BASIC LAVA: Thin runny lava, flows long distances.
COMPOSITE VOLCANO: Steep sided cone with layers of ash and lava.
COMPRESSIONAL MARGIN: Where two plates are moving together (destructive).
CONTINENTAL PLATE: A huge section of the Earths Crust.
EARTHQUAKE: A shaking of the earths crust.
FOLD MOUNTAINS: Mountains formed by plate movements.
RICHTER SCALE: Measures the strength of an earthquake.
SHIELD VOLCANO: Gentle sides, wide base made of basic lava.
TECTONIC ACTIVITY: Changes taking place in the structure of the earth.
TENSIONAL VOLCANO: Where two plates are moving apart (constructive)
VOLCANO: A cone-shaped mountain created by lava from repeated eruptions.
Evidence of plate movement!
- Rock types
- Coal seems
- Mountain ranges
- Ancient maps
- Earthquakes and Volcanoes!!!!!!
Two plates that move past each other, rubbing against each other building up tension, then realeasing the tension in a sudden and often violent jerk. This sudden Jerk causes an Earthquake.
EXAMPLE: SAN ANDREAS FAULT - CALIFORNIA!!!
Collisional Boundry (continental + continental)!
When two land masses meet the two crash together at what is known as a collisonal boundry. They crumple and fold, some peices of lava and thrust over or under other peices. This results in a mountain range (fold mountains!) These are not volcanoes!!!!
EXAMPLE: THE HIMALYAS AND ALPS!!!
Convergent/Destructive Boundry! (ocean + continent
Two plates collide into each other. The oceanic plate is forced (subducted) underneath the continental. A deep trench is formed where the two meet. The continental plate is under pressure and the land is forced upwards eventually forming a volcano. As the oceanic plate sinks into the earth it heats up and melts. The molten rock rises up through the continental plate causing earthquakes and eruptions through the volcano formed.
EXAMPLE: THE PACIFIC OCEAN IS BEING SUBDUCTED!
Where two plates are pulling apart. A rift is formed. Magma wells up from the earths interior. It then solidifies into rock as it is cooled by the sea creating new ocean floor. Earthquakes occur along the faults and volcanos form where magma reaches the surface.
EXAMPLE: EAST AFRICAN RIFT VALLEY - UNDERWATER MOUNTAIN RANGE. ATLANTIC OCEAN!!
Fold mountains are made of sediments lifted of the seabed.
How are sediments lifted from the seabed?
There are two ideas!
1. THE LEADING EDGE THEORY!