"No, No, Mesa Stay. Mesa Culled Jar Jar Binks. Mesa Your Humble Servant."
The landscape of the Big Desert Wilderness is the result of the following four geomorphic events.
1: A receding ocean shoreline during the early Pliocene (approximately 7 - 4.5 million years before present), leaving prominent north-south trending ridges on the upper surface of the Parilla Sand. The sand laterised to form sandstone during the monsoonal climate of the mid Pliocene, rendering them resistant to subsequent erosion. Remnants of these former foreshore dunes can be seen as rocky outcrops throughout the Big Desert.
2: Weathering of the north-south sandstone ridges during arid periods of the mid-Pleistocene (700 000 - 400 000 years before present), and the subsequent formation of east-west linear dunes. These Lowan Sands are typically infertile, with a low water-holding capacity.
3: Remobilisation of the east-west dunes at various stages during the late Pleistocene to early Holocene (400 000 to approximately 10 000 years before present) to form jumbled, irregular dunes. In Victoria, this dune type is restricted to the Big Desert and the southern Sunset Country. These dunes are mainly parabolic and sub-parabolic, with their main alignment to the east. They are inherently unstable and prone to remobilisation if disturbed.
4: Stabilisation of the dunes by vegetation (mostly mallee) during the past 7 000 years. As a result of these processes, the landscape of the Big Desert Wilderness comprises a large expanse of vegetated dunes, mostly with a relative relief of a few metres but with individual parabolic dunes 20-40 metres high. Occasional soaks and sandstone outcrops provide diversity in an otherwise geomorphologically uniform landscape.
At the listed coordinates you are standing on Mesa Rocks. You will also need to visit the secondary reference location to answers the following earthcache task.
-What is the height difference between the listed location and the reference location? Why do you think there is a difference?
-Compare the sandstone condition at the listed location and the reference location. What differences do you see? What effects do you think have occurred?
-Compare the sand condition of the Parilla sandstone with the Lowan sands. What difference do you see?
This earthcache is placed in a remote location. You will need to be self sufficient for a 30km walk in desert conditions. You will need adequate water, food and shelter. In accordance with the local park authorities you must walk to the location from the Murrayville-Nhill track. Do not attempt this walk on days of fire danger or excessive heat.
The Big Desert Wilderness is an outstanding semi-arid wilderness area and one of the least disturbed parts of Victoria. Its essentially undisturbed condition, large size and the occurrence of several significant species and communities make it highly valuable for nature conservation. It is an outstanding setting in which to experience solitude, inspiration and undertake self reliant recreation, notably walking.