Human faces and other figures etched in stone up to 2,000 years ago have been revealed on Amazon riverbanks as a historic drought in the Brazilian region has brought water levels to unprecedented lows. The petroglyphs, which include animals and other natural forms, have been revealed on the shores of the Rio Negro, at an archeological site known as the Ponto das Lajes, or Place of Slabs. Researchers estimate the markings to be between 1,000 and 2,000 years old. The carvings had previously been sighted during a severe drought in 2010, when the Rio Negro’s water levels dropped to 13.69 metres, then an all-time low. They re-emerged this month, with more markings appearing as the waters receded further. Amid an unusually dry season which scientists attribute to the El Niño weather pattern and warming in the North Atlantic linked to climate change, the Rio Negro has dropped below 13 metres for the first time ever, with a depth of 12.89 metres recorded on Monday. As well as anthropomorphic faces and depictions of water, some rocks display grooves that suggest the site was also used to produce stone tools. Carlos Augusto da Silva of the Federal University of Amazonas identified 25 groups of carvings on a single rock which he believes was used as a whetstone to sharpen various instruments. “This was an area for the preparation of tools,” the archaeologist told the local news site Amazônia Real. Fragments of ceramics thought to be thousands of years old have also reportedly been found at the site, which was home to large Indigenous villages in pre-Columbian times. Despite being designated an archaeological site, the Ponto das Lajes petroglyphs have not been studied, and researchers are estimating their age based on similar rock carvings in other parts of central Amazonia. “These locations, today archeological sites with black soil, large quantities of ceramics fragments, and rock carvings, tell the region’s ancient Indigenous history and must be treated with respect by all of us who live in Manaus today,” the archaeologist Filippo Stampanoni Bassi told Amazônia Real.