The first 6 images are reproductions and not the real thing. Petroglyphs were produced by etching. The ancient people who made them used rock tools made out of a harder rock than the sandstone upon which they were etching. The black substance that is on the rock walls upon which they etched is a type of lacquer that leaches from the sandstone during the natural weathering process over time. Pictographs were made from a paint that ancients produced from hematite. The iron in hematite is what makes the color red. I think it's amazing that so called 'primitive' people could produce a paint that has lasted for 10,000 years!