ABSTRACT

In a geological sense, everything is transient, even mountains grow and move, flow, shrink, and perish – eroded by water and ice, exploding in volcanic ecstasies, melting and slipping back into the torrid heat of the Earth’s mantle. The very ground we stand on shifts, sometimes violently as the earth quakes, sometimes so very slowly that we would never dream of questioning its permanence. Yet rocks are the earth’s continental drifters, continually travelling across the planet in the very act of constituting that thin lithospheric crust, just a few kilometres in depth, on which all life, all earthlings, are entirely dependent.