Dependency

Fig. 11.14. Precipitous cliffs, like these in Cenozoic volcanic breccias south of Cape Adare, North Victoria Land, would self cleanse rapidly even when not protected by ice.

Fig. 11.13. Frequency bar graph illustrating proportions of each coastal type for the region shown in Fig. 11.12. Seasonal, ice-free shores are far more common in this region than they are for most of the continent with the exception of the Antarctic Peninsula region.

Fig. 11.14. Precipitous cliffs, like these in Cenozoic volcanic breccias south of Cape Adare, North Victoria Land, would self cleanse rapidly even when not protected by ice.

eries (Fig. 11.15). Once the protective ice-foot disintegrates and disappears from these beaches in summer, they would be wide open to oil spill contamination. In the porous, coarse gravels of the intertidal zone and wave-swept active beach face, stranded oil could rapidly penetrate, possibly to the depth of the impervious ice or permafrost core. It could also be buried by rapid changes in beach morphology induced by wave action or ice-push. The irregularly hummocky relief and large hollows left by melting blocks of stranded ice would also provide sumps for the oil. Preliminary estimates suggest vast quantites of oil could be retained in these beaches (Table 11.4) to be released slowly by sediment redistribution and erosion over subsequent decades. Repeated fouling long after the spill occurred is likely. Recent observations following an experimental oil spill on a sheltered beach at Cape Hatt, Baffin Island in the Canadian Arctic (cf. Owens et al., 1987; Owens and Robson, 1987) suggest that, on seasonally exposed Ross Sea beaches, oil will be removed more rapidly and in more substantial quantities than this writer has previously envisaged (e.g., Gregory and Kirk, 1983).

Storm wave action would probably throw oil high on to and across seawards-most ridges of cuspate forelands (Fig. 11.15) leading to ashphaltic pavement formation and progressive immobilization of gravelly sediment. This could well enhance the erosion evident at the southern ends of most Ross Sea beaches as well as reduce pebble availability for penguins' nest building activities (Kirk and Gregory, in press).

Fig. 11.15. Cuspate foreland with raised beach ridges on Possession Island, off North Victoria Land Coast, and with its modern gravelly beach almost continuously protected by an ice foot. There are an estimated 100-150,000 breeding pairs of Adelie Penguins at this locality (Harper et al., 1984).
0 0

Post a comment