J JON TCQIRILALL. 
Ir would seem that there may be need to select for technical 
use suitable terms to specifically designate the critical factors of 
the sea border phenomena described in the first article of this 
issue. At least three agencies codperate in producing a struc- 
tural and topographic form which has a vital geologic function, 
and to which specific reference may frequently need to be made 
without descriptive circumlocution. The same may be said of 
some of the contributory factors and processes involved. The 
functions of these are more or less masked, and even antag- 
onized, by adventitious phenomena which need to be distin- 
guished and excluded. (1) There is first the building of the 
sediments into a submarine terrace. The plane toward which this 
terrace is built up is identical with that toward which the land is 
cut down. The two processes are complementary. The degra- 
dation of the one furnishes the material for the aggradation of 
the other, and their final result is a base-plain continuous with a 
terrace plain, both alike determined by the sea level. As the 
former process is called baseleveling, the latter might be desig- 
nated base-terracing and the result a base-terrace, but these 
terms are not altogether felicitous, because dase inevitably carries 
the idea of something beneath rather than above, and cannot 
perhaps easily be made to convey the conception of an over- 
lying plain to which aggradation approaches, and in which it 
finds its summit limit. A happy term for a summit plain to 
which aggradation is limited just as degradation is limited to a 
base-plain does not as yet suggest itself. (2) There is next the 
cutting landward of the sea edge, whereby the sea shelf is 
extended at the expense of the land. This is essentially a base- 
leveling process, and as such perhaps needs no other term than 
baseleveling, except as qualifiers may occasionally be required 
to indicate the particular mode of its action. (3) Then there 
524 
