rocks

Igneous

metamorphic

Sedimentary

The Rock Cycle

IGNEOUS ROCKS

• The only rocks that give us window into new rock formation.

• They are formed from magma that is sent through volcanic activity to the surface.

• Igneous rock forms when magma cools and makes crystals.

• Magma is a hot liquid made of melted minerals. When magma pours onto the earth’s surface it is called lava.

• The minerals can form crystals when they cool. • Igneous rock can form underground, where the

magma cools slowly. Or, igneous rock can form above ground, where the magma cools quickly.

• The crystals grow together and form one igneous rocks.

IGNEOUS ROCKS

IGNEOUS ROCK

Depending on the speed the magma reaches the surface, the hardened igneous rocks that is formed can looked very different.

Igneous

The Rock Cycle

Igneous means “born of fire”

Igneous

The Rock Cycle

Igneous means “born of fire”

INTRUSIVE IGNEOUS ROCKS – When igneous rocks are formed by magma that cools BENEATH Earth’s surface, they are called intrusive igneous rocks

EXTRUSIVE IGNEOUS ROCKS – When igneous rocks are formed by LAVA ON Earth’s surface, they are called extrusive igneous rocks

Two Types of Igneous Rocks

IGNEOUS ROCK ORIGIN

• Came from the Latin word “ignis” meaning fire

How is it studied?

• The study of igneous rock is the study of magma.

HOW MANY % IS IGNEOUS ROCK ON OUR CRUST?

Over 95% of the top 10 miles of the crust is made up of igneous rock formed from lava eruptions.

• It is formed from lava eruptions of at least 7000C –the temperature needed to melt a rock.

• It takes very high temperature to melt a rock.

• The deeper you go into the Earth the hotter the temperature. Sample temperatures taken at different depths commonly increase about 300C per km (900 F per mile)

HOW HOT IS IT?

GEOTHERMAL GRADIENT

The rate of temperature increase compared to depth.

• TEXTURE

• COMPOSITION

WHAT OTHER THINGS CAN AFFECT THE MELTING OF ROCK?

HOW?

SHOW ME HOW..

HOW PRESSURE AFFECTS ROCK MELTING

The greater the pressure applied to the solid rock the more force is applied to its atoms.

This force packs the rock into denser and denser structures.

Rocks deep in the mantle are under a lot of pressure. When a tectonic plate shifts or a crustal fissures forms releasing some of the overlying pressure, tightly compressed rock loosens up,atoms aligned and held in a certain pattern within the rock structure are then able to shift.

Their movement becomes freer and a lot more like a liquid state.

How are we going to call a melted rock?

MAGMA- is the sea of melted rock found in the mantle.

This super-heated liquid is hotter and cooler depending on its location and activity within the mantle’s circulation currents.

What is the instrument used?

PYROMETER- the instrument used to measure the temperature of the lava from a distance. It is an optical measuring device that allows temperature measurements to be taken safely.

Freshly blasted magma has been measured at temperatures between 1000- 12000C.

Can we touch a cooled magma easily?

NO!

once magma arrives, it cools. The cooler the lava gets, the greater its viscosity and the slower it moves.

But don’t get to close, lavas that are barely moving have been measured at temperatures of 8000C.

Viscosityis the resistance that a fluid has to flow because of its chemical and structural composition.

What affects magma’s viscosity?

1. Temperature- the hotter it gets, the runnier it gets. Heat excites the atoms and adds energy.

2. Silica – silicate minerals have big tetrahedral (pyramid-shaped) structure. They are linked together by shared oxygen molecules. However, silicate molecules in hot magma form crazy chains, sheets, and big matrices. As these linked molecules gets larger, the magma becomes more and more viscous and doesn’t want to flow. the number of tetrahedral bonds that can be formed into linked molecule groups depends on the amount of silica present in the magma.

Put simply, silica in magma gets hard when it cools.

What affects magma’s viscosity?

2. Silica – silicate minerals have big tetrahedral (pyramid-shaped) structure.

They are linked together by shared oxygen molecules. However, silicate molecules in hot magma form crazy chains, sheets, and big matrices. As these linked molecules gets larger, the magma becomes more and more viscous and doesn’t want to flow. The number of tetrahedral bonds that can be formed into linkedmolecule groups depends on the amount of silica present in themagma. Put simply, silica in magma gets hard when it cools.

Remember:

The number of tetrahedral,

The linked group silicates,

The VISCOSITY