Wilpena Pound - Geomorphology

Geomorphology

The area is part of the Adelaide Geosyncline. Despite early amateur theories that it was some kind of ancient volcano, the actual Pound is sedimentary rock in the form of a large syncline, with the fold axis running NNW-SSE through Edeowie Gorge at the northern end and Rawnsley's Bluff at the southern. A corresponding anticline is located in the adjacent Moralana Gorge, with the Elder Range on the downturned western limb. The area has given its name to the Wilpena Group of sedimentary rocks making up the younger sediments of the geosyncline, and names of further subdivisions also originate from the area: particularly the Pound Subgroup, made up of Rawnsley Quartzite and Bonney Sandstone. which were laid down during the Ediacaran Period.

Although from the outside the Pound appears as a single range of mountains, it is actually two: one on the western edge, and one on the eastern, joined by the long Rawnsley's Bluff at the south. A gorge called Wilpena Gap has been cut in the eastern range, and most of the inside of the Pound drains into Wilpena Creek which exits through the Gap. A small part of the high northern slopes of the Pound drains into Edeowie Creek, which drains in time of flood over steep cliffs and waterfalls in Edeowie Gorge to the north.

The highest peak in the Pound, also the highest of the Flinders Ranges, is St Mary Peak (1170m), on the north-eastern side. To the south of the Gap on the eastern side, the highest peak is Point Bonney (1133m). On the north-western side of the Pound, the highest point is Pompey's Pillar (1165m), and Rawnsley's Bluff (950m) at the southern end is the other major summit.

The wall of mountains almost completely encircles the gently-sloping interior of the Pound, with the only breaks being the gorge at Wilpena Gap and a high saddle in the south-western range over which the Heysen Trail passes. This latter saddle is called Bridle Gap, supposedly because it's the only place other than the gorge where a skilled horseman might ride into the Pound. The interior of the Pound does not rise to a height at the northern edge, but instead simply drops off very steeply to the plain below in a series of steep gullies.