1. DIVERGENT BOUNDARIES

2. Divergent boundary of two continental plates.
Creates a __________. Example: _____________
rift valley
East African Rift

4. RIFT FORMATION

7. OCEANIC RIDGE Length 70000 km. Width 3000 – 4000 km.
Height 2 – 3 km in the
axial rift zone.
Characterized by shallow
earthquakes (focus 2- 8 km)
in the axial rift, and small in magnitude.
* First motion indicates that vertical faulting (Rifting) is the main mechanism.
Ridge is not continuous,
but offset by
transform faults.
OCEANIC RIDGE

8. Divergent
boundaries
also can
rip apart تمزق(rift) continents

10. Divergent boundaries: Chiefly at oceanic ridges (aka spreading centers)

12. SPREADING RATE AND TOPOGRAPHY OF OCEANIC RIDGE
Fast
> 70mm / year
intermediate
7-70 mm / year
Slow
7mm /year
East Pacific Rice
Carribbean
Mid Atlantic Ridge and
SW Indian Ridges
Flat topography
Intermediate topography
Rough topography
Wide magnetic strips
Intermediate magnetic strips
Narrow magnetic strips

13. How magnetic reversals form at a spreading center.
Width of strip depend on?

14. How rifting of a continent could lead to formation of oceanic lithosphere.

15. e.g., East Africa Rift (Birth) e.g., Red Sea (Young)
Doming (arching) or upwarping
3 arms: 2 successful while the third fail
e.g., East Africa Rift
(Birth)
e.g., Red Sea
(Young)
e.g., Atlantic Ocean
(Mature)

16. Pangea
was ripped apart
by such continental
rifting &
Drifted.