Figures 73 and 74 emphasize the importance of the location of the 

 low-pressure system in relation to Plum Island in terms of storm inten- 

 sity. The peak wind and wave energy conditions occurred between 2:00 

 p.m. and 6:00 p.m. on 19 February while the center of the low was near 

 Long Island. The predominant wind pattern is onshore (Fig. 73) when the 

 low is south of Plum Island. As the low-pressure system moves northward, 

 the intensity of the storm diminishes on Plum Island and the winds asso- 

 ciated with the low become dominantly offshore. 



Poststorm Conditions. 



The large volume of sediment removed by the northeaster of 19 Febru- 

 ary is shown in F.igures 75 and 76. The erosion at PL-0 was concentrated 

 in the area between the low tide terrace and the foredune ridge with 

 little erosion on the low tide terrace (Fig. 76) . The same concentrated 

 zone of erosion is shown in Figure 75; however, there is a steep dune 

 scarp at PL-6 but not at PL-0. This tendency toward greater erosion in 

 the central part of the study area may be related to the character of the 

 offshore bar which is farther offshore and deeper in the central area. 



Photos in Figures 77 and 78 show conditions near the study area 

 immediately after the storm; Figure 77 was taken from PL- 2 looking south 

 toward PL-0 and PL-1, and shows a small washover in the foreground of the 

 photo. Larger washovers on other parts of Plum Island breached the 

 entire width of the island. The amount of landward erosion is noted by 

 the two stakes (not visible before the storm) in the center of the photo 

 (Fig. 78). Stumps exposed by the storm are also shown in the figure. 

 Damage to Plum Island was most extensive to the north of the study area 

 (Figs. 79 and 80). Heavy mineral concentrations at the base of the dune 

 scarp are visible in the top photo in Figure 79 along with evidence of 

 offshore winds in the form of snow and newly deposited sediment on the 

 beach face. The height of the swash reached on the foredune ridge is 

 shown in the lower photo (Fig. 79) . In areas of such concentrated ero- 

 sion, slumping continued for several days after the storm had passed. 

 The physical damage to dwellings at the northern end of Plum Island is 

 shown in Figure 80 . 



Two days after the storm, small ridges appeared on the low tide 

 terrace indicating the beginning of poststorm accretion (Fig. 81) . The 

 continued presence of offshore winds for several days after the storm is 

 shown by the breakers with blown tops in Figure 81. An aerial view of 

 the study area 3 days after the storm shows semicontinuous ridge and 

 runnel systems migrating landward. Erosive effects of the storm are 

 shown along the dune scarp and in the blowout in the extreme right of 

 the photo in Figure 82. 



Poststorm beach-face gradient changes were slower after this storm 

 than after the northeaster of 5 January 1972 (Fig. 83). The reason for 

 this slower change in gradient is directly related to the amount of 

 sediment removed after each storm. During the small northeaster in 



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