Lost civilization in the upper Amazon basin

[Watser?]

It's kinda weird, I am reading the book 1491 about the Americas before Columbus which mentions earthworks in the Amazon pointing to a possible lost civilization there. This is from yesterday's Sunday Times:

The journal Antiquity has published a report showing more than 200 massive earthworks in the upper Amazon basin near Brazil’s border with Bolivia. From the sky it looks as if a series of geometric figures has been carved into the earth, but the archeologists and historians who published the report believe these shapes are the remains of roads, bridges, moats, avenues and squares that formed the basis for a sophisticated civilisation spanning 155 miles, which could have supported a population of 60,000.

Google Earth helps find El Dorado - Times Online

ETA: I suppose this should be in the History forum...