The Future History of Adelaide: Earth, Continent, Bioregion
This ‘future history’ of Adelaide was based on ‘Los Angeles: A History of the Future’ (1982) by Paul Glover, and is written from the year 2136. It examines how Adelaide became an ‘ecopolis’ — an ecological city — over 150 years, reversing the damage done to the region since European colonisation began in 1836. At the time, there was a proposal for a ‘piece of ecocity’ in Halifax Street, whose features and design principles are referenced as the first fractal of this change. This larger scale proposal did not eventuate, but a smaller scale exemplar, Christie Walk, can be found in the CBD at 105 Sturt Street, Adelaide.
This was written in 1995 at university, as a directed study for history, and reflects my thinking, understanding, available technologies and references at the time. The Ecological Crisis of the 1990s is referred to as ‘EC’ and phrases like ‘200 years EC’ mean 200 years after this Crisis.
Earth, Continent, Bioregion
The Tandanya Bioregion of the Australian continent, home to the city of Adelaide, has undergone many changes throughout history as the continent itself has journeyed around the planet. It seems amazing that the theory of continental drift was first proposed and debated back in the late 19th and early 20th century. In fact, it wasn’t until the 1960s and 70s — just before the Ecological Crisis (EC) of the 1990s — that the concept of continental drift began to gain acceptance! (Nance & Speight, 1986 pp4–5).
Even now, some 150 years EC, there is no overriding consensus about continental drift. Estimates vary, but the following should provide a sense of how the shape of our terrestrial world came to be.
The Big Jigsaw Puzzle
Generally, it is accepted that about 200 million years ago, all of the continents were once a single giant land mass called Pangaea (‘all earth’ — Gaea or Gaia is the Greek name for the Earth Goddess).
This ‘supercontinent’ slowly began to break in half, essentially forming the northern and southern hemispheres. The new northern continent of Laurasia and the southern continent of Gondwana shaped the face of the earth around 150 million years ago.
These continents were separated by the Tethys Sea (Nance & Speight, 1986 p5). Eventually, the continents we recognise today — Australia, Antarctica, Africa, Asia the Americas and Europe — began to emerge about 50 million years ago (World Book, 1992 pp315–316).
The Wanderings of a Continent
The movements of the Australian continent resulted in an ever-changing climate, though this would have not been noticed by humans who, had they been around, would have slowly adapted to their environs over time.
About 480 million years ago, our travelling continent was positioned almost at right angles relative to its current position in the 22nd century. The western half of Australia was in the southern hemisphere, while the rest of the continent was in the northern hemisphere! At 280 million years ago, Australia was careering toward Antarctica, but this trend was reversed around 100 million years ago when the continent began to journey back toward the Equator (Cranby, 1993 pp10–11).
Today, Australia lies approximately between 10 degrees and 45 degrees south of the Equator (including Tasmania). In time, the continent will voyage elsewhere again.
The Big Chill
Ice Ages also affected the landscape of Australia and the Tandanya Bioregion. ‘Large granite boulders picked up by the ice as it moved over Encounter Bay were dropped some distance away when the ice melted…225 million years ago.’ (Nance & Speight, 1986 p8). These ‘glacial erratics’ can be found at Hallett Cove and on beaches north of Cape Jervis.
The last great Ice Age began around 40,000 years ago, causing the sea level to drop greatly as the water became ‘locked up’ in glaciers. At the height of this Ice Age, 18000 years ago, the sea level was 70 km south of 20th century Kangaroo Island, and the Gulf of St Vincent and Spencer Gulf were dry, shallow valleys . The ice began to melt around 6,000 years ago, with the sea returning to higher levels and bringing warmer and wetter weather with an increase in plant and animal life (Education Department of SA, 1989 p39).
History Lives In The Present
What has all this got to do with the urban ecology of Adelaide? Everything! This history explains the climate, the soils, the weather, the rainfall, the flora & fauna and the availability of resources in the Tandanya Bioregion.
An explanation of the ecology of a region helps to explain the activities and culture of the civilisations which occupy the area, especially city-making civilisations. But perhaps most importantly, it demonstrates that the characteristics of a bioregion or a continent are not ‘fixed’ or static, that they can and do change. There is even a theory that Ice Ages are the earth’s natural, cool state, with the current interglacial period merely a kind of ‘planetary fever’! (Lovelock, 1991 p148).
This brief examination of earth’s geological and geomorphological (geo = earth, morph = change, logy = study of) history helps to put the activities of human beings, whose numbers and technologies enabled the manipulation of the global environment by the late 20th century, into perspective.
Bioregional Resources
Interim Biogeographic Regionalisation for Australia
References
Cranby, Stephen (Geography Adviser) (1993) Oxford Australian Students’ Atlas. Oxford University Press, South Melbourne.
Education Department of South Australia (1989) The Kaurna: Aboriginal People of the Adelaide Plains. Education Dept of SA, Adelaide.
Lovelock, James (1991) Gaia: The Practical Science of Planetary Medicine. Allen & Unwin, North Sydney.
Nance, C & Speight, DL (1986) A Land Transformed: Environmental Change in South Australia. Longman Cheshire, Melbourne.
World Book (1992) World Book Encyclopedia. World Book Inc, Chicago, USA.
