A weathered sign in the Minnesota River Valley proudly proclaims: “World’s Oldest Rock.” Erected in 1975, it marks a 3.8-billion-year-old gneiss — or so scientists thought.

The geologist publishes in Spain 'Listening to the Stones', where she tries to define our place in time: "Thinking of Earth as an inert and indolent piece of rock that we can deceive has led us to ...