New details of our past are coming to light as we refine our techniques to find them. The reconstruction of the evolution of humanity since our African origins around 300,000 years ago is most appreciated.
Science has been able to reach into the world of the minuscule by studying biomolecules, and these have been resurrected.
Digital analysis of rock surfaces shows how other ghosts of the deep past have been brought into the light.
Professor Jan Simek of the University of Tennessee and colleagues have published images of giant glyph carved into the mud of a cave in Alabama.
Some of the largest known cave images found in North America are depictions of human forms and animals.
A drawing of a diamondback rattlesnake, an animal sacred to indigenous people in the south-eastern US, is almost 3 meters long in the first image below. A human figure is just over 1.8 meters in length.
Photographs by S. Alvarez and illustrations by J. Simek.
The Serpent figure has a round head and diamond-shaped body markings. There is a natural fissure in the ceiling limestone.
The ancient people rejuvenated a light in the cave by stubbing it against the wall. The researchers were able to date it to 133-433CE. The age of the pottery fragments left in the cave was also in accord with this.
Photographs by S. Alvarez and illustrations by J. Simek.
The petroglyph of a human figure is 1.81 meters tall.
There is a problem with seeing the paintings. The cave ceiling is only 60 centimeters high, making it hard to see large images. They were revealed through a technique called photogrammetry, in which thousands of photographs of an object or place are taken from different angles and combined in 3D.
Archaeology is increasingly using photogrammetry to record artifacts, buildings, landscapes, and caves. It allowed Professor Simek's team to get to the lower part of the cave floor, which was enough for the complete motifs to be seen for the first time.
The earliest rock art is at least 64,000 years old. We probably don't know much about the rock art created in the past.
Thin engravings can erode to nothing, and cave walls can be covered by mud or carbonate deposits. Unless we invest in research and new technologies, we may never see more art.
Rock art in the dark zone of caves beyond the natural light in cave mouths was only discovered in North America in 1979. Between 2.6 million and 11,700 years ago, rock art was found in 500 European caves.
One example critical to our own research only came to light through digital manipulation of images that we took. When we were searching the cave for suitable samples to date its art, the hand stencil in the cave was not immediately apparent.
The calcium carbonate deposits obscured the stencil. Digital image enhancement software revealed the hand stencil very clearly after we photographed the area.
The author is provided.
Despite 70 years of study in the cave, this 64,000-year-old hand stencil remained undiscovered until it reappeared on our computer screen.
Light engravings are difficult to see. We refer to it as light raking light because parts of it may come to light using light shone at an oblique angle.
3D models can be illuminated from any angle with the use ofRTI. These can show more complete and complex images.
It is not easy to show this in a couple of stills, but hopefully the two shots below of an engraved bison in a cave in El Castillo give a flavor.
The author is provided.
There is a digital photograph of the head of an engraved bison from El Castillo Cave, Spain.
Recent developments in airport security are likely to benefit future archaeological searches.
Full body scans use far red frequencies to penetrate clothing to reveal concealed weapons or contraband, and similar techniques have been used to see through layers of prehistoric wall plaster to paintings underneath.
Who knows what more ghosts will come to light when the scans become small and cheap?
Professors of Archaeology at Durham University and the University ofSouthampton are Paul and Alistair.
This article is free to use under a Creative Commons license. The original article is worth a read.
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