Sea floor spreading & subduction powerpoint

1. Seafloor Spreading and
Subduction

2. Continental drift was largely
ignored until the 1950s…
• When the USA
started mapping the
ocean floor properly,
using new techniques
• Scientists such as
Marie Tharp produced
the first detail ocean
floor maps

3. They discovered mountains and
valleys they had not expected

4. This lead to the idea of seafloor
spreading
• Scientists such as Harry Hess and Robert Dietz
looked at the maps of the ocean floor and
developed the idea of seafloor spreading.

5. Seafloor spreading

7. Evidence 4 – Magnetic Reversals

8. Sea-Floor
Spreading

9. Discovery of Sea-Floor Spreading

10. Sediment thickness

11. Patterns of Earthquakes
Where does old crust go?

12. Earthquakes

13. Depths of earthquake foci

14. Where Does Ocean Crust Go?
Hugo Benioff, 1954

15. Benioff’s Interpretation
Updated