Outback Geography: The Physical Geography of Australia: Weathering

The continent of Australia contains many sings of weathering landscapes. A main process in which weathering takes place is called jointing. Joints are cracks in rocks which split the rock to allow further weathering processes to take place.

The picture captures numerous joints (cracks) in the rock, pointing to signs that this landscape has been physically weathered.
Photo Credit: https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgFFqmqQpXhg0BRCi59wnlNYUOKIlsXtyyt5980s-FxPhjlDt6WT6HEERmtLDIml8tdqmXvxlaFtE7S38ddVG_PhriLjzj2IKm1ma8cpgyzhME0dQQkbBIkUvp6V4pH_DVjfcBYQmQnJu6U/s400/dike-Wolf-Creek-zoom.jpg

Ayers Rock (also known as Uluru) is a large sandstone rock in central Australia. The rock is known to have very little jointing. The survival of the rock is due to the lack of scree slopes and soil allowing it to stretch over 5.8 miles today. Scree (talus) is the accumulation of broken rocks or sediment around the base of a rock.

A far look at Ayers Rock, showing the lack of joints and scree.

Photo Credit: http://britishfreedom.org/wp-content/uploads/2011/11/ayers-rock.jpg

Another form of physical weathering takes place with the introduction of salt. Salt, being able to hold water, can expand and contract rocks forming splits or joints. It can also form small or large holes in the rock called alveoli (small) or tafoni (large). To the right is a picture illustrating the examples of salt weathering.

Ayers rock displays both large scale tafoni on the bottom half of the rock to the right, and small scale alveoli in the center of the picture. The white hues of the rock are signs of salt weathering creating these cavernous structures.

Photo Credit: http://www.themikezone.co

Chemical weathering is another process that can decompose rocks and minerals. A common type of chemical weathering takes place through the process of dissolution. Dissolution created the Jenolan Caves of Australia illustrated in the picture below. Dissolution of limestone (most common) breaks down the chemicals in the rock to make carbonic acid. After this process they start to dissolve the limestone creating these large caves.