GEL Week 4- Rock cycle and Igneous Rocks (1)

What is the purpose of the rock cycle?

The rock cycle describes the pathways that can create each of the 3 rock types

Igneous process

Internal heat melts rocks to create magma; cools and becomes igneous

Sedimentary process

Erosion creates sediments, can become sedimentary

Metamorphic process

Rocks can be squeezed and heated, changing their characteristics. This change produces metamorphic rocks

Igneous rocks

Solidified molten rock that freezes as it cools (1,000 C to 650 C)

T/F: Earth is not made up of igneous rock

False: Earth is mostly igneous rock

What is magma?

Magma- subsurface melt (molten rock beneath surface)

What is lava?

Lava- melt at the surface (magma leaving Earth’s interior and rises towards surface

Difference between lava and magma

The difference between magma and lava is significant as their varying characteristics lead to the formation of distinct rocks

How is Earth’s internal temperature described?

Geothermal gradient- temperature increases with depth (varies by location)

How does magma form?

Magma forms as existing rocks melt. It occurs in the crust and upper mantle.

Does magma move?

Yes, magma doesn’t stay put; it tends to rise upward. It is less dense-buoyant (so it rises to surface)

What are the 3 components of magma?

Solid, liquid, and gas

Solid

Mineral crystals in the melt (molten rock)

Liquid

comprised of mobile elements (mostly Si and O)

Gas

Magmas contain abundant amounts of dissolved volatile (vaporus) gas.

Name the percentage of volatiles in magma

Up to 15% volatiles- gas (Water vapor- H2O)

What is the role of element composition in magma?

Different mixes of elements yield different magmas, which lead to different rocks