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Excursion to glacial deposits of Flinders University Bedford Park Campus and western Sturt Gorge

Sunday 28 April, 2024

Leader: Dr Wolfgang Preiss
Contact: frances.williams@adelaide.edu.au



Ancient glacial deposits are extensively exposed on the Bedford Park Campus of Flinders University and adjacent Sturt Gorge. The excursion to examine these outcrops will involve car-pooling and a one-way walk totalling about three kilometres, with a drop-off point at Bedford Park and a pick-up point at Flagstaff Hill.

Excursion Summary

Sturt Gorge, 12 km south of the Adelaide CBD, is historically significant as the site where Prof. Walter Howchin first recognised evidence of ancient glaciation at the end of the 19th century. Howchin considered this glaciation to be of Cambrian age, along with all the rocks of the Mount Lofty Ranges, but later work demonstrated that most of these rocks, including those of glacial origin, underlie fossiliferous Cambrian strata and are Neoproterozoic. Currently available dating does not closely constrain the age of the onset of glaciation in Australia, except that it occurred later than about 730 Ma (million years ago). The deglacial phase is well dated at about 660 Ma and the glaciation was all over by about 650 Ma.

Flinders University, South Australia’s second university, was opened in 1966. It quickly expanded to include most faculties and Earth science disciplines figured strongly from the start – geology, marine geology, hydrogeology and meteorology. However, no account of the geology of its Bedford Park Campus has ever been published. 

The Bedford Park Campus occupies a commanding position on the escarpment of the Eden-Burnside Fault, overlooking Adelaide’s southern suburbs. The escarpment has many rock outcrops, some natural and others in cuttings associated with roads, buildings and carparks. The outcrops on the university grounds are of two Neoproterozoic formations, the Sturt Formation (formerly known as Sturt Tillite) and the Tapley Hill Formation, both of which contain a number of distinct rock types, as will be examined on the excursion. These formations record the Sturt glacial maximum and the subsequent post-glacial marine transgression respectively, but a record of the deglacial phase, represented in the Flinders Ranges by the Wilyerpa Formation, is missing in the Adelaide Hills.

The campus lies adjacent to the western part of the Sturt Gorge Recreation Park.
Whereas the eastern part of the park takes in mainly the lower part of the Sturt Formation and its basal contact with the underlying Belair Subgroup, the western half of the park and the university campus display the middle and upper parts of the Sturt Formation and the lower parts of the overlying Tapley Hill Formation.

After starting from our drop-off point on Bellevue Drive, Bedford Park, we will stroll across the Flinders University Campus, leading to a descent into Sturt Gorge, where we will make a bushland lunch stop. A gentle climb out of the gorge on its southern slopes will take us to a pick-up point on Broadmeadow Drive, at the corner of Vincent Boulevard, Flagstaff Hill. The walk follows well-marked walking trails past numerous outcrops of massive diamictite (a non-genetic term for unsorted sedimentary rocks containing a wide variety of pebbles and cobbles in a fine-grained matrix), clast-poor diamictite, siltstone, sandstone, greywacke (impure, mud-rich sandstone with sand-sized rock fragments), lime-cemented arkosic (containing more than 25% feldspar) grit and minor conglomerate within the Sturt Formation. Diamictite in the Sturt Formation contains glacially striated and facetted pebbles and cobbles and is associated with bedded fine-grained sediments containing pebbles dropped from melting icebergs (dropstones). On this evidence, it is interpreted to be of glacial origin, and can therefore be termed ‘tillite’.

The disconformably overlying Tapley Hill Formation commences with a basal ‘cap dolomite’ and very thinly laminated black shale of the Tindelpina Shale Member and grades up into thinly laminated siltstone. This important boundary is seen twice on the excursion – firstly at the Flinders University bus hub and again in the final ascent of the excursion out of Sturt Gorge. This last part of the walk appears to correspond to the site of a geological cross-section drawn in 1907 by Sir Edgeworth David and reproduced by Barry Cooper in 2010.

Many outcrops also show the effects of deformation due to the Delamerian Orogeny at ~500 Ma, most prominently the generally east-dipping cleavage. The trail also crosses a shear zone displacing the base of the Tapley Hill Formation.

There will be many opportunities to debate the environments of deposition of the glacial sediments, their age (only the deglacial phase is tightly controlled by geochronology), their relationship to local and global tectonics, and the merits and deficiencies of the currently popular ‘Snowball Earth’ hypothesis.


We will all meet at 9.30 a.m. at the pick-up point (corner of Broadmeadow Drive and Vincent Boulevard, Flagstaff Hill). This spot is accessed via Black Road and Glenalvon Drive, Flagstaff Hill. Black Road can be accessed via two ways, depending which direction you are coming from:
•    either via Darlington and Flagstaff Hill Road, turning left at the big roundabout
•    or Blackwood and Coromandel Valley, turning right about 2 km south of Coromandel Valley.
Be sure to turn LEFT at the junction of Glenalvon Drive and Vincent Boulevard and follow Vincent Boulevard to the junction with Broadmeadow Drive. Turn left at this junction and find a safe place to park on the roadside, We will then leave half the cars there and share rides to the drop-off point in the other half of the cars. These cars will drive back via Glenalvon Drive and turn left into Black Road. At the T-junction at the east end of Black Road, turn left into Main Road and drive via Coromandel Valley to Blackwood. At the Blackwood roundabout, turn left into Shepherds Hill Road. After 3 km turn left off Shepherds Hill Road onto Sargent Parade and immediately right onto Ridgehaven Drive. (If you miss the turn onto Sargent Parade, take the immediate next left onto Heathfield Road).  Follow Ridgehaven Drive (steep and windy!) to Sherwood Avenue, turn right and continue (going round a sharp bend) to the junction with Bellevue Drive. Turn left and park just north of the junction with Ridgehaven Drive. (The detour via Sherwood Avenue is necessary in order to end up on the permitted side of the road for parking.) The excursion commences at roadside outcrops on the west side of Bellevue Drive.

At the end of the excursion at about 4.00 p.m., drivers of the remaining cars will need to take passengers back to the drop-off point on Bellevue Drive before heading home.

Bring field equipment and your own picnic lunch and drinks as there is nowhere to purchase anything in the gorge. There is also no shelter after leaving the university campus, so be prepared for weather changes.

Toilets are available at the Flinders University campus before we descend into the gorge. After that it is bushes or boulders!

Registration is essential, either by signing the sheet at the April FGC meeting or by contacting Frances Williams:
(email frances.williams@adelaide.edu.au). 

Please indicate if you are able to take passengers. We need to have enough cars at the drop-off and pick-up points to transport all the participants both ways.