Rocks What is a rock? a. Naturally occurring b. Solid Made of two or more minerals. Composed mostly of these eight elements: Oxygen-O; Silicon-Si; Aluminum-Al; Iron-Fe; Calcium-Ca; Sodium-Na; Potassium-K; Magnesium-Mg d. Their classification is based on how they were formed.
What is a mineral? Is naturally occurring Is a solid Is inorganic Has a fixed chemical formula Has an orderly crystalline structure Over 4000 minerals! But only eight groups commonly found in earth’s rocks.
Rock Types by Formation a. Igneous Temperatures in lower crust and upper mantle melt rock into magma. Approximately 1400 degrees C. This liquid is less dense than solid rock so it rises. As the magma rises, magma cools and hardens to form igneous rocks.
Rock Types by Formation b. Sedimentary (most common) Sediments, small pieces of rock, shells and other organic material are carried by wind or water and deposited. As layers of sediment deposit on top of each other they are compacted and cemented into sedimentary rock.
Rock Types by Formation c. Metamorphic a result of changes that occur to existing rocks. Changes are caused by high heat, pressure, or by chemical reactions.
The Rock Cycle
The rock cycle shows how the three rock types relate to each other.
weathering, crystallization, metamorphism Rock Cycle There are 4 processes of rock formation that are the links between the rock types, sediment and magma. weathering, crystallization, lithification metamorphism
Weathering is the gradual wearing down of all rock types once they are exposed at the surface.
is the cooling of magma to form an igneous rock. Crystallization is the cooling of magma to form an igneous rock.
Lithification is the transformation of loose sediment into a rock by a slight heating and/or cementation.
Metamorphism occurs when a rock is subjected to heat and pressure, transforming a rock. This can occur on any rock, even a metamorphic rock.
Fig. 2.9 MAGMA
IGNEOUS Crystallization MAGMA
IGNEOUS Plutonic Crystallization MAGMA
Volcanic IGNEOUS Plutonic Crystallization MAGMA
Weathering Volcanic IGNEOUS Plutonic Crystallization Uplift MAGMA
SEDIMENT SEDIMENT Volcanic IGNEOUS Plutonic Uplift MAGMA Weathering Crystallization Uplift MAGMA
Erosion & Transport Water Wind Ice Gravity SEDIMENT SEDIMENT Volcanic Weathering Erosion & Transport Volcanic IGNEOUS Plutonic Crystallization Water Uplift MAGMA Wind Ice Gravity
Lithification = Cementation + Compaction SEDIMENT Volcanic IGNEOUS Erosion SEDIMENT Weathering Lithification = Cementation + Compaction Transport Deposition Volcanic IGNEOUS Plutonic SEDIMENTARY Crystallization Uplift MAGMA
SEDIMENT Volcanic IGNEOUS Plutonic SEDIMENTARY METAMORPHIC Burial Erosion SEDIMENT Weathering Transport Deposition Volcanic IGNEOUS Plutonic SEDIMENTARY Increased P&T METAMORPHIC Crystallization Burial Uplift MAGMA
Can you see any shortcuts? Erosion SEDIMENT Weathering Transport Deposition Volcanic IGNEOUS Plutonic Can you see any shortcuts? SEDIMENTARY Increased P&T METAMORPHIC Crystallization Melting Burial Uplift MAGMA
SEDIMENT Volcanic IGNEOUS Plutonic SEDIMENTARY METAMORPHIC Burial Erosion SEDIMENT Weathering Transport Deposition Volcanic IGNEOUS Plutonic SEDIMENTARY Increased P&T METAMORPHIC Crystallization Melting Burial Uplift MAGMA
In Conclusion… The rock cycle demonstrates the relationships among the three major rock groups It is powered by the interior heat of the Earth As well as earth’s momentum and… The energy from the sun It involves processes on the Earth’s surface as well as the Earth’s interior It connects the “hydrologic cycle” with the “tectonic cycle”.