The Sturt Gorge Recreation Park holds significant geological importance due to its recognition as an area of great geological significance. The park’s notable feature is the Sturt River, which has carved a narrow and deep gorge through the resilient glacial deposit known as Sturt Tillite. As early as 1901, geologists identified the rock strata in Sturt Gorge as having glacial origins. Notably, the Sturt Tillite formation stands out as the first area to provide concrete evidence of glaciation during the early stages of Earth’s geological history.
In a letter to the previous owner of the gorge, Sir Douglas Mawson, a renowned geologist and Antarctic explorer, expressed the locality’s exceptional scientific interest due to the presence of an ancient glacial deposit on the land. This deposit formed approximately 800 million years ago when a vast expanse of South Australia was submerged under the ocean. Massive masses of floating ice extended several hundred kilometers inland from the present coastline. Sturt Tillite is believed to have originated from glacial material deposited by the floating ice, consisting of stones of various sizes, boulders, and mudstones.
Overlying the Sturt Tillite is the Tapley Hill Formation, which includes slates deposited as sediments in deep lakes that covered the area around 700 million years ago. The oldest rocks in the park are siltstones and quartzites, found in small outcrops in the southeastern corner.
Regarding topography and drainage, Sturt Gorge Recreation Park is situated on the Eden Fault Block, forming an undulating plateau at an elevation of approximately 200 meters. The park’s slopes are generally steep, featuring extensive cliffs where the Sturt River has carved its narrow gorge through the resistant tillite strata.
The park’s relief varies, reaching a maximum of 135 meters, with elevations ranging from 50 meters where the Sturt River intersects the northern boundary of the park to a maximum of 180-185 meters in certain boundary areas and the Craigburn addition. Flat land is scarce within the park, mostly limited to small riverflats along the river and ridge-top areas in the Craigburn addition.
The Sturt River serves as the primary drainage line in the park, representing one of the major catchments in the western Mount Lofty Ranges. It drains a vast area extending eastwards, encompassing Belair, Crafers, Heathfield, and Cherry Gardens. The management of the park is influenced by the extensive catchment area, as water quality and the control of riverbed weed infestations depend significantly on events occurring upstream beyond the park boundaries.
Several minor tributaries of the Sturt River drain portions of the park, including Spring Creek, which is locally known as the largest tributary. It flows through the major valley known as Spring Gully in the western section of the park. Increased residential development in the vicinity has led to concentrated runoff due to stormwater drains, causing erosion issues in certain areas, such as stormwater outlets off The Boulevard and Broadmeadow Drive.
A significant and long-standing erosion gully exists in the cleared portion of the Craigburn addition. This gully, present in aerial photographs from as early as 1949, is likely much older and appears to have stopped extending further upslope due to lateral extension, but it continues to deepen.
Sturt Tillite…
Sturt Gorge holds substantial geological significance, especially after Howchin provided definitive evidence of the glacial origin of rock strata exposed in the gorge in 1901. This formation, known as Sturt Tillite, was the first to offer concrete evidence of glaciation during
the early stages of Earth’s geological history.
Sturt Tillite is a glacial deposit that formed approximately 800 million years ago when a large portion of South Australia was submerged under the ocean. Massive masses of floating ice extended several hundred kilometers inland from the present coastline, depositing glacial material on the land. Sturt Tillite consists of stones of various sizes, boulders, and mudstones, all of which were carried and deposited by the floating ice.
The Sturt Gorge Recreation Park showcases the unique geological features associated with Sturt Tillite. The park is situated on the Eden Fault Block, forming an undulating plateau with an elevation of around 200 meters. The slopes within the park are generally steep, and the Sturt River has carved a narrow gorge through the resistant tillite strata, creating impressive cliffs.
Above the Sturt Tillite, the Tapley Hill Formation can be found. This formation consists of slates that were deposited as sediments in deep lakes around 700 million years ago. In the southeastern corner of the park, you can find the oldest rocks, which include siltstones and quartzites.
In terms of topography and drainage, the park’s relief varies, with elevations ranging from 50 meters where the Sturt River intersects the northern boundary to a maximum of 180-185 meters in certain boundary areas and the Craigburn addition. The park has limited flat land, mostly found in small riverflats along the Sturt River and ridge-top areas in the Craigburn addition.
The Sturt River serves as the primary drainage line within the park, and it is one of the major catchments in the western Mount Lofty Ranges. The river drains a large area extending eastwards, including Belair, Crafers, Heathfield, and Cherry Gardens. The park’s management is influenced by the extensive catchment area, as water quality and the control of riverbed weed infestations depend significantly on events occurring upstream beyond the park boundaries.
Additionally, there are several minor tributaries of the Sturt River that drain portions of the park, including Spring Creek, also known as the largest tributary. Spring Creek flows through the major valley known as Spring Gully in the western section of the park. Increased residential development in the surrounding area has led to concentrated runoff through stormwater drains, causing erosion issues in certain areas.
One notable erosion feature is a long-standing gully in the cleared portion of the Craigburn addition. This gully, present in aerial photographs since at least 1949, is likely much older and appears to have ceased extending further upslope due to lateral extension. However, it continues to deepen over time.
Overall, the Sturt Gorge Recreation Park’s geology, including the Sturt Tillite formation, the topography shaped by the Sturt River, and the various drainage features, contributes to its significant geological importance and provides valuable insights into the Earth’s ancient glacial history.