Q2 STUDIES FOR STUDENTS 
opment of grade depends on the spontaneous adjustment of the 
capacity of a river to do work, and the quantity of work to be 
done by the river. It is well understood that this adjustment is 
realized by the larger streams relatively early in the cycle; by 
those of medium and smaller size at later and later stages; and 
hence that the condition of grade is deliberately introduced and 
systematically extended through all parts of a river system as 
the cycle advances. The condition of grade needs no mention 
when the scheme of the cycle is first presented. Truly, it might 
be considered as an accompaniment of the youth of a cycle in 
those special cases where a large river is running across a slowly 
rising region of weak rocks, for here the condition of grade may 
be continuously maintained during the period of uplift. But it 
is not in connection with special cases of this kind that a first 
acquaintance with the condition of grade is best made. Its 
fuller meaning is not likely to be well understood unless pre- 
sented with something of the deliberation that characterizes 
the actual development of graded rivers. Indeed the concep- 
tion of grade is likely to be an embarrassment if presented too 
early. 
_ The extension of the graded condition over all parts of a 
river system introduces a thoroughness of organization in the 
processes of land sculpture that warrants the use of the term 
‘‘maturity,’ as the name of the stage of the cycle in which 
the organization of river systems is chiefly accomplished. The 
growth of organization goes with the development of grade. 
In every reach of a river in which the graded condition has 
been attained, the lowest point on the reach is always coinci- 
dent with and dependent on a controlling baselevel (as above 
defined) either general or local, and river action at any point 
in the graded reach is then delicately correlated with that at 
every other point. River action in such a reach may justly 
be said to be organized, inasmuch as a change in form or 
action at any one point involves a change at every other point. 
Adjacent reaches, separated by a fall on an ungraded ledge 
. or by an unfilled lake, are independently organized; a change 
