GEOGRAPHY: W. M. DAVIS 
285 
pie shoreline may be at first somewhat prograded by the deltas of the 
larger streams, sector K of the figure; between the deltas it may be some- 
what retrograded and cHft by the waves; but an abundant supply of 
cobbles, gravels and sands from the delta fronts will be swept along the 
inter-delta shores in the form of beaches that will cover the cliff-base 
platforms; and the finer sediments will be spread seaward on the sub- 
marine flanks of the volcanic mass. The deltas, the beaches and the off- 
shore sediments will form a detrital sheet, thickest and of coarsest tex- 
ture on the deltas, of finest texture and for a time thinnest where it slopes 
into deep water; but as time passes, the fine- textured, off-shore sediments 
will come to exceed all other parts of die detrital sheet in thickness, for 
when retrogradation begins and the deltas are cut back in the general 
retreat of the shoreline, sectors L, M, N, the stream-mouth deposits will 
be hardly thicker than the cliff -base beaches. Small patches of fringing 
reef may at first form on the bare unreduced ledges that here and there 
protrude through the cliff -base beaches; but elsewhere the materials of 
the detrital sheet are too commonly in movement to permit coral growth. 
After volcanic eruptions have definitively ceased and the normal dis- 
section of the cone by weather and streams and the cutting of cliffs 
around the simple shore by waves are further advanced, it is probable 
that the first formed reef patches will be overwhelmed by the increasing 
continuity of the detrital sheet, and if this unfavorable condition for reef 
