The rock cycle
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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. Intrusive Extrusive. Intrusive Igneous. Extrusive Igneous. Basalt Low Silica – Shield Volcano.

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The rock cycle


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

Igneous rocks
Igneous Rocks



The rock cycle

  • Basalt

  • Low Silica – Shield Volcano

The rock cycle

The rock cycle

The rock cycle

Sedimentary rocks
Sedimentary Rocks

Clastic – rock fragments - sediments

Organic – shells – dinosaur bones

Chemical – salt – Dead Sea


Ripples in Stream bottoms!

The rock cycle

  • 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

The rock cycle

  • Strata surface

  • Layers!

  • Grand Canyon

  • Sedimentary & Metamorphic

Jurassic marl
Jurassic Marl surface

  • Lyme Regis, UK

Sedimentary cliff
Sedimentary cliff surface

Cardiff, Cymru

The rock cycle

Metamorphic rocks
Metamorphic Rocks surface

Contact or Thermal Metamorphism


Regional Metamorphism

The rock cycle

  • Thermal metamorphic rocks surface /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

The rock cycle

Regional metamorphic surfacerock 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
Classification of Metamorphic Rocks surface

  • 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.

The rock cycle

  • Gneiss surface

  • Foliated or Nonfoliated??

The rock cycle

Igneous surface

/\ Melting\/ Heat&Pressure

Melting /\Erosion \/



<-ErosionHeat & Pressure ->

Word picture definition sentence
Word, Picture, Definition, Sentence surface

  • Mineral Silicate

  • Rock Luster

  • Crystal Streak

  • Gem Hardness

  • Ruby Moh’s Scale

  • Diamond Cleavage

  • Sapphire Fracture

  • Fossil Ore

  • Crystal System Texture

  • Specific Gravity Emerald

The rock cycle

The rock cycle


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


  • 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
Where is it all Found? surface

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

  • What about the rest of North America?

The rock cycle

The rock cycle

The rock cycle

The rock cycle

The rock cycle

The rock cycle

The rock cycle

  • All surface

  • With some more detail