The Pinnacles are accessed by the road from Arkaroola to Yudnamuntana, a sign leading to the nearby car park. An indicated walking track to the left leads from here to the foot of the main pinnacle. Basic, moderate to advanced rock climbing skills are needed to reach the summit, depending on the way you chose. A chimney crack to the west is fairly easy climbing, while still exposed at heights. Alternatively, a constant slope can be found on the east side.
In quiet times, you may see the yellow footed rock wallaby and wish to approach carefully with your camera. Other kangaroos may sit in the shade of the steep walls. Also enjoy the flora as you walk along from the car.
The prominent pinnacle in front of you is one larger of many pegmatite bodies. The granites, in essence, were the once deeply buried conduits of erupting explosive volcanoes.
By 460 million years B.C., explosive acidic volcanoes were widely active around the accurate outer edge of the secondary sediment trough from Kangaroo Island to Palmer, also northeastwards around to Anabama and southeastwards into western Victoria. About Arkaroola, white granite was introduced voluminously into the Freeling Heights region. Dyke-like offshoots penetrated south to include also the Armchair. Far above Mawson Valley, pipe-like pegmatite offshoots penetrated the surface to produce explosive acidic volcanoes. Stubbs of their eroded out pipes now form, beside others, The Pinnacles [1].
References:
[1] Reg C. Sprigg: "Arkaroola - Mount Painter in the Northern Flinders Ranges, S.A.: The Last Billion Years" (1984) Gillingham Printers Pty Ltd, Underdale, Australia, p 145.
Sister Cache
There exists a sister cache under equal name The Pinnacles (GC2J7JJ) in New South Wales, both hidden by The Arkaroo. If you liked the one here, please feel free to visit the other one and log the double visit in your entries, probably in adding a note to the first one.