Presentation on theme: "How did all of these rocks get here?"— Presentation transcript:
1How did all of these rocks get here? The Story of RocksHow did all of theserocks get here?
2Rock types Rock types are based on the way the rocks formed! Igneous SedimentaryMetamorphic
3Igneous These rocks are formed from molten or liquid rock. Magma = liquid rock inside the EarthLava = liquid rock on the surface.
4SedimentaryThese rocks are made of small fragments of rock cemented togetherThe small fragments are broken down from larger rocks by wind, water, and other forces and carried away.Later they are deposited, buried deeper and deeper until they are compacted into rock.
5Metamorphic These rocks start as igneous or sedimentary rocks. Rocks are changed by:1) heat2) pressure3) chemical processes
15Igneous RocksThe main property of igneous rocks that allows us to identify which type of igneous rock that we have is – TextureThe texture is based on how large the crystals.Crystal size depends on how fast the rock cooled (i.e. cooling rate)
25Sedimentary RocksThe main property that allows us to group sedimentary rocks is the source of sediments.Sediments can be:1. Clastic2. Chemical3. Organic
26Sedimentary RocksClastic – These sediments are composed of fragments that can be up to a meter in diameter or so small that the fragments cannot be seen with the naked eye.
27Sedimentary RocksChemical – These fragments were dissolved in water and usually form at the bottoms of rivers, lakes, seas, and oceans
28Sedimentary RocksOrganic – These fragments are from organic material like animals and plants
29Sedimentary Rocks Common sedimentary features: Stratification (layering)Ripple marks (from waves)Cross bedding (different direction of beds)Mud cracks (dried mud)fossils (lithified animals and plants)concretions
37Metamorphic RocksMetamorphic rocks began their life as an igneous or sedimentary rock but underwent a physical change to become a new type of rock.What causes the changes?1. Heat2 Pressure3. Chemicals
38Metamorphic Rocks There are two basic types of metamorphism: 1. Contact Metamorphism2. Regional metamorphism
39Metamorphic Rocks Contact Metamorphism Occurs when rocks near a magma chamber are exposed to high levels of heat but not melted
40Regional Metamorphism Metamorphic RocksRegional MetamorphismOccurs when rocks are exposed to tectonic pressure or heat.
42Metamorphic RocksHow do we classify metamorphic rocks since they have a wide range of compositions and origins?Foliation!!Definition: Visible parallel bands(not layers)Metamorphic rocks are foliated or unfoliated
43Metamorphic RocksFoliation occurs because the mineral grains are squished by the intense heat or pressure