texas ore of which any notice is taken in this 
volume is that found in Marion County, and then 
worked in the Kelleyville furnace, it may be presumed 
that, as that ore is of the nodular variety and corres- 
ponds very closely in physical appearance and approxi- 
mately in chemical composition to the ores found in 
Mississippi by Dr. Hilgard and described by him as be- ~ 
longing to his Orange Sand formation, and consequent- 
ly of Quaternary age, Professor Pumpelly considered 
the Marion County ores to have the same origin and 
date, and so placed them in the Quaternary when mak- 
ing his section. 
The next investigator was Mr. Lawrence C. Johnson, 
an Assistant on the United States Geological Survey. 
Mr. Johnson had been assigned to make an examina- 
tion of the iron ores of northern Louisiana in 1885, 
and in 1886 his instructions were modified and ex- 
tended so as to enable him to examine the east Texas 
deposits. This investigator appears to have been the 
first to recognize the existence of two divisions among 
the ores. ‘hese he separated, assigning the name of 
nodular ore to the one variety, and by the term Jacus- 
trine designated the other. This latter class he again 
divided into ‘‘laminated” and ‘‘buff crumbly” ores, ac- 
cording to their texture and physical appearance. 
While dividing the ores into these two great divisions, 
he at the same time placed them in different ages and 
under entirely different conditions. The nodular ore, 
Mr. Johnson considered as belonging to the lignitic 
Tertiary, and we find him, after describing the ores of 
Marion County, saying: ‘‘All thisportion of the iron 
field, including Upshur, Camp, Morris, Marion and 
Cass Counties, is assigned tothe great Lignitic of the 
Geological Column.” (Iron Ores of Northern Louisiana 
and Hastern Texas, Ex. Doc. 195, first session, Fiftieth 
Congress, p. 34.) 
1Read before the Texas Academy of Science, Dec, 16, 1893. 
