There are two major types of Rock Art - Pictographs and Petroglyphs
Pictographs are "Rock Paintings" (from the Latin pingere, to tattoo or paint) The "paints" commonly used are mineral ones, hematite (naturally red) and limonite (naturally yellow), which could be mixed to form other shades. Frequently containing iron-oxide, these paints were often baked, powdered and then mixed with water and a binding agent (animal fats, blood, egg or oil) to make them better stick and also to protect the pigment. They were applied to the rock's surface by hand and by brushes made from leaves. Click here to see a pictograph
Petroglyphs are made by carving, scraping, incising, grinding abrading or pecking stone walls or rocks. In other words, they are made using "direct" action (hitting the surface of the rock directly) and "indirect" action (such as hitting a such as a stone chisel with a stone hammer). The latter method makes better defined petroglyphs.
In many cases the rock is basalt which is naturally a light-grey colour or reddish sandstone. Over time, bacteria grow on the rock, and leave behind a sticky substance to which minerals, mostly manganese oxides and iron, stick forming a dark coloured patina which is called "desert varnish" or "rock varnish". It is this varnish which is removed to expose the original colour.
Pictographs can be dated using
Petroglyphs are cannot be dated using Radio Carbon Dating, as they contain no animal or plant remains.
Petroglyphs and Pictographs which look like
We have a responsibility to ensure the preservation of these sites for future generations. Touching rock art deposits oil from your hand, and abrades the surface. Apart from causing cumulative damage, it makes dating more difficult. Fortunately, vandalism of these sites is illegal and carries crippling fines and prison sentences. (Unfortunately, it is not yet punished by compulsory distribution of your body parts for medical research.)
What is Rock Art ?