Seismic data indicate
Lithosphere is split into several plates
- Plates are 60-100 km thick but may be 100’s or 1000’s of km across
- Plates are composed of oceanic crust, continental crust, or combinations of oceanic & continental crust
- To fit on curved earth’s surface, lithospheric plates have 3D shape that resembles a dinner plate
Locate plate boundaries by occurrence of earthquakes
- Other geological phenomena, such as volcanic activity and mountain building, occur along plate boundaries