Continuing with Graham Hancock's work: America Before; The Key to Earth’s Lost Civilization...

...THE FIRST FOREIGN VISITOR TO mention the existence of megalithic circles in the Amazon was the Swiss zoologist Emílio Goeldi, who traveled up the Cunani River into what is now the northern part of the Brazilian state of Amapá, near its border with French Guiana, in the late nineteenth century.1 He makes no mention, however, of formations of huge granite blocks, obviously worked upon and moved into place by human beings, overlooking a stream called the Rego Grande.

In the 1920s Curt Nimuendajú, a German-Brazilian ethnologist, also visited megaliths in the region, but he likewise appears to have been unaware of the spectacular formations of Rego Grande. They were seen, however, and noted by Betty Meggers and her colleague Clifford Evans of the Smithsonian Institution in the 1950s 2 and now, at last, with the Smithsonian’s resources, came the opportunity for a thorough investigation of the mysterious site. Predictably, what we might call “the curse of Meggers” descended upon the Rego Grande stone circles. These great formations of megaliths shouldn’t have existed at all, according to her prejudices about the ancient Amazon, and were thus deemed unworthy of further excavation.3

Thereafter, lacking the Smithsonian’s seal of approval, the interesting problem of Rego Grande was quietly set aside and ignored by archaeology for the next 40 years while the site itself fell back into its former state of absolute obscurity and was in due course forgotten.

But climates of opinion in scholarship from time to time undergo radical shifts, and forgotten things sometimes cry out to be remembered. Thus, just as the geoglyphs of Acre were first identified back in the 1970s in an area where swaths of formerly dense rainforest were being cleared for use by the cattle industry, so it was with the Rego Grande stone circles. They were rediscovered in the 1990s by ranch foreman Lailson Camelo da Silva, who was clearing land for pasture. “I had no idea that I was discovering the Amazon’s own Stonehenge,” he later told a reporter. “It makes me wonder. What other secrets about our past are still hidden in Brazil’s jungles?”4
https://exploringrealhistory.blogspot.com/2020/09/part-6-america-before-key-to-earths.html