Thursday, June 24, 2010

Aerial archaeology

There are many subdisciplines in the field of archaeology - including biblical archaeology, ethnoarchaeology, experimental archaeology, historical archaeology, and maritime archaeology, to name a few - but one of the most interesting is aerial archaeology, the study of archaeological remains by examining them from altitude. Imagine this:
"What's that? The field of ripe barley at two o'clock, two miles, near the L-shaped wood? Those patterns can't be natural ... too regular. Let's have a closer look ... There! A series of rectangles one with a circle inside. We'll have that. ... Opening window! Wing down a bit! ... more... more... that's great!" Grab the 35mm camera - photograph the target - reach behind you for the 70mm camera - wait - it's clearer from this angle, photograph it again. Log your position on the GPS, mark up the report form on the knee pad and go back to scanning, as you search for a new target.
That is a description of the photographic reconnaissance, which can be done in person from a plane or remotely from a kite. Fields of cereals, sugar beets, and peas are ideal for spotting cropmarks, patterns of differential growth in vegetation caused by variations in the subsoil - which may be due, for instance, to the presence of stone wall foundations. But such indicators of archaeological deposits may also be spotted in soil, frost, rainwater, and shadow patterns. Adding other technologies, like imaging radar, further enhance what can be seen by the naked eye, like the outlines of an ancient city in Tel al-Daaba, Egypt. Many scientists are making use of the satellite images from Google Earth to identify geoglyphs, such as those revealed when the Amazon rainforest is clearcut (click on images for more information). Some also use Google Earth to document the looting of ancient sites and lobby for their protection. But Google Earth is also credited with facilitating armchair archaeology, which makes for some surprising headlines in the weird news, as when L.A. musician Nathan Smith found indicators of a Spanish ship that ran aground in Texas in 1822 - carrying gold and silver worth a possible $3 billion.

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