David Grann:

In cleared-away areas of the upper Amazon basin, researchers, using satellite imagery, have recently pinpointed a vast network of monumental earthworks, including geometrically aligned roads and structures, constructed by a hitherto unknown civilization.

Martti Paerssinen, Denise Schaan, and Alceu Ranzi:

It's an ill wind that blows nobody any good. The combination of land cleared of its rainforest for grazing and satellite survey have revealed a sophisticated pre-Columbian monument-building society in the upper Amazon Basin on the east side of the Andes. This hitherto unknown people constructed earthworks of precise geometric plan connected by straight orthogonal roads. Introducing us to this new civilisation, the authors show that the 'geoglyph culture' stretches over a region more than 250km across, and exploits both the floodplains and the uplands. They also suggest that we have so far seen no more than a tenth of it.

Grann:

The latest discovery proves that we are only at the outset of this archeological revolution--one that is exploding our perceptions about what the Amazon and the Americas looked like before the arrival of Christopher Columbus.

Charles C. Mann, author of 1491:

I felt alone and small, but in a way that was curiously like feeling exalted.

Martin Schwartz:

Science makes me feel stupid too. It's just that I've gotten used to it.

Have you read Grann's The Lost City of Z?

Pre-Columbian geometric earthworks in the upper Purus: a complex society in western Amazonia