the sand to be slightly coarser at 210 to 250 micrometers. The mineral 

 content o£ the sand averages about 50-percent hornblende (Intersea Re- 

 search Corporation, 1978). Grain-size diameter is considered a parame- 

 ter of major biological importance (Jannson, 1967) . The most commonly 

 used grain-size parameter is the median grain size (Md) (Fig. 8). 

 Intertidal sediments (Md = 210 to 275 micrometers) were coarser than 

 offshore sediments. The sediment at 6.1 meters (Md = 84 to 110 micro- 

 meters) was finer than at 3.7 meters (Md = 125 to 165 micrometers). 



The intertidal sediments were finer (Md = 133 micrometers) during 

 survey III (2 June 1977) than during any other intertidal survey. The 

 large increase in fine sediments at the 3.7- and 6.1-meter impacted 

 stations indicated that some of these fine sediments were quickly 

 transported offshore (Figs. 8 and 9). The rapid recovery of intertidal 

 station B sediments following the termination of beach replenishment and 

 the lack of any measurable change in median grain size or percent of 

 very fine sand at intertidal station A also indicate how rapidly these 

 fine sediments are moved offshore. Five months after beach replenish- 

 ment the median grain size and percent of very fine sand for all sta- 

 tions had returned to values comparable to those found at the initiation 

 of the study. 



That longer lasting changes occurred in sediment parameters is 

 indicated by consideration of the coarse sediment fractions. The coarse 

 sand fraction was measured in two different ways. First, the percentage 

 of sand larger than 1 millimeter was calculated from sand-grain distri- 

 bution data. Secondly, the volume (milliliters) of coarse sand retained 

 on a 0.5-millimeter screen from a 0.5-liter core sample was measured. 

 An indication of the extent and persistence of coarse sediments in the 

 replenished area is shown in the coarse sediment volume for all core 

 samples taken at the intertidal stations (90 cores per station) for 

 survey V (Table 4) . 



Table 4. Total voliome of coarse sand (diameter larger than 

 0.5 millimeter) retained from 90 cores (45 liters) 

 per intertidal station, survey V, November 1977. 



Station Designation 



Volume 

 (ml) 



Volume sampled 

 (pet) 



A 

 B 

 C 



12,600 

 10,150 



2,745 



28 



23 



6 



35 



