In the late nineteenth century, the Swiss zoologist Emílio Goeldi, undertook an expedition up the Cunani River and found large stone blocks that seemed to point at the sky on lands that are in the current north of Amapá, an area that is the subject of litigation between Brazil and France. Over the first six decades of the last century, some renowned researchers, such as Curt Nimuendajú, a German, in the 1920’s and Betty Meggers and Clifford Evans, both of them Americans, at the end of the 1950’s, also saw these human constructions with their granite blocks at some archaeological sites. A small amount of pottery associated with the locations of the megaliths, as the large stone structures arranged or constructed by human hands are called, was retrieved and the interpretation was that just a small population of some pre-Colombian people must have made their dwelling place in that almost lost part of the Amazon. The sites must have been used basically for ceremonial purposes and after this the region became half-forgotten by science.
Until in 2005 a couple of young archaeologists from the state of Rio Grande do Sul, Mariana Petry Cabral and João Darcy de Moura Saldanha, left the south, moved to the capital of Amapá and started dedicating themselves to studying some 200 prehistoric sites in the state, of which some 30 have megaliths. Although there are still many gaps in the knowledge about the ancient culture that carved and arranged the blocks of granite, as much as 2.5 meters tall and weighing 4 tons, the two researchers produced a series of new data on the context in which these structures were erected. For the first time the important site of Rego Grande, which has attractive vertical stones, located in Calçoene, a municipality some 460 km north of Macapá, was the target of carbon 14 dating, one of the most reliable methods. “We managed to carry out three date checks on fragments of charcoal found within funeral wells in Rego Grande,” says Mariana, who works with Saldanha at the Institute of Scientific and Technological Research at the State of Amapá (Iepa). The place was inhabited around one thousand years ago, information that confirms the scientists’ initial estimates. A further ten sites in Amapá, three of them with megaliths, were also dated and all seem to have been occupied between seven hundred and a thousand years ago.
It is relatively common for pre-historic sites with megaliths to show evidence as having been used as places for the observation of some astronomical phenomenon. This is one of the functions commonly attributed to the famous stone circle of Stonehenge, erected 4.5 thousand years ago in Southern England. Is Rego Grande an Amazonian Stonehenge? Evidence supports this interpretation. Over the last few years archaeologists have carried out systematic measurements, always on December 21 or 22, which marks the winter solstice (Calçoene is north of the equator), and have found that a slim monolith appears to be aligned with the sun’s path throughout this day. When the sun rises it is at the top of the rock and as the hours pass it descends until it sets at the base of the rock. “At this time of the year the solstice marks the start of the rainy period in the Amazon,” comments Saldanha. “The Indians must have known this.” Two other blocks of granite, including one with a hole made by human hands, also occupy positions that are apparently associated with the movement of the Sun on this date. As the stones and inclined blocks of Rego Grande have strong foundations, also made of stones, the archaeologists believe that the angle of the megaliths was carefully considered by those who conceived them and that it is not the result of natural wear suffered by the pieces of granite on the site.
An expert on megaliths, particularly on those from the Alentejo, Portuguese archaeologist Manoel Calado, from the University of Lisbon, agrees with the hypothesis that the leaning stones of Rego Grande may have been arranged in this way to mark the observation on the line of the horizon of simple astronomical events of a cyclical nature, like the passage of the Sun on the solstice. “I’m sure (of this),” says Calado, who has already been to Amapá to become acquainted with the lithic structures on this site, but is not part of the Brazilian research group. “This is one of the aspects that makes the Amazon megaliths very similar to those in Europe.” For Calado, this type of structure may have been constructed in Amapá at a time when the local tribes were going through the process of settling in one place and expanding or developing agriculture. They needed to be attached to the land to alter the landscape with structures like megaliths.
Rego Grande and other sites with megaliths have traces of having also been used as cemeteries, another characteristic typical of this type of prehistoric structure. Funeral urns made in the aristé pottery style, marked by red designs on a white background, or dotted with engravings made on clay that was still damp, were found in these places. Pieces of decorated vases, found with the urns, indicate that the dead may have been buried alongside offerings. “The sites with large megaliths must have been reserved for the most important people in the tribe,” says Saldanha. The problem is that pottery in this style has been regularly found in prehistoric sites that have no stone monuments. Common along all of the northern coast of Amapá and in French Guyana, the elaborate aristé pottery stopped being produced after the Europeans arrived in the Americas and, according to Mariana, it cannot be associated with any current indigenous people from the region.
The two researchers, who represent two thirds of Amapá archaeology (there is only one more expert in this field in the state), excavated two ancient villages also in the Calçoene region, where the builders of the large lithic structures must have lived. They discovered traces of just half a dozen dwellings in each village. At the beginning of their work, the archaeologists were still working on the hypothesis that there might have been a complex and organized society there, with a large population and large encampments in the north of Amapá, around 1000 AD, when the first megaliths appeared. Now they believe that the change in the natural landscape of Amapá may have been produced by tribes with few members. “They seem to have lived in small, scattered villages, to have had the leadership and organization they needed to make the megaliths,” says Saldanha.