TERRA FIRMA Plate interactions

EARTH’S INTERIOR crust under the oceans - basalt (more dense) crust under the continents - granite (less dense) mantle comprises 80% of the earth's volume outer core is liquid inner core is solid lithosphere - rigid blocks of the crust and upper portion of the upper mantle, also known as the plates, there are 10ish major plates asthenosphere - mixture of solid and molten (plastic-like) rock zone just below the lithosphere, allows the plates to slide

There are 3 types of plate boundaries: divergent, convergent and transform faults divergent boundary- plates move away from each other and create new crustal material this occurs in the oceans, exception is the Great Rift Valley in eastern Africa rift zone is created as magma comes up from the mantle magma creates volcanoes known as ridges, example mid-atlantic ridge Earthquakes occur

Convergent boundary- plates collide, 3 possibilities due to the type of plate material 2 ocean plates (basalt) both plates will descend into the mantle destroying crustal material creating a subduction zone subduction zones have trenches and as the plate is pushed into the mantle the plate melts and rises to create volcanoes these volcanoes will form on the ocean floor and with time can extend to above sea level these volcanic islands are referred to as an island arc Examples- Japan, Mt Pinatubo Earthquakes occcur

1 ocean plate (basalt) 1 continental plate (granite) converge- the ocean plate will descend into the mantle destroying crustal material creating a subduction zone all subduction zones have trenches and as the plate is pushed into the mantle the plate melts and rises to create volcanoes volcanoes will form on the edge of the continent these volcanic mountains are referred to as a volcanic arc Examples- Andes, Mt St Helens Earthquakes occur

2 continental plates (granite) converge- neither descends into the mantle folded mountains Examples- Himalayas, Alps Earthquakes occur

transform faults- 2 plates slide past each other horizontally Earthquakes occur, no mountains are created example- San Andreas fault