Tropical cyclones - Extreme Events: A Physical Reconstruction and Risk Assessment - page 91

Figure 4.5. Beach ridge sequence at Cowley Beach, south of Cairns in northeast
Australia. Ridges and swales are differentiated by different coloured vegetation.
Swales are noted by a lighter colour where Melaleuca trees dominate. These ridges
are likely deposited by tropical cyclones. Photograph by Professor David Hopley,
James Cook University.
Elsewhere, cyclone built ridges have existed only as ephemeral features.
Coleman (1977)andTanner (1995)describe cyclone built ridges near Florida,
USA, which developed due to the accretion of an offshore bar and remained,
until their eventual erosion by subsequent normal wave action, as isolated fea-
tures separated from the mainland coast. Tanner (1995)arguesthat storm built
ridges do not survive and hence are not preserved in the recent geological record.
But the beach ridges from northeastern Australia suggest otherwise. Rhodes et al .
(1980)suggest that the more inland ridges along the Gulf of Carpentaria prob-
ably date to the Pleistocene, suggesting that a pre-Holocene record of tropical
cyclones may exist in this region. As yet, however, these ridges have not been
dated because they no longer contain shells due to their weathering and decom-
position over time.
Sand splays
Coastal sand dunes are often eroded, and diminished substantially in
height, when surge and waves overtop them. The eroded sand can be transported
inland as a splay or sheet that thins landwards. Similar deposits can also occur