Deep time

Geological and climatic underpinnings

There has been a river draining and fashioning the area we know as the Hunter Valley for, in very round terms, at least 50 million years. The land of the region took shape 300 million years ago during the carboniferous period, volcanic extrusions and sedimentation dominating its formation. The sediments, laid down in the Tasman Geosyncline, were raised above sea level. Much faulting and folding took place.

Later, during the Permian period about 250 million years ago, the Newcastle coal measures were laid down. A rupture in the earth’s surface then threw up the Great Dividing Range which was drained to east and west by streams. Further volcanic activity occurred, especially in what is now known as the Mt Royal Range. Later, volcanic outcrops appeared in the Pokolbin and Paterson areas.

Geological section from the Illawarra to New England

(Helen Russell)

Recognisable floodplains formed. Over a long period of time the sea level rose during interglacial periods and fell when the ice ages locked up water as ice in the polar regions and the world’s mountains. At one stage, more than 100,000 years ago when sea level was 120 metres lower than it now is, the coastline was about 30 kilometres east of its current location. The ancient Hunter River changed its course frequently, especially in the lower valley. At times, it flowed to Port Stephens.

By 6500 years ago the sea was a few metres higher than currently and beaches formed at the site of today’s Largs. For the past 5000 years, sea level has approximated its current level with slight rises over the past century due to global warming and the partial melting of the polar ice sheets.

A relatively warm climate since the last ice age ended 12,000 years ago saw the modern eucalypt and cedar forest assemblages evolve. On the floodplain the rainforest was thickly luxuriant, merging into open eucalypt-dominated woodland on the valley sides.

Over the millennia, floods deposited the silts and sands that are in places more than 30 metres thick on the valley floor. The river’s course changed frequently: in relatively recent geological time it flowed down what is now the Oakhampton floodway and through the areas of present-day Louth Park and the lower portion of East Maitland. Howes Lagoon was for a time a reach of the river.

Geological map and timescale

From Geology of the Lower Hunter Valley, New South Wales (pamphlet), NSW Trade and Investment, Resources and Energy, 2014.

The human impact

Into this evolving environment of forest, floodplain and the hilly perimeters of the Hunter Valley came human beings. Given that Aborigines are believed to have occupied northern Australia 65,000 years ago and reached Tasmania more than 40,000 years back, it can be inferred that the first humans might have lived in the area of today’s Maitland about 50,000 years ago. That figure implies human occupation of the area for perhaps a tenth of one per cent of the life of the river.

At some stage these first human occupants, with others who followed, evolved into the Wonnarua, Geawegel, Worimi, Awabakal, Wiradjuri and Kamilaroi peoples who occupied different parts of the valley. They lived semi-nomadic lifestyles but like all human groups they modified the environments in which they lived. Considerable vegetation change occurred, firestick farming promoting grasses especially away from the floodplains. More open woodlands developed on the hillsides, while the floodplains (where Aboriginal people tended not to make their habitations) remained thickly forested.

Europeans arrived only just over 200 years ago, an eyeblink in terms of human occupation and even less of a fraction of the geological history of the area. Quickly, widespread vegetation alteration and dramatic changes to the regime of the river occurred. Magnificent assemblages of cedar, rosewood, fig and other tree species disappeared from the floodplains and the extensive wetlands were drained to make way for a farming economy. The river’s channel became straighter, wider and shallower and its gradient steeper.

What we see now in the Maitland area is nothing like what existed two centuries ago, and even less like what was on show many thousands or millions of years back.

References

Keys, Chas ’Our past: step back in time . . . let’s say, 100,000 years’, Maitland Mercury, 2 March 2020.

Nashar, Beryl, The Geology of the Hunter Valley, Jacaranda, Brisbane, 1964.

Miller, James, Koori, a Will to Win: the heroic resistance, struggle and triumph of Black Australia, Angus & Robertson, Sydney, 1985.