In the beginning the depth of an archaeologist's research was limited by how far they could dig, but 20th century technology, such as carbon dating and ground penetrating radar, helped advance the field to new lows.
And now light detection and ranging scanning (lidar) technology has led to an exciting discovery in western Mexico- an ancient "lost" city with as many buildings as Manhattan, built by the Aztec's rivals the Purépecha:
“To think that this massive city existed in the heartland of Mexico for all this time and nobody knew it was there is kind of amazing,” said Chris Fisher, an archaeologist at Colorado State University who is presenting the latest findings from the study at the conference of the American Association for the Advancement of Science in Austin, Texas, this week.
While less well known than the Aztecs, the Purépecha were a major civilisation in central Mexico in the early 16th century, before Europeans arrived and wreaked havoc through war and disease. Purépecha cities included an imperial capital called Tzintzuntzan that lies on the edge of Lake Pátzcuaro in western Mexico, an area in which modern Purépecha communities still live.
Using lidar, researchers have found that the recently-discovered city, known as Angamuco, was more than double the size of Tzintzuntzan – although probably not as densely populated – extending over 26 km2 of ground that was covered by a lava flow thousands of years ago.
“That is a huge area with a lot of people and a lot of architectural foundations that are represented,” said Fisher. “If you do the maths, all of a sudden you are talking about 40,000 building foundations up there, which is [about] the same number of building foundations that are on the island of Manhattan.”
First found by researchers in 2007, archeologists initially attempted to explore Angamuco using a traditional “boots on the ground” approach, resulting in the discovery of about 1,500 architectural features over each square kilometre surveyed. But the team soon realised the rugged terrain meant it would take at least a decade to map the whole area.
Instead, since 2011 the lidar technique has been used to map a 35km2 area, revealing an astonishing array of features at high resolution, from pyramids and temples to road systems, garden areas for growing food and even ball courts.
So far more than 7,000 architectural features over a 4km2 area seen using lidar have been verified by the team on the ground, with excavations undertaken at seven locations to shed further light on the site.