Constructive Plate Boundary – initial stage Rift Valley e.g. East African rift valley
Rift Valley with stepped faults, and tilted blocks (horsts) Initial doming from upwelling magma Leads to Y-shaped rifting.
A shallow sea basin may form – lots of evaporite salt deposits. Middle Stage
Mid ocean ridge created by sea floor spreading. Magnetic stripes as evidence for the spreading. Fissure volcanoes e.g. Iceland Later stage
Underwater mountain range Central rift valley Offset by transform faults
Destructive Plate Boundary – type 1 Ocean plate v. Ocean plate Ocean trench e.g. Aleutian trench Island arc volcanoes e.g. Aleutians (off Alaska)
Pacific Ring of Fire
Ocean plate v. Continental plate (Sometimes called a SUBDUCTION ZONE) Ocean plate subducts as it is denser Ocean trench e.g. Peru-Chile trench Cordillera range of Young Fold Mountains e.g. Andes Andesitic volcanic peaks e.g. Nevada del Ruiz Destructive Plate Boundary – type 2
Destructive Plate Boundary – type 3 Continental plate v. continental Plate collision A collision zone Major fold mountains e.g. Himalayas and High Plateau e.g. Tibet e.g. Ocean plate carrying India drifted northwards until India collided with Eurasian plate.
Conservative Plate Boundary No volcanic features Plenty of earthquakes e.g. San Andreas fault. Fault line scarp slopes Horizontal movement faults
Fault displacement features
Mid ocean ridge Transform fault Conservative Plate Boundaries are transform faults which displace mid ocean ridges in Constructive plate Boundaries