Terrapina Gorge + Tors

I mentioned in the earlier maps and territories post that on Day 8 we’d made our way to a camp near Terrapinna Gorge in the north east of the Flinders Ranges, and that we had an afternoon to explore both the gorge and the Terrapinna Tors. By this stage I was beginning to develop a vague sense of the geography– ie., Hamilton Creek flowed north east to Lake Callabonna and that we were on the southern edge of the arid interior.

What I didn’t I know was the geological history of the arid zone: ie., the historical past of the Pleistocene (2,580,000 to 11,700 years ago,) and the latter Holocene-— the time since the end of the last major glacial epoch, or “ice age around 11, 600 years ago. Nor did I know the history of the different deserts, that of the desert societies prior to colonisation, or how the various desert people were subsequently drawn into various missions and government settlements.

The map I had of this territory was the white settler-colonial one one in which Lake Callabonna was seen to be part of an arc that included Lake Blanche and Lake Gregory — a chain of large salt lakes. The map was based on E.J. Eyre’s 1840 expedition to northern South Australia, in which Eyre following the Flinders Ranges found his route blocked to the west, north and east by a chain of large salt lakes. Eyre thought this chain formed a single large ‘horseshoe lake’. He suggested that it was an old arm of the sea. This was the dead heart of settler Australia–a part of the ‘country that was once covered with salt water’; a territory that Charles Sturt understood to be a great inland sea.  

Terrapinna Gorge walls

In the afternoon of day 8 walking I wandered into Terrapina Gorge on my own as the rest of the group had decided to walk along the Terrapinna Tors trails, rather than entering the gorge. As I slowly made my way upstream, the stranded logs in the trees gave me a sense that a lot of flood water would have flowed through Hamilton creek when the northern monsoons reached the northern Flinders Ranges. As I walked along the rocky walls and sculptured basins I realized that many of Australia’s meandering ephemeral rivers drain inland, that they often end in ephemeral salt lakes (eg., the Lake Eyre drainage basin) and that many of the features of the internal drainage pattern have a very long history.

I wondered how was this gorge part of Australia’s geological past, its deep time of settlement and it being the home for the oldest continuing cultures in human history? From memory the last glacial period was at its most intense about 20 000 years ago, and by around 11,700 years ago the ice had retreated, the sea level had risen, and the land bridges to New Guinea and Tasmania (which had formed the single continent of Sahul) began disappearing under the rising sea. Around 6000 years ago Australia became an island continent. If the First Nation’s people had been in Australia for 65,000 years, then they would have lived through the last ice age and the subsequent dry periods.

walking in the Blue Mine Creek bed

At the end of the first day  of walking we camped at a wonderful campsite close to Blue Mine Gap on the north western edge of the Gammon Ranges. We  were  walking in there of  Sir Douglas Mawson’s  1906  explorations into the geology  of the northern Flinders Ranges.  In the 1920s  and 1930s Mawson amongst others concentrated his research and fieldwork  around the  mineralization the northern Flinders Ranges, eruptions of  the pre-Cambrian glaciation throughout the Flinders Ranges,   the Cambrian strata of the Flinders Range,  and the identification of uranium  at Mt Painter Inlier,  which is about 100 kilometres north east of Leigh Creek and south of the Mawson Plateau.    South Australia is one of the world’s focal points for the study of the late pre-Cambrian era and glaciation.

After lunch on the first day we crossed  a  creek bed. The camels were playing up a bit,  and this gave me  5-10 minutes or so  to do some photography  in and around the creek bed. Surprisingly, the  light was still soft due to the continuing cloud cover,  and the malaleucas in the  creek made a welcome change to the bareness and environmental degradation of the stony hills with the loss of endangered plants and animals from  the  history of extensive  pastoralism since the European occupation of the land.

malaleuca, creek bed

We had  left the Umberatana Station track to  walk in,  and along,  the Blue Mine Creek on the way to the campsite for the night.  It was dawning on me that there was a history of  extensive mining in  the region for copper in the 19th century,   and that the  systematic regional mapping of the northern Flinders Ranges  after 1945 centred around finding coal, petroleum and uranium.  Mining was  just as crucial as pastoralism in terms of land use.   Increasingly it is now eco-tourism that provides  the income and employment in the region.    Continue reading