As deforestation clears away more and more of the Amazon Jungle, archaeologists are discovering some surprising things hidden beneath the thick green canopy. Researchers have found a number of ancient geometric shapes, known as geoglyphs, that are believed to have been carved into the earth more than 700 years ago by indigenous tribes living in the region.

According to this story from Treehugger.com, researchers are using Google Earth to examine recently cleared sections of the Amazon Rainforest. So far, they’ve been able to identify more than 300 geoglyphs, most of which had previously gone unseen due to being covered by the jungle and in some cases, the enormous size of the carvings. As of yet, scientists are unsure as to the purpose of the geoglyphs, as they are often completely undetectable from the ground and seem to serve little practical purpose.

To give you a sense of the scale of these geoglyphs, Archaeologists say that they are often as much as 12 meters wide and 4 deep, and can spread out over hundreds of meters in length. They were apparently constructed while the jungle was at the height of its growth, which makes their existence all the more puzzling and astounding.

While the researchers discovering these carvings continue to be amazed by what they find, it comes with a bit of sadness as well. These ancient constructs would remain hidden if it wasn’t for the massive deforestation that continues in the Amazon, a process that could have an irrevocable impact on the Earth’s environment.