Last week, Greenpeace activists provoked international outrage when they undertook a publicity stunt, trespassing on the Nazca Lines World Heritage Site. Newly released done footage shows how much damage they left behind.

As PBS Newshour reports:

The Nazca figures were drawn between 500 BC and 500 AD by removing a thin patina of dark rocks covering light sand. This is one of the driest regions of the world, and the lack of water and wind has helped preserve the lines for centuries.

But they're still quite fragile. "When you step on it, you simply break the patina and expose the bottom surface," said Peru's Deputy Culture Minister Luis Jaime Castillo . "How long does it take for nature….to again create a patina? Hundreds of years? Thousands of years? We really don't know."

When archaeologists visit the site, they wear special pads on their shoes [below] to broadly distribute their weight. By contrast, photos taken by Peru's culture ministry showed footprints and overturned rocks, allegedly by Greenpeace demonstrators.