May 3, 1912] 
geologists, especially those who have given 
much attention to soils, for example, G. P. 
Merrill. These are (a) general weather- 
ing which gives rise to residual material. 
The type of weathering and the activity of 
the several forces will depend upon the 
kind of rock. (6) Decay acting upon or- 
ganic material to give rise to cumulose de- 
posits. It differs from weathering, since 
there is an actual building up of material 
due to biological activity and biological 
changes are dominant. These two groups 
taken together have been termed the seden- 
tary division, since the material has not 
been appreciably moved. Where rocks are 
involved the soil is likely to rest on rock of 
the same kind as that from which the soil 
was formed. The physical as well as the 
chemical properties of the rock maintain 
much of their identity in residual soil— 
for example, quartz bands in gneiss rock 
and chert masses and other impurities in 
the different strata of limestone. 
The remaining processes involve appre- 
ciable transportation of the material and 
have been grouped together as the trans- 
ported division. Four great agencies of 
transportation are recognized. 
(c) Gravity produces the slow sliding of 
material down rather steep slopes and in 
some instances it includes avalanche move- 
ment. The material is without organized 
structure and likely to be rather coarse and 
thin and of low agricultural value in both 
extent and adaptation. 
(d) Water has been the great transport- 
ing and soil-forming agency. Many of the 
most famous agricultural portions of the 
earth owe their formation to water, notably 
the Nile Valley, the American coastal plain 
and the interior lake plains and stream 
valleys. It couples a wide range of trans- 
porting power with very decided sorting 
® Merrill, G. P., ‘‘Rocks, Rock-weathering and 
Soils,’’ pp. 411, 1897, Macmillan Co., N. Y. 
SCIENCE 
683 
and in the deposit of the material produces 
stratification. Thereby nearly all of the 
areas of soil of distinct textural unity have 
been derived. Fine clay and clean, uni- 
form sand are equally identified with the 
agency of water. Stratification implies 
differences in successive layers, and a shift 
in the direction or velocity of movement of 
the water when a material was being laid 
down may produce great variation in tex- 
ture, structure and chemical composition. 
These principles of variation are so well 
understood that much explanation is un- 
necessary. 
It is worth while to recognize three 
phases of action of water according to its 
breadth, extent of movement and to some 
degree its character. These are oceans 
(saline waters), lakes and streams. The 
depth, uniformity and chemical character 
of the soil formed under each of these in- 
fiuences are likely to be distinct. While 
water gathers rock material from many 
sources, each body is likely to have certain 
characteristics of its material due to the 
region drained. 
(e) Ice in the form of glacial masses 
has been an extensive and important agency 
of soil-formation adjacent to the polar re- 
gions and in high mountains. Some of the 
most famous agricultural portions of the 
world, such as much of the Upper Missis- 
sippi River Valley owe their character to 
this agency. Here again peculiar chem- 
ical, physical and, to some extent, topo- 
graphic features are imparted to the ma- 
terial handled. The kind of rock encoun- 
tered, the rate and direction of movement 
of the ice and the minimum of chemical 
decay and leaching have determined the 
agricultural features of many regions 
formed by glacial ice. The soil conditions 
in New York State especially exemplify 
these distinctions. 
Ice does not accomplish sorting or strati- 
