Wave Rock, Hayden, Australia

One aspect of Wave Rock rarely shown on photographs is the retaining wall about halfway up the rock. This follows the contours and allows rainwater to be collected in a storage dam. It was constructed in 1951 by the Public Works Department, and such walls are common on many similar rocks in the Wheatbelt.
Geology
Wave Rock is composed of granite. The total outcrop covers several hectares and is part of the Hyden Rock erosional remnant. The "wave" part of the rock is about 15 m (50 ft) high and around 110 m (350 ft) long. It should be pointed out that the 'wave' formation was formed 60 million years ago and the shape of the rock is not caused by a wave phenomenon, rather its rounded wave-like shape was formed by subsurface chemical weathering followed by removal of the soft weathered granite by fluvial erosion, thus the weathering occurred under ground level before it was exposed. The end result is an undercut base, leaving a round overhang.