3.3 Plates Move Apart . Learn about: Different plate boundaries What happens when plates move apart. How the direction and speed of plates can be measured. Plate Boundaries. There are three kinds of plate boundaries Divergent Convergent Transform
Different plate boundaries
What happens when plates move apart.
How the direction and speed of plates can be measured.
This is where two oceanic plates were diverging forming new crust
This is where oceanic plates are being ripped apart magma comes up from deep within the earth’s crust and forms pillow basalts and under water vents
The Mid Atlantic Ridge is an example of oceanic-oceanic divergence
Over millions of years the continents have moved enough to create an ocean
The ridge also contains the longest mountain chain in the world
(6214 miles long)
(15 miles wide)
(6 miles deep)
Continental plates diverge in the same way as Oceanic plates
Cliffs and ridges are more easily visible in continental divergence
The East African Rift Valley formed when a three way split almost tore Africa apart
Example of a Continental rift valley.
What is the difference between?
What happens when:
Japan is part of an Island Arc formed by oceanic-oceanic convergence
Which Plate always goes under? And why?
Transform faults occur along divergent oceanic and continental plate boundaries
Plates slide past each other building up tension until the tension is released during an earthquake
Another type of tectonic activity are areas called hot spots
A hot spot is where magma rises to the earths crust melting the land and forming a line of volcanoes as the earth’s crust moves past it
In oceans hot spots form Island chains
Since the hot spot is under mafic rocks the lava flows smoothly down the mountain creating shield volcanoes like Hawaii
Hotspots below continents are highly explosive and form craters called calderas
The force required for Felsic rock is so great the eruption vaporizes the land and sends ash over large parts of continents