We recently came across this interesting story about ancient earthworks in the state of Acre, Brazil. Most versions of the story call the earthworks geoglyphs but technically, geoglyph should only refer to a feature that was specifically created either as art or to have some meaning, whereas it is unknown what purpose these earthworks served. Having said that, the Wikipedia page on Geoglyph features a photo of one of the Brazilian earthworks.
We found it frustrating that most versions of the story do not give coordinates for any of the earthworks, but eventually we found this article which features a KML file with locations of 440 of them.
The earthworks have only been found where the forest has been cleared. It is possible that the ancient Amazonians preferred the same locations that the current farmers who are clearing the land do, but it is quite likely that there are still many more earthworks to be found in uncleared areas. In addition, it is notable that the extent of earthworks shown in the KML file closely matches the extent of high resolution imagery, suggesting there are many more to be found as more imagery becomes available. This fact highlights the usefulness of Google Earth as a valuable tool for archaeologists. Some nearby regions have fresh imagery from 2016 so it is probable that more discoveries are already being made.
Looking around ourselves we started to see all sorts of shapes, such as the irregular circular ditch below:
But not being trained archaeologists we have no idea whether or not this is a recent excavation or an as yet unmarked ancient site or possibly just a natural feature that looks like a man made ditch.