Sturt Gorge is flanked by rocks deposited during a worldwide glacial episode that occurred around 700 million years (Ma) ago. First recognised here in 1901 by Professor Walter Howchin, the glacial episode is known geologically as the Sturtian glaciation and the rock formation itself, the Sturt Tillite, is world famous.

This excursion will complement that led by Dr Wolfgang Preiss in 2024 in which we observed the termination of the Sturtian glaciation , starting from the fortunately preserved outcrop at Flinders University. The aim of this second excursion is to observe the start of the glaciation with evidence coming from another fortunately preserved outcrop in a roadcut beside Magpie Creek.

We will meet at 9.00 am at Gate 24, Broadmeadow Drive, Flagstaff Hill, in order to arrange a vehicle shuttle to Bushland Drive, Bellevue Heights, the start of the walk. While the walk will be down the valley, we’ll be travelling upwards in time, deep within the tillite. There are many good clean outcrops of tillite that not only demonstrate glacial features, but also the disruption caused by the Delamerian Orogeny of 500 million years ago. The glacial rock-types are not restricted to tillite but also include river-deposited sandstones, as well as a fine-grained silty unit. The latter, the siltstone marker bed, essentially divides the tillite into two, lower (older) Bulletin of the Field Geology Club of South Australia (Inc) Vol. 55 No. 2 Page 3 and upper (younger). The footpath continues westward along the Sturt River, still within the lower tillite, but with the siltstone marker bed on either side until it dips and disappears below the upper tillite, the official termination of the route. From here we will ascend from the gorge via the Parrianna Track to Broadmeadow Drive, Flagstaff Hill. We will then drive back to Bushland Drive (about 20 minutes) to retrieve the vehicles left at the start of the walk.

We aim to finish the excursion around 4 pm.

Please note that you need to be reasonably fit to participate in this excursion. The total length of the walk is somewhat over 4 km; this includes a steep descent into the Gorge at the start, and a steep ascent out at the end. Within the gorge itself the track is gently downhill but narrow, rough in places and there are 5 river crossings using stepping stones (though the water level will be low at this time of the year). There will be plenty of stops to enjoy the geology and scenery. You will need to carry food, plenty of water and all other requirements for the day, and toilet facilities will be bushes or rocks. If you attended the trip led by Dr. Wolfgang Preiss in 2024 conditions and level of difficulty will be much the same as that.

If you have not already registered for this excursion please sign the sheet at the March meeting or contact Frances Williams (contact details on the last page of this Bulletin). Detailed information, instructions and notes will be sent nearer the time to those who have registered. Colin Conor and Frances Williams