ONLY WRITE DOWN THOSE NOTES THAT ARE IN RED

RocksRocks

A rock is a hard material made of one or more minerals

Or anything that when you pick it up and throw it at someone it produces the reaction: "Owww! Why did you hit me in the head with a rock?"

The dictionary is no use here: Rock n: a large mass of stone; a concreted mass of

stony material; consolidated mineral matter I love this one: something like a rock in firmness

By the way, a stone is " a piece of rock"! A rock can be made of only one mineral entirely (monomineralic) or a mixture of many minerals (polymineralic)

Where are rocks found?

• Rocks are found in Earth’s mantle and crust

• This is because the inner core and outer core are too hot. The iron and nickel in these layers cannot solidify into rocks

• Rocks from different distances

3 groups of rocks3 groups of rocks• A rock is a group of minerals joined

together in some way– IgneousIgneous – formed by the cooling &

solidification of molten rock (magma)– SedimentarySedimentary – formed by the compaction

& cementation of layers of sediment (rock fragments, organic remains, chemical deposits)

– MetamorphicMetamorphic – formed when existing rocks are CHANGED by intense heat & pressure but DO NOT MELT

• The ROCK CYCLE shows how each type The ROCK CYCLE shows how each type of rock forms & how each rock can of rock forms & how each rock can change into a different type of rockchange into a different type of rock• Rocks gradually and continually Rocks gradually and continually

change from one type to anotherchange from one type to another

The ROCK CYCLE found The ROCK CYCLE found on page 6 of the ESRTon page 6 of the ESRT

Rock Concept Map

Rock Concept Map

Igneous Igneous Rocks Rocks

ESRT ESRT page 6page 6

Igneous rocks form from the cooling or Igneous rocks form from the cooling or SOLIDIFICATION of magma (melted rock)SOLIDIFICATION of magma (melted rock)

The RECRYSTALLIZATION of minerals is The RECRYSTALLIZATION of minerals is evident in Igneous Rocksevident in Igneous Rocks

• Magma is a mixture of liquid rock, crystals, and gas

• It is characterized by a wide range of chemical compositions, with high temperature, and  properties of a liquid

• Magmas are less dense than surrounding rocks, and will therefore move upward

LIQUID HOT MAGMALIQUID HOT MAGMA

• If magma makes it to the surface it will erupt and later crystallize to form an extrusive or volcanic rock

• If it crystallizes before it reaches the surface it will form an igneous rock at depth called a plutonic or intrusive igneous rock

• Because cooling of the magma takes place at a different rate, the crystals that form and their texture exhibit different properties

intrusive igneous rocksintrusive igneous rocks• Form by the

cooling of magma UNDERGROUNDUNDERGROUND– “IN” –trusive /

“IN” the groundAlso known as

PLUTONIC

• Underground cooling is SLOWERSLOWER– Rock crystals are crystals are

LARGELARGE & have a coarse texture

gabbrogabbro

granitegranite

pegmatitepegmatite

Granite Mineral CompositionGranite Mineral Composition

extrusive igneous extrusive igneous rocksrocks

• Forms from the cooling of LAVALAVA (magma that has reached earth’s surface)

Lava flows forming Lava flows forming extrusive igneous rocks extrusive igneous rocks

(obsidian)(obsidian)

• Cools QUICKLYQUICKLY (exposed to colder air)– Rock crystals are

SMALLSMALL and rocks have a fine/glassy texture

Rate of Cooling Activity

• When I say “Go” try to find other students in the class who have the same color that you have

• When I say “Stop”, stop exactly where you are and do not move until I say “GO” again

• What happened as I gave you a longer amount of time to find each other?

Pumice is an Extrusive Igneous Rock that is Pumice is an Extrusive Igneous Rock that is VESICULAR (has gas pockets). Because VESICULAR (has gas pockets). Because

pumice formed so quickly, the rock formed pumice formed so quickly, the rock formed around the pockets of gas, creating “holes” in around the pockets of gas, creating “holes” in the rock. This allows the rock to float in water the rock. This allows the rock to float in water

because of its lower densitybecause of its lower density

Key idea:Key idea:

The The texturetexture of the of the igneous rock is igneous rock is

determined by the size, determined by the size, shape, and shape, and

arrangement of the arrangement of the mineral crystalsmineral crystals

types of magmatypes of magma• FELSIC MAGMAFELSIC MAGMA

– Light colored– Thick (high

viscosity)– Contains high

amounts of silica•Granite

• MAFIC MAGMAMAFIC MAGMA– Dark colored– Thin (low

viscosity)– Contains high

amount of magnesium & iron•Basalt

Mafic or Felsic?

the “bells & whistles” for the “bells & whistles” for identifying an IGNEOUS identifying an IGNEOUS

rockrock

Igneous rocks have obvious CRYSTALSRYSTALS

If you see minerals, it’s probably igneous!

Igneous Definitions

• Pluton: Intrusion of magma into Earth’s crust, creating igneous rock formations such as dikes, sills, laccoliths, volcanic necks and batholiths

• Dike: Sheet of igneous rock that cuts across rock layers vertically

• Sills: Sheet of igneous rock forced between rock layers parallel to the rock layers it intrudes

Final Igneous Definitions

• Laccoliths: A dome-shaped mass of intruded igneous rock

• Batholiths: A large mass of igneous rock exposed by erosion at Earth’s surface; forms the core of many mountain ranges