Underneath the thick, virgin rainforest cover in the Mosquitia region of Honduras, archaeologists have discovered ruins they think may be the lost city of Ciudad Blanca.
Legends say the "White City" is full of gold, which is why conquistador Hernando Cortes was among the first Ciudad Blanca seekers in the 1500s. But the method the modern researchers used was a little different from previous explorers' techniques. The modern-day researchers flew over the area in a small plane and shot billions of laser pulses at the ground, creating a 3D digital map of the topology underneath the trees.
This is one of the first times this technique, called light detection and ranging (LiDAR), has been used to map ancient ruins.
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Airborne LiDAR works by sending more than 100,000 short laser pulses to the ground every second while a plane flies over the area of interest. The laser light hits the ground, then returns to the aircraft. The time it takes for the light to make the back-and-forth trip tells researchers the altitude of points on the ground.
The technology is able to detect height differences of less than 4 inches (10 centimeters) and maps to GPS coordinates within 4 to 8 inches (10 to 20 centimeters). "It's within a step, in many cases," said Bill Carter, University of Houston engineer who develops LiDAR systems for the National Science Foundation.
The Belize archaeology work and the new Honduras findings both used the National Center for Airborne Laser Mapping's LiDAR system. There was one major difference between the two projects, however. At the Belize site, researchers thought it was likely there would be new ruins there. They used the LiDAR to scan regions surrounding structures they had already uncovered. On the other hand, in the new study in Honduras, researchers were running on just a hunch — and plenty of private funding.