IBA SV BILSS Jed Moy (CIMA OVE, AISI ONS CA PANIIT EI LING 81 
Marr does not use the term ‘‘baselevel,’’ but says instead : 
A river which has established equilibrium ... . is said to have reached 
its base-line of erosion, and no further work of erosion or deposit can occur 
until the conditions are changed (84). 
Dryer states: 
The lower Mississippi has reached its baselevel, or the lowest level to 
which its current and load will permit it to reduce its bed..... In the 
lower reaches of a river the valley is soon cut down to baselevel, where the 
slope is gentle and the current too slow to carry the full load of sediment it 
receives. Deposition occurs and downward corrasion ceases (79, 154). 
Powell makes the following statement in a discussion of 
reaches and rapids: 
The slow reach is a baselevel, like that of a lake, below which the banks 
and hills on either side cannot be degraded (1894, 35). 
Various other definitions, more or less aberrant from the 
original and discordant with each other, are found in the follow- 
ing citations: 
Dutton took baselevel to be a condition: 
The condition of baselevel is one in which the rivers of a region cannot 
corrade. Asa general rule it arises from the rivers having cut down so low 
that their transporting power is fully occupied, even to repletion. .... The 
recurrence of upheaval terminates the condition of baselevel (224, 225). 
According to Willis baselevel is a slope: 
A baselevel is the lowest slope to which rivers can reduce a land area 
(1895, 189). The ideal lowest possible slope, which is called a baselevel, is 
perhaps rarely reached (1900, 27). 
Hayes makes baselevel a mathematical plane: 
The term baselevel, synonymous with baselevel of erosion, is [here] 
restricted to Powell’s original use . . . . the general baselevel being sea level. 
There may be an indefinite number of /oca/ baselevels in any region, each 
being determined by the outlet of the stream whose drainage basin is con- 
sidered; but only one geseral baselevel..... It should be clearly under- 
stood, then, that a baselevel is not a topographic form, but a mathematical 
plane, which may or may not, and generally does not, coincide with a land 
surface (21). 
When describing erosion by rivers, Scott writes: 
A stage must sooner or later be reached when the vertical cutting of the 
stream must cease. This stage is called the baselevel of erosion or regimen 
