Lidar archaeology shines a light on hidden sites

If you think archaeologists spend all the time with trowel in hand in a muddy ditch then its time to think again. More and more are using sophisticated aircraft-mounted lasers, and it is opening up a new age of discovery.

For the best part of 25 years, archaeologists Arlen and Diane Chase slogged through the thick undergrowth in the west of Belize in search of an ancient city whose details had been lost to the passage of time and the decay of the jungle.

The going was tough, often requiring a machete to clear a path through the dense vines and creepers that blocked their way. Over time, their perseverance paid off as their hand-drawn maps began to reveal long-forgotten parts of the massive Mayan city of Caracol.

But the more the pair found, the more they realized the extent of what remained uncovered. It would take several lifetimes, they figured, to reveal the true extent of Caracol.

Then, in 2008, they got talking to a biologist colleague at the University of Central Florida where they worked. For years, he had been using airborne laser sensors known as Lidar (Light Detection And Ranging) to map and study forests and other vegetation. He suggested they give it a go.

So, in 2009, the pair packed away their machetes and hiking boots and took to the air in a twin-engine plane equipped with the technology. For four days they skimmed backwards and forwards over the tree-tops firing pulses of laser light at the ground below. A few weeks later, back at their lab in Florida, the pair got their first look at the results.

I was completely astounded, says Arlen Chase. We had not expected the clarity that we saw in the imagery.

I am pretty sure we uttered some expletives, Diane adds politely.

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