The Holocene Wet Phase, as it is called, fluctuated greatly between humid and dry periods and then reverted to a more consistent arid condition around 3800 BCE, as the rain belt retreated southward (Parker et al. The oldest known petroglyphs in Saudi Arabia are believed to date to the Neolithic period or Early Arabian Pastoral, which appears to coincide with at least part of the Holocene Wet Phase.
These images are typically carved or pecked deeply into the rock surface.
This is not typical of the rock art in Saudi Arabia, however, which tends to be exposed and lacking any settlement or camp next to the cliff face.
A palimpsest of animals from different ages at Shuwaymis: Faint images of Neolithic aurochsen (wild cattle), more recent camels and cavalryman, still younger men with exaggerated hands.
The hunter is usually aided by a pack of hunting dogs.
Although these people were part-time pastoralists with herds of sheep and goats, the art suggests that hunting played an important role in their subsistence.
Clues to relative dating include: the manufacturing technique used; the patina covering the art; the layering of figures on top of each other; the style of human forms; and the particular animal species, types of artifacts and subject matter shown.
Many species, such as mammoth and woolly rhinoceros thrived in Eurasia and the mammoth, mastodon, camel and giant sloth lived in North America.
The uniformly light color of the sandstone surfaces explains why the Neolithic artists had to incise or peck the images deeply into the rock: so that sunlight raking across them would cast shadows demarcating the outlines of the figures.
The most common Neolithic scenes are of hunter-herders with bows and arrows and throwing sticks, which are similar to a boomerang.
In this case, a rock art panel may be judged to be younger, older or basically contemporaneous with another petroglyph, a site, an artifact, or other evidence of known antiquity.
Relative dating, although somewhat less satisfying than absolute dating in terms of precision, is considerably more successful for petroglyphs.