Last updated: August 21, 2024
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How Were Petroglyphs, Pictographs, and Inscriptions Made?
Petroglyphs are carved into rock faces by striking a stone into the surface to peck out markings.
People used rock tools to make petroglyphs. The rocks were gathered from near the site.
- Sharp-edged chipped tools made fine lines.
- Blunt tools left thicker lines.
- Chipping or abrading a patinated surface -- called “desert varnish” -- exposed the lighter color beneath.
- Abrasion prepared a surface or filled in a shape. Rubbing a stone sideways against the rock surface created texture.
- Drilling using sharp objects punched small holes in rock.
These techniques created shapes, textures, and depth.
Pictographs are painted on rock faces. People made paints from pigments ground from minerals and added to a binder.
Gathering the ingredients for and making paints was part of the process for marking pictographs. People used calcium carbonate for white, hematite for red, yellow ochre for yellow, turquoise for blue, and charcoal for black. They mixed the minerals with plant or animal oils, saliva, eggs, blood, urine, grease or beeswax to help bind the pigment to the rock. The pigments were applied using tools such as sticks or brushes, or fingers and hands.
Graffiti consists of initials or marks, typically from the modern era. It may be carved or painted onto rock faces.
The NPS does preserve historic graffiti that is 50 years old or older. It is powerfully important that visitors today not leave their own graffiti. In fact, using paint on or carving into rock is against federal law. Be careful not to confuse modern tagging, spraying, or drawing with petroglyphs, pictographs, or inscriptions.
Think about carving or painting a mark on rock – it's not easy, or fast! Petroglyphs, pictographs, and inscriptions took time, planning, and teamwork to make.
Look closely for clues in the qualities of the rock face itself, the techniques chosen to create rock markings, and the styles or motifs. Consider if people constructed ladders, scaffolds or even a boat, to reach the site. Think about the relationship with the surrounding landscape and the relationship of the image to the sun, to other rock formations, and access points.
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