Ancient rock engravings resist the test of time thanks to the nature of the rocks on which they were created, such as sandstone or granite, which are hard and durable materials. Furthermore, most of these engravings are sheltered in natural cavities or under rock overhangs, protecting them from the weather and erosion.
The ancient mineral pigments used by our ancestors were primarily composed of very durable natural materials such as ochres, derived from clayey soils rich in iron oxides. These oxides provided particularly stable red, yellow, or brown colors against time, rain, or heat. Vegetable charcoal was common for obtaining lasting black shades, and calcium carbonate (chalk or ground bones) produced solid white tones. Since these minerals hardly degrade chemically, the colors on rock engravings have managed to survive thousands of years with minimal loss of their vibrancy or complete fading.
Natural structures like caves, rock shelters, or certain nooks sheltered from the sun and rain provide effective protection for ancient engravings. Without direct exposure to the elements, the drawings are better preserved, as the rock hardly wears away. Some pigments, initially fragile, can endure for thousands of years thanks to a stable and protected rock surface. Similarly, in these spaces, temperatures often remain constant, limiting cracks caused by sudden climate changes. These natural nooks significantly slow down the processes of erosion, allowing the traces left by our ancestors to peacefully endure through the centuries.
Ancient peoples primarily used hard stones, such as flint, obsidian, or quartz, to carve solid and durable patterns on rock. The principle was simple and effective: striking or scraping the surface with these sturdy tools to carve the stone without dulling too much. Some also employed the technique known as pecking: using a pointed stone struck repeatedly, they gradually created precise and resilient lines or patterns. The ancients favored repetitive and patient gestures, ultimately ensuring a carving capable of lasting thousands of years. Metal tools, like those made of bronze or iron, when available, were also used to achieve even deeper and more pronounced engravings. These simple yet sturdy techniques explain why today we can still admire these works that are thousands of years old.
Dry or arid climates particularly protect rock engravings because humidity generally promotes the degradation of materials. In desert environments, the lack of water limits the growth of mosses, lichens, or bacteria that could deteriorate the stone. In contrast, a very humid environment or one exposed to regular precipitation accelerates erosion and more quickly weakens the engravings. Locations benefiting from a natural shelter against the elements, such as a rock cavity or an overhanging wall, also provide good conditions by limiting rain, direct sunlight, drastic temperature variations, and corrosive winds. Finally, a stable climate with few extreme temperature variations allows the rock to remain in good condition for much longer.
Iron oxides, commonly used in prehistoric pigments, exhibit exceptional resistance to alteration, which partly explains the remarkable longevity of ancient paintings and engravings.
Direct exposure to sunlight and rain can quickly degrade modern works, but many rock engravings have survived thanks to their protected location within natural rock cavities or beneath rock overhangs.
By studying ancient engravings, experts can determine historical climate variations as well as the migrations and cultural interactions that have shaped the history of humanity.
The stone and bone tools used to create rock engravings were so sturdy and durable that the marks of the precise gestures made by ancient artists are still sometimes visible today, providing valuable insights into their techniques.
Although the direct dating of rock engravings is complex, archaeologists often use indirect methods, such as analyzing the pigments used or studying the geological and organic layers adjacent to the engravings.
Ancient mineral pigments, such as iron or manganese oxides, have excellent chemical stability against the wear of time. Due to their resilient composition, these pigments can endure for thousands of years.
The best protection involves controlling access to the sites, monitoring the environments around the engravings, and limiting direct human impact (tourism, vandalism). Sometimes, physical barriers, protective coatings, or special shelters are installed to ensure their preservation.
It depends on the locations: some sites are open to the public, often under supervision, to ensure their protection. Others, which are more sensitive, remain closed or are accessible only through organized visits in order to preserve the integrity of the engravings.
Hard rocks like granite, basalt, or sandstone are often favored because their high density and low porosity make them extremely resistant to natural erosion and weathering.
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