observations, even though encumbered by noise, can be used effectively 
to test the applicability of the model. Surface-fitting functions other 
than polynomials will very likely come increasingly into use as the 
physical processes underlying a given beach model are better understood. 
Interest is developing in what have come to be called "secondary trend 
components" (Allen and Krumbein, 1962), that probably represent some or 
all of the terms in surfaces of relatively high degree. 
ADDENDUM 
Since this report was written, additional computer time was obtained 
for the construction of cubic trend maps for the data from the three pier 
transects of Figure 5. By subtracting these cubic trend surfaces from 
the Mz and So cubic trend surfaces (Figures 13 and 19) for the inlet 
entrance, the maps of Figures 21 and 22 have been obtained. They indicate 
the pattern, magnitude, and limit of inlet influence on the Mz and So 
patterns of the beach. 
