Tropical cyclones - Extreme Events: A Physical Reconstruction and Risk Assessment - page 85

however, requires much longer-term records than are often available from the
historical record alone. This is also the case for assessing risk to human commu-
nities from these events. In such situations the prehistoric record can provide
an invaluable insight into the trends and quasi-periodicities of tropical cyclone
behaviour for a region.
palaeotempestology and the prehistoric record
Palaeotempestology is the study of prehistoric tempests or storms. To
date this has been confined to the study of prehistoric tropical cyclones but
technically it could also apply to mid- and high-latitude events. Palaeotempestol-
ogists reconstruct past extreme events from sedimentary or erosional evidence
left in the landscape as a result of storm surge and wave action. It is a relatively
new branch of science which has, until recently, concentrated on the frequency
of prehistoric tropical cyclones in tropical Australia (Chappell et al ., 1983;Chivas
et al ., 1986;HayneandChappell, 2001, 2005), southern and eastern United States
(Liu and Fearn, 1993, 2000;Collins et al ., 1999; Donnelly et al ., 2001a, b)andto
alesser extent throughout the South Pacific islands (McKee, 1959;Bainesand
McLean, 1976; McLean, 1993). In some situations, the magnitude of these past
storms can also be estimated with reasonable accuracy (Nott and Hayne, 2001;
Nott, 2003). By determining both frequency and magnitude it is possible to ascer-
tain any quasi-periodicities in cyclone behaviour over the last 5000 years (Nott
and Hayne, 2001). The historical record of cyclones is often, but not always (see
Liu et al ., 2001 for 1000 year history in China), confined to the last 130 years
or less. The longer-term insights offered through the study of palaeotempests
allows more accurate risk assessments of the future impacts of these events to
coastal communities.
The prehistoric record of tropical cyclones is largely restricted to the latter
half of the Holocene, being approximately the last 5000--6000 years, or since ter-
mination of the Holocene marine transgression. While tropical cyclones would
have formed during the period of lower sea-level between the present and last
interglacials, any sediments deposited by these events are likely to have been
reworked during the Holocene sea-level rise. Last interglacial storm deposits are
probably also preserved in some locations, but to date no such deposits have
been positively identified.
Sediments deposited during tropical cyclones take the form of ridges of coral
rubble, pumice, shell or sand and shell, splays and sheets of sand incorporat-
ing marine microfossils, shells, coral fragments and lithic clasts, layers of sand
within otherwise muddy or organic sediments in back-barrier lagoons and shell
layers in fine-grained sediments in shallow marine environments. All of these