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. Beyond archaeology, LiDAR researchers at the National Science Foundation are looking to develop the technology for mapping disasters using drones, for military spying and for tracking erosion under rivers and shallow parts of the ocean.
LiDAR for archaeology
Before LiDAR improved enough for their work, archaeologists discovered ruins the old-fashioned way — by hacking through forests using machetes. LiDAR is faster and cheaper. It’s been gaining ground since 2009, when a U.S. archaeology team working on Mayan ruins first used the technology to peer beneath 80 square miles (207 square kilometers) of forest canopy in Belize. After four days of laser scanning, team members discovered buildings and agricultural fields they hadn’t found in 25 years of study. The team was supported by the then-newly-created National Science Foundation organization for LiDAR science, the National Center for Airborne Laser Mapping. [10 Modern Tools for Indiana Jones]
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.