subsequent high-energy storm conditions, and that cementation of the pipes 

 by either limonite or calcite had occurred. No geochemical analysis of 

 the cementing material wbs made. 



2. Jupiter . 



The beach width on the two Jupiter profiles from the toe of the 

 frontal dune to the MSL shoreline ranged from a minimum of 50 feet (Feb- 

 ruary 1972) to a maximum of 180 feet (55 meters) (February 1969). The 

 average berm elevation was 6.9 feet (2.1 meters). The average monthly 

 foreshore slope ranged from 8° to 12°, with an overall average foreshore 

 slope of 10° (1 on 5.7). The maximum elevation change at any station was 

 8.5 feet (2.6 meters) of accretion at pipe 3 (south row) between June 

 1972 and February 1973 during which period a gain of 27.5 cubic yards 

 (69.0 cubic meters) of sand per lineal foot of beach was measured. 



a. Short-Term Changes . A total of 223 sets of profile surveys was 

 made at Jupiter, averaging once each 7.4 days over the study period. 

 Changes between surveys in the MSL shoreline position and in the beach 

 volume above the MSL elevation are presented in Appendixes F and G. The 

 changes are referenced to the shoreline position and volume of the sub- 

 aerial beach at the first survey in January 1969. Positive slopes on the 

 plotted curves indicate either progradation or accretion; negative slopes 

 indicate erosion. 



The average change in the MSL shoreline position between weekly sur- 

 veys was approximately 9 feet (2.7 meters) in either a landward or sea- 

 ward direction. The average volumetric gain between weekly surveys when 

 accretion occurred was 1.1 cubic yards per foot (2.8 cubic meters per 

 meter) of beach; the average loss was 1.3 cubic yards per foot (3.3 cubic 

 meters per meter) . 



Significant short-term changes were generally associated with ob- 

 served periods of high wave activity, but were not necessarily associated 

 with local storms. Shoreline and volumetric changes associated with three 

 specific storms are listed in Table 4. The largest loss (an MSL shoreline 

 retreat of 63 feet C19-2 meters) and volume loss of 12.6 cubic yards per 

 foot (31.6. cubic meters per meter)) were observed at profile line II (south 

 row), between surveys on 23 and 3Q March 1972. These losses were confirmed 

 by the observations recorded in the fieldbook on 30 March that the erosion 

 was "most unusual this week . . . entire beach in front of pipe profile is 

 now mostly rock." However, unusual wind velocities, wave heights, or long- 

 shore currents were not observed at the site during either of the two sur- 

 veys. There was also no indication from the LEO or COSOP data of higher 

 than normal wave activity at Boca Raton or Hillsboro during the same 7-day 

 interval. The Lake Worth wave gage was not operational during this time 

 period. 



The largest accretion measured between surveys occurred 8 to 15 

 June 1972, a gain in the MSL shoreline of 81 feet (24.7 meters) and a 



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