The Oldest Rock on Earth

The Oldest Rock on Earth

When geologist Hanika Rizo goes into the field she spends most of her time looking at her feet. Simply by trekking across the stark Arctic landscape in Northern Quebec, and paying close attention to the ground, she can glean clues about deep time in the color, texture, and arrangement of the solid outcrops of ancient rock that lie exposed here. Large, bauble-like shapes in the magma—“pillow lava”—speak of contact with water. Finding vestiges of …