Australian Coastal Geodiversity And A Tribute To Andy Short

Paul Donaldson kindly reminded me that 6 October is UNESCO International Geodiversity Day. In advance of that day he prompted me to say something about Australian coastal geodiversity. This also offers me the opportunity to pay tribute to the one person who has provided the most comprehensive review of Australian coastal systems and in doing so its geodiversity. Andy Short has written many papers, reviews and books on various aspects of the Australian coast. For the purposes of this blog I will refer to two books: The Coast of Australia with Colin Woodroffe (Cambridge University Press, 2009), and Australian Coastal Systems, Beaches, Barriers and Compartments (2 volumes, Springer, 2020). Both are extraordinarily well-illustrated and anyone interested in an overview of the geomorphic/geodiverse treasures of our coast should consult them. I frequently do.

The theme of the Geodiversity Day this year is “Conserving the Past—Sustaining the Future”. It recognizes (1) sites of particular significance or geoheritage; (2) how geodiversity can play a role as a record of past events through assisting decision makers in adapting to geological hazards; and (3) where stunning landforms can help underpin a growing geotourism industry. Here I will try to capture some aspects of this theme, resisting the temptation to document in any detail the locations that I refer to (in most cases Andy has already done that including references).

As a coastal nation most of us know and favour certain sites and these sites have over time become meccas for tourism. Some already have World Heritage status such as K’gari (Fraser Island), Shark Bay, Ningaloo, Lord Howe Island and of course the Great Barrier Reef and all its islands. These are noted for a range of both geo and bio attributes. In all cases there have been battles to achieve international recognition (see Blog 137, May 2019 on John Sinclair and Fraser Island). Even to achieve national or regional park protection there have been many occasions requiring brave advocates who have cited geo values in the cause (e.g. Myall Lakes in the 1960-70s). But there is little doubt that where progressive forces have won out there has been huge appreciation of those landscape values which reflect our geoheritage/geodiversity.

The following is a personal perspective on places that possess various coastal geodiverse values covering different time and spatial scales. Those of more ancient vintage (perhaps even late Cretaceous to early Cenozoic) link back in time to the opening of seas around our continent including the majestic cliffs of southeast Australia (Beecroft Peninsula, Tasman Peninsula) and along the southern coast (Port Campbell, Nullarbor). In the west the Zuytdorp cliffs reflect more recent geological episodes. Incised and indented rocky coasts of southwest Tasmania and the Kimberleys offer suites of landforms reflecting long-time scale responses to different sets of processes at a regional scale demanding further study. And then there are those areas across southern Australia south of the “Sandiford Line” (Eucla Basin/Nullarbor Plain and southern Murray Basin) which assist in our understanding of the “tilting continent” and Cenozoic depositional sequences (see Blog 141, July 2019).

The late Quaternary is well represented in Australian coastal landscapes. These are important as they provide those insights into the past which we can use to better understand the future. Improved ways of measuring episodes of sediment deposition have opened windows into these periods when conditions were both similar and different from the present. Radiocarbon and other dating tools in the 1970s-80s provided basic chronologies, for instance in areas north of Newcastle and on the South Alligator River flood plain. However, OSL dating offered a new level of precision that expanded this work in various places ( e.g. Gippsland, Robe area). So we can look at dune fields of Cooloola or the incredible strandplain of Robins Island (NW Tasmania) with new eyes now we have well-dated sequences. Holocene strandplains and dunes have been the subject of study in many places and records such as we have in NSW at Disaster Bay and Moruya are at a resolution that enables us the see what has happened even over the last few centuries. These are places that require recognition and protection for what they are revealing given that they are areas little disturbed by human activity. Their chronologies can be tied to present-day beach monitoring as at Bengello Beach, Moruya.

I am taking the liberty of listing 12 favourite geodiverse sites which I have visited and worked on at some stage. They are in no particular order.

Sandstone cliffs and rock platforms of Sydney coast.
Mobile and stablised dunes of Stockton Bight and Myall Lakes, NSW.
Holocene and Late Pleistocene strandplains north of Port Stephens, NSW.
Largs last interglacial “geoheritage” site lower Hunter, NSW (see Blog 194, July 2021).
K’gari, especially northern end, Qld.
False Mouths of the Ord River; tidal flats and mangroves, WA.
Cheniers and tidal rivers of Gulf of Carpentaria, west of Karumba, Qld.
South Alligator River flood plain and cheniers, NT.
Bengello Beach and strandplain with relic cliffs, Moruya, NSW.
Ninety Mile Beach and associated backbarrier features, Victoria.
Younghusband Peninsula and Murray Mouth, SA.
Bewick Island, north of Cooktown, GBR.

There are stories attached to each of these places, stories of adventure, discovery, excitement, joy and comradeship. They capture times of drilling, diving, monitoring, mapping, travelling and engaging with colleagues like Andy. In their own way each highlights important aspects of geodiversity. But an ongoing story awaits resolution.

Between Kiama and Gerroa on the NSW south coast is a stretch of coast carved into a diverse sequence of Permian sediments and volcanics. With the help of the then Kiama Council I assisted in securing a walking track along the cliff line with the help of state funds from the NSW Coastal Lands Protection Scheme. It now attracts many tourists to enjoy its geo wonders, but only as far as Gerringong. In recent years we have sought the engagement of the present council to complete the walk to Gerroa from Gerringong that picks up another part of the rock sequence with its beautiful rock platforms. One can hope the recent local government election will prompt action. Peter Stuckey was one of the stalwarts who fought hard for the initial track and then its extension. Sadly he recently passed away; he will be greatly missed as he understood the value of geodiversity. Vale Peter.

I would like to invite readers to name their favourite places which capture the theme of Geodiversity Day. Let me know your favourites. Like Paul Donaldson, I am fascinated in what ways the study of geomorphology of different places is contributing to our geoheritage and geodiversity. We owe so much to Andy Short in providing details for our entire coast, but those of us less privileged to visit so many places will have our own sites that we want to see preserved and from which we can continue to learn.

Bruce Thom

Words by Prof Bruce Thom. Please respect the author’s thoughts and reference appropriately: (c) ACS, 2024. For correspondence about this blog post please email admin@australiancoastalsociety.org.au

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