GEOLOGY: W. M. DAVIS 
277 
later cycle of erosion introduced by elevation; the removal thus initiated is still 
continued in spite of the still later subsidence. 
The general sequence of changes by which the present form of the island 
has been evolved from a subcontinental land of Tertiary or earlier time may 
be outlined as follows. A composite land mass of large, perhaps continental, 
extent, consisting hereabouts of deformed crystalline and Mesozoic rocks, was 
eroded to mountainous or moderate relief, AB, in the background block 
of figure 1 ; it was then reduced in area by down-warping, probably in tertiary 
time, whereby the surviving land area must have gained an embayed shore line, 
C, D, as in block 2. If coral reefs had previously existed around the border 
of the larger land, they must have been drowned by rapid submergence, for the 
FIG. 1. THE PHYSIOLOGICAL DEVELOPMENT OF NEW CALEDONIA 
adjoining seas are very deep. New reefs may have been formed in the later 
stages of submergence, enclosing a lagoon, C. 
The reduced island of block 2 must have stood still long enough to suffer 
reduction to small or low relief, except in its areas of most resistant rocks, as 
in block 3 ; the serpentine areas were mostly reduced to peneplains at this time. 
The embayments formed in the shore line at the beginning of this cycle of 
erosion were presumably in time filled with deltas that advanced into the 
reef-enclosed lagoon, as at E; the deltas may indeed have grown so far as to 
overwhelm and smother the reef, whereupon it would be cut away by the waves 
which would in time attack the worn-down land, retrograding its peneplains 
in low cliffs and spreading the detritus from them and the rivers on the 
shallow floor of the adjoining sea, F; for this change from a reef-fronted and 
prograded coast of submergence in an early stage of an erosion cycle that 
