The Rock Cycle

One kind of rock turns into another which turns into another which turns into another

which turns into another

Where it all begins

Igneous Rocks IntrusiveExtrusive

Intrusive Igneous

Extrusive IgneousExtrusive Igneous

• Basalt

• Low Silica – Shield Volcano

• Andesite – lava from the Andes

• High Silica - Stratovolcano

• Pumice – floating rock!!!

• High SilicaStratovolcano

• Rhyolite

• High Silica – Stratovolcano

Sedimentary RocksClasticClastic – rock fragments - sedimentsOrganicOrganic – shells – dinosaur bonesChemicalChemical – salt – Dead Sea

Layers!!!

Ripples in Stream bottoms!

• Sedimentary rocks cover about three-quarters of the earth's surface

• Clastic sedimentary rocks are made up of rock fragments, called sediments, that have been eroded from one place and moved to another by water, ice, wind, or gravity. In time, the sediments are buried, compacted and cemented together to form sedimentary rocks. Examples include conglomerate, sandstone, and shale.

• Other sedimentary rocks are “chemical” or “organic”.– Chemical sedimentary rocks are formed by the

precipitation or evaporation of minerals from solution in an ancient seawater. Examples include limestone, gypsum, and halite (rock salt).

– Organic sedimentary rocks are formed by the accumulation of dead plant and animal matter which is then compacted together. Examples include peat, coal and oil

• Strata• Layers!• Grand

Canyon• Sedimentary

& Metamorphic

Jurassic Marl

• Lyme Regis, UK

Sedimentary cliff

Cardiff, Cymru

• Ayers Rock / Uluru

Sedimentary rock from rivers - exposed due to erosion

Monolith!!!

Metamorphic Rocks

Contact or Thermal Metamorphism

andRegional Metamorphism

• Thermal metamorphic rocks / Contact metamorphic rocks.• This type is often associated with igneous rocks.• Because of the high heat, the “regular” rock (known as

country rock), near the hot rock is often altered. • The pressure involved is usually negligible. • Alteration of the rock is generally localized (close to the hot

rock) in what is known as a metamorphic aureole or halo.

x = Slight Metamorphism

X = Intense Metamorphism ^ = Igneous rock

Regional metamorphic rock is usually the result of extreme pressure. These are commonly associated with mountain building events and are often associated with plate boundaries at continental margins.

• Pressure squeezes the mineral grains of sedimentary rock together. This eliminates the pore spaces, and fluids.

• With more pressure, the mineral grains will form a tightly interlocking mosaic.

• With even more pressure, the crystals may reform into fewer but larger grains. – This process is known as recrystallization. The recrystallized mineral

may remain the same as it was, or it may be a new, more dense mineral.

Classification of Metamorphic Rocks

• Metamorphic rocks can be subdivided into foliated and nonfoliated types.

• Foliated means there are mineral grains aligned parallel to each other. This results in a layered appearance.

• A Nonfoliated metamorphic rock generally consists of equaldimensional grains. You can’t see layers

• A rock can also be identified by its metamorphic grade. This is simply a description of the overall intensity of metamorphism the rock was subjected to. What this implies is that a low-grade metamorphic rock shows textural or mineralogic evidence of having been subjected to low pressures and/or temperatures.

• Gneiss

• Foliated or Nonfoliated??

Sedimentary Metamorphic

Igneous

/\ Melting\/ Heat&Pressure

<-ErosionHeat & Pressure ->

Melting /\Erosion \/

Word, Picture, Definition, Sentence• Mineral Silicate• Rock Luster• Crystal Streak• Gem Hardness• Ruby Moh’s Scale• Diamond Cleavage• Sapphire Fracture• Fossil Ore• Crystal System Texture• Specific Gravity Emerald

•END

SEDIMENTARY TO METAMORPHICSEDIMENTARY TO METAMORPHIC

• The following is a very general progression from sedimentary rock to metamorphic rock based primarily on pressure.

• SURFACE MUD• 5 km DEEP SHALE (sedimentary)• 10 km DEEP SLATE (low grade metamorphic)• 15 km DEEP SCHIST (Garnet appears)• 20 km DEEP GNEISS (high grade metamorphic)• 25 km DEEP HORNFELS (Cordierite appears)

Where is it all Found?

• Hawai’i is easy enough, it’s all Volcanic!

• What about the rest of North America?

• Shaded Relief

• Sedimentary

• Metamorphic

• Volcanic

• Plutonic

• All

• All• With

some more detail