A hidden shard of ancient crust has been detected where California’s San Andreas system collides with the Cascadia subduction zone, reshaping how I understand the tectonic engine of the West Coast.

The solid ground that we all live on forms a thin crust around the Earth. It’s no more than 50km thick - and it’s just the upper part of the lithosphere. Below it is the upper mantle. It’s mostly ...

Plate tectonics explains the movement of Earth's surface. When you purchase through links on our site, we may earn an affiliate commission. Here’s how it works.