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Volcanoes in our Community

Learn about the three main types of rocks - sedimentary, metamorphic, and igneous. Discover how they are formed and what makes each type unique. Explore the process of erosion and the cycle of rock formation.

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Volcanoes in our Community

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  1. Volcanoes in our Community Volcanic and Other Types of Rocks and What Makes Them Science Std: Geo # 3c

  2. There are 3 main types of rocks • Sedimentary • Metamorphic • Igneous

  3. There are 3 main types of rocks • These rocks all change from one type into another Sedimentary Rock Pressure Pressure Sediment Silt and Dirt Weathering Weathering Sediment Silt and Dirt Heat and Pressure Weathering Melting Weathering Heat and Pressure Metamorphic Rock Igneous Rock Cooling Melting Lava and Magma Melting

  4. All rocks are made from…. • Minerals that can be described by…. • A Chemical Formula • How it Looks And Acts • Porous (lots of tiny bubble holes called vesicles Each mineral has a unique (only one) combination of atoms • Granular (lots of small grain parts) • Smooth / Rough • Hard / Soft • Shiny / Dull • How easily it breaks

  5. All rocks are made from…. • All Minerals have Crystals Crystals are atoms and molecules that are grouped and stuck together in a neat pattern Like toy soldiers lined up, they have a definite pattern that keeps going on and on We’ll talk more about crystals later….

  6. Lets look at the 3 types of rocks • How are they formed and look Sedimentary Rock First we will look at Igneous Rocks Metamorphic Rock Igneous Rock

  7. Lets look at the 3 types of rocks • Molten rock (magma and lava) cools and makes Igneous Rock Sedimentary Rock • Depending on how fast it cools, it looks very different • If it cools fast, it makes small crystals that you can’t see First we will look at Igneous Rocks • If it cools slowly, it has time to make big crystals that you can easily see Metamorphic Rock Igneous Rock

  8. Lets look at the 3 types of rocks • There are 2 main types of igneous rocks Igneous Rock • Extrusiveor Volcanic igneous rocks Normally come to the surface They cool quickly Little or no crystals seen in the rocks (Basalt) Basalt Igneous Rock Very few crystals makes the rock look like black glass (Obsidian) Obsidian Igneous Rock

  9. Lets look at the 3 types of rocks • There are 2 main types of igneous rocks Igneous Rock • Intrusive or Plutonic igneous rocks Cools slowly under the surface of the Earth Granite Big crystals formed easy to see with eye Geode Sizes and shapes vary widely from boulders to whole mountain ranges Can only see when lifted up or erosion shows them Quartz Diamond

  10. Lets look at the 3 types of rocks • Regardless of the type of rock…. Igneous Rock • The color of the rock depends on the minerals in the magma Light colored rocks have high silica content Darker colors are from iron and magnesium Medium colored rocks have combinations of light and dark minerals Dark colored rocks have low silica content and have more iron and magnesium

  11. Lets look at the 3 types of rocks • The next type of Rock is Sedimentary Sedimentary Rock Igneous Rock • There are 3 types of sedimentary Sandstone Made from sediment only Limestone Made from pieces of fossils and sediment Conglomerate Made from other bits of rock and sediment

  12. Lets look at the 3 types of rocks • The last type of rock is Metamorphic Metamorphic Rock Sedimentary Rock • These can be made by….. Heat alone Heat and Pressure This is where the rocks are heated and changed without having a lot of pressure on them This is where there is both heat and a large amount of pressure to change the rocks Becomes Limestone Marble

  13. So where can these rocks form? • Igneous rocks come from volcanic events Igneous Rock Metamorphic Rock • But you don’t have to have an eruption to make igneous rocks….. Magma Pockets Lava on the surface Magma can rise up and collect in a pocket Lava comes to the surface On the surface it is quickly cooled by air or water The magma can cool and form igneous rocks It cools slowly so it can make large crystals So it forms small crystal rocks

  14. So where can these rocks form? • Metamorphic rocks form primarily at plate boundaries. Metamorphic Rock Igneous Rock Convergent Plates Transverse Plates 2 plates rub together 2 plates crush and rub together Harder to do here because you need heat to have the change High pressure and temperatures change the rocks Unless the transverse boundary is deep, you won’t get the heat needed They can then work their way up or we can dig down

  15. So where can these rocks from? • Sedimentary Rocks usually form under water Sedimentary Rock Metamorphic Rock Sand and silt pile up on the ocean floor Over time (millions of years) the silt on the top presses down on the silt on the bottom After a long time, the silt on the bottom presses and cements together into new sedimentary rocks

  16. Where do the rocks go? Metamorphic Rock Igneous Rock Sedimentary Rock All rocks erode and wear away due to water and weather Rocks are subducted at convergent plate boundaries and are melted back into magma Rocks under the surface can break apart (fracture) speeding up the erosion Eventually, all rocks are recycled into another type of rock

  17. Questions?

  18. Your Homework….. Start Studying for the next Test On Volcanoes Have your Flash Cards Ready for the Review

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