ROCKS!!!

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• Any solid mass of mineral or mineral-like matter that occurs naturally as part of our planet

• 3 types Igneous Sedimentary Metamorphic

WHAT IS A ROCK?

• Interactions among Earth’s water, air, land, and living things can cause rocks to change from one type to another

• A continuous process

THE ROCK CYCLE

• Forms when lava or magma hardens.

• Lava:• Molten rock on the

surface of the Earth

• Magma:• Molten rock beneath

Earth’s surface.

IGNEOUS ROCKS

• Igneous rocks are formed by the cooling of molten rocks and the crystallization of minerals.

IGNEOUS ROCK FORMATION

• Intrusive Igneous rock: forms when magma hardens beneath Earth’s surface

• Extrusive Igneous Rock: forms when lava hardens on the surface of the Earth

TYPES OF IGNEOUS ROCKS

Igneous Rocks are classified based on their texture and composition.

CLASSIFYING IGNEOUS ROCKS

• Texture: size, shape, and arrangement of interlocking crystals.

• Course Grained: slow cooling, large crystals.

• Fine Grained: rapid cooling, small interconnected mineral grains.

• Glassy: looks like glass, extrusive igneous rocks. Ex. Obsidian

• Porphyrite: large crystals embedded in a matrix of much smaller crystals.

TEXTURE CLASSIFICATION

Composition: based on proportions of light to dark minerals

Basaltic Composition Contains many dark silicates minerals and plageoclase

feldspar Rich in magnesium and iron Ex: basalt and gabbro

Granitic Composition Made almost entirely of light-colored silicate minerals like

quartz and feldspar 0 to 25% dark minerals Biotite and amphibole

COMPOSITION CLASSIFICATION

Andesitic Composition

Between basltic and granitic composition

At least 25% dark minerals

Ultramafic Composition

Composed mainly of iron and magnesium rich mineral

Almost entirely dark minerals

COMPOSITION CLASSIFICATION

Composition and Texture

Granite Andesitic Basaltic Ultramafic

Coarse Granite Diorite Gabbro Peridotite

Fine Phyolite Andesite Basalt Kematite

Porphyritic Inside any given rock Uncommon

Glassy Obsidian, Pumice

IGNEOUS CHART

Forms when existing rocks are broken down into sediment then compacted and cemented together

ProcessesCementing Compaction

WHAT IS A SEDIMENTARY ROCK?

Weathering: Any process that break rocks into sediments

Erosion : The removal of weathered rocks

Deposition: when an agent of erosion (water, wind, ice, or gravity) loses energy, it drops the sediment

Compaction: is a process that squeezes or compacts sediments together

Cementation: takes place when dissolved minerals are deposited in the tiny spaces among the sediments

HOW DO THEY FORM?

• Classified by the way they form

• Clastic or chemical

CLASSIFICATION OF SEDIMENTARY ROCKS

• Made of weathered bits of rocks and minerals

• Grouped according to the size of the sediment.

CLASTIC SEDIMENTARY ROCKS

Texture Sediments Name of Rock

Coarse(over 2 mm in size)

Gravel - rounded Conglomerate

Gravel- angular Breccia

Medium (2mm to 1/6 mm)

Sand Sandstone

Fine (1/16 to 1/256 mm)

Silt Siltstone

Very Fine (< 1/256 mm)

Mud Shale/mudstone

CLASTIC SEDIMENTARY ROCKS

Form when dissolved minerals precipitate from water solution

Biochemical Sedimentary Rock: made from once living organisms (like shells and skeleton remains)

Ex: limestone, chalk, conquina, rock salt, and bituminous coal

CHEMICAL SEDIMENTARY ROCKS

Form when existing rocks are changed by heat and pressure

Metamorphism: means “change form”

WHAT IS A METAMORPHIC ROCK?

Heat: provides the energy needed to drive chemical reactions which causes existing minerals to recrystallize

Pressure: applied in all directions on a rock which causes spaces between mineral grains to close

Hydrothermal Solutions: hot, water based solutions that promote recrystallization by dissolving original minerals and then depositing new ones

WHAT CAUSES METAMORPHISM?

Classified by texture and composition

Foliated Rock with layered or banded

appearance Ex: Gneiss

Nonfoliated No layered or banded appearance Contains only one mineral Ex: Marble

CLASSIFICATION OF METAMORPHIC ROCKS

CLASSIFICATION OF FOLIATED METAMORPHIC ROCKSName Texture/Grain

SizeParent Rock

Slate Very fine Shale, mudstone

Phyllite Fine Slate

Schist Medium to course Phyllite

Gneiss Coarse Schist, granite

CLASSIFICATION OF NON-FOLIATED METAMORPHIC ROCKSName Texture/grain size Parent rock

Marble Medium to coarse Limestone

Quartzite Medium to coarse Quartz, sandstone

Anthracite Fine Coal