'Pecked' engravings were made by hammering the surface of a rock so that the dark outer skin, or patina was removed and the lighter interior rock showed through. Because such accuracy was required to make these engravings, it seems probable that the artists used a stone punch and a hammer.

In contrast to pecked engravings, 'incised' engravings were made by cutting through the patina with another stone. The instrument could have been the same stone, because the patina through which the cut was made is softer than the interior, unweathered stone.

'Scratched' or 'scraped' engravings were made simply by scraping through the dark layer or patina. Generally they seem to be more recent than pecked or incised engravings.