Australia: The Land Where Time Began

A biography of the Australian continent 

A 6,000 Year Record of Tropical Cyclones in Western Australia

In this paper the authors¹ present the results of their study that is the first long-term tropical cyclone record in the Indian Ocean region. At Hamlin Pool, Shark Bay, Western Australia, there are multiple parallel ridges that are composed almost entirely of a single species of marine cockle shell, Fragum eragatum, that stand at 3-6 m above mean sea level. A history of tropical cyclones covering the period from 6,000-7,000 cal BP to about 500 cal BP is recorded by the ridges. Numerical modelling of storm surges and shallow water waves were applied to determine the intensity (central pressure with uncertainty margins) of the storms that formed the ridges which has occurred about every 190-270 years. Also recorded by the ridges is a gap of 1,700 years in the activity of tropical cyclones, that occurred from about 5,400-3,700 cal BP, the ridges formed before this period being buried during this period by a substantial deposit of terrestrial aeolian sediment that was fine-grained. A very dry climate lasting 1,700 years is suggested by the presence of this sedimentary unit, which is suggested by the authors¹ to be the driest phase in this region since the mid-Holocene. They also suggest the absence of tropical cyclones at this time may be linked to this mega-drought.

Sources & Further reading

1. Nott, Jonathan. "A 6000 Year Tropical Cyclone Record from Western Australia." Quaternary Science Reviews 30, no. 5–6 (3// 2011): 713-22.