State Circle Cutting, State Ccl, Canberra, ACT, Australia.
S 35° 18.290 E 149° 07.670
55H E 693460 N 6091074
This road cutting is a very significant site for the interpretation of local geology in that the unconformity between the Camp Hill sandstone and the State Circle shale marks the Quidongan orogeny in the Canberra area.
Waymark Code: WMVKJ3
Location: Australian Capital Territory, Australia
Date Posted: 04/29/2017
Views: 5
The State Circle Cutting is located immediately adjacent to traffic lanes in State Circle at Capital Hill between Commonwealth Avenue and Kings Avenue. The road cutting is approximately 320 metres in length. The exposure clearly shows the unconformable contact between the older State Circle Shale, and the younger Camp Hill Sandstone. A number of faults are present in the cutting, and some minor folds can also be seen. The gently folded Camp Hill Sandstone overlies the State Circle Shale, which is slumped and contorted.
Other geological features at the site include sandstone rafts, ripple marks and a pallid zone, all of which are important indicators of the varied environments that existed in the region during the Ordovician (approx. 460 - 440 million years ago) and Silurian (approx. 440 – 420 million years ago) geological periods. Structural features, such as folds and faults, point to the nature of the deformation of these rocks. 430 million years ago a large deep sea covered the Canberra area. Fine grained, silty sediments were deposited in deep water. When compacted they became the rocks of the State Circle Shale. An older sequence of sandstones broke up on an unstable slope and slumped down to the seafloor as large blocks. These blocks can be seen today in the roadcut as pink coloured sandstone rafts surrounded by the lighter brown, finer grained rocks of the State Circle Shale. 425 million years ago the rocks of the State Circle Shale became strongly folded by forces acting within the earth and were uplifted above sea level.
Source: Australian Heritage Database.
More information is given in the Earthcache notes: State Circle GC11BNE see here: (
visit link)
*** Another interesting Earthcache we enjoyed doing on our trip through Canberra, no kangaroos were spotted at this particular place, however we did have a memorable close encounter with several kangaroos that were guarding a geocache site in bushland beyond a Canberra housing suburb, and they just sat quietly watching us sign the logbook and allowed us to take their photos. More special moments we won't forget.***
Location: The exposed rock face on the northern side of State Circle between Commonwealth Avenue and Kings Avenue, Parkes. Canberra.
Commonwealth Heritage List
Class Natural
Legal Status Listed place (03/06/2005)
Place ID 105733
Place File No 8/01/000/0041
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