(ORDO NEWS) — New details of our past are surfacing, hiding in the back alleys of the world, as we improve our methods of finding them. Most commendable is the reconstruction of human evolution since our African origin about 300,000 years ago by analyzing our living and fossil DNA.
Full of the ghosts of African and Eurasian populations of the deep past, they were only resurrected by the ability of science to penetrate the world of minute details by studying biomolecules.
Now digital analysis of the rock surface reveals how other ghosts of the deep past – this time from nearly 2,000 years ago in North America – have been brought to light.
In the journal Antiquity, Professor Jan Simek of the University of Tennessee and colleagues published images of giant glyphs carved into the mud surface of a low cave ceiling in Alabama.
These motifs depicting human forms and animals are among the largest known cave paintings found in North America and may represent the spirits of the underworld.
In the first image below, a design of a diamond rattlesnake, an animal sacred to the natives of the Southeastern United States, stretches nearly 3 meters in length. The next one below shows a human figure just over 1.8 meters long.
As for the dating of the finds, the ancient people rejuvenated the lamp in the cave (a burning torch made of American bamboo) by leaning it against the wall of the cave.
After that, a trace remained, which the researchers were able to radiocarbon date to 133-433 AD. This was also consistent with the age of the pottery fragments left by the ancient artists in the cave.
The problem is to see the pictures. The ceiling height of the cave is only 60 centimeters, which makes it impossible to step back to view the large images.
They have only been discovered using a technique called photogrammetry, in which thousands of overlapping photographs of an object or place are taken from different angles and digitally combined into 3D.
Photogrammetry is a low cost technique increasingly used in archeology to record artifacts, buildings, landscapes, and caves. This allowed Prof. Simek’s team to “lower” the floor of the cave by 4 meters, allowing for the first time to see all the motifs.
Ancient art elsewhere
Rock paintings are found on almost every continent, with the earliest being at least 64,000 years old. It is likely that we know only a small percentage of cave paintings created in the past.
Pigments can fade and disappear, fine engravings can fade away, and cave walls can crumble or crust with carbonate deposits or dirt. Assuming that more works of art still survive, then there is a chance that we will never see them if we do not invest in research and new technologies.
Rock paintings in the dark zone of caves outside of natural light at cave mouths were only discovered in North America in 1979, more than a century after they were discovered in Europe (at Altamira in northern Spain). About 500 European caves are known to contain cave paintings from the Pleistocene era between 2.6 million and 11,700 years ago.
One example critical to our study only came to light through digital image manipulation we did. Below is a stencil of a hand in the Maltravieso Cave (Extremadura, western Spain), which was not immediately noticed when we searched the cave for suitable specimens to date its art.
The stencil was shaded with calcium carbonate deposits. We photographed the site and then used digital image enhancement software which brought out the hand stencil very clearly (bottom right).
Until it reappeared on our computer screen, this 64,000-year-old hand-stencil remained undetected despite 70 years of intensive exploration of the cave.
Light engravings, a very common Pleistocene technique, are notoriously difficult to see. Parts of them can be found when shining at an oblique angle, which we call “raking light”.
But using a technique known as reflection transform imaging (RTI), which is similar to photogrammetry, 3D models can be illuminated from any angle. This allows for much more complete and complex images.
It’s not easy to show this in a couple of shots, but hopefully the two shots below of an engraved bison in El Castillo Cave in northern Spain give an idea.
Future archaeological searches for rock art are likely to benefit from recent developments in airport security.
Full-body scanners use far infrared light that safely penetrates clothing to detect hidden weapons or contraband, and similar methods have been used to “see through” layers of prehistoric wall plaster to see paintings underneath.
When these scanners become small and cheap enough to take into caves, who knows what other ghosts will show up? Conversation
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