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