Rocks - PowerPoint PPT Presentation

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  1. Rocks Igneous Sedimentary Metamorphic

  2. Igneous Rocks Pumice Granite Basalt Obsidian Gabbro

  3. Gabbro

  4. Obsidian

  5. Basalt

  6. Pumice

  7. Granite

  8. Igneous Rocks • Intrusive Igneous • form deep in the earth from magma. Magma cools slowly over time. Minerals grow large. • Extrusive Igneous • rocks form when molten rock erupts as lava above the surface. The lava cools quickly so there is no time for large crystals to form.

  9. Rocks Igneous Sedimentary Metamorphic

  10. Sedimentary Rocks Coal Conglomerate Shale Limestone Gabbro

  11. When mountains are first formed, they are tall and jagged like the Rocky Mountains on the west coast of North America. When mountains are old, they are rounded and much lower. What happens in the meantime is that lots of rock gets worn away due to erosion. Rain, freeze/thaw cycle, wind and running water cause the big mountains to crumble a little bit at a time. Eventually most of the broken bits of the rock end up in the streams & rivers that flow down from the mountains. These little bits of rock & sand are called sediments. When the water slows down enough, these sediments settle to the bottom of the lake or oceans they run into. Over many years, layers of different rock bits settle at the bottom of lakes and oceans. Think of each layer as a page in a book. One piece of paper is not heavy. But a stack of telephone books is very heavy & would squish anything that was underneath. Over time the layers of sand and mud at the bottom of lakes & oceans turned into rocks.

  12. Sedimentary rocks are formed from particles of sand, shells, pebbles, and other fragments of material. • All of these particles together are called sediment. • Gradually, the sediment accumulates in layers and over a long period of time hardens into rock. • Usually the only type that contains fossils.

  13. Coal

  14. Limestone

  15. Sandstone

  16. Conglomerate

  17. Shale

  18. Metamorphic Rocks Gneiss Marble Schist Slate

  19. Metamorphic rocks form deep within the Earth, when heat and pressure are applied to either igneous rocks, or sedimentary rocks. This heat, and pressure in essence cooks the rocks, changing their structure substantially.

  20. Gneiss

  21. Marble

  22. Slate

  23. Schist

  24. Kentucky Geological Survey

  25. Which of the rock strata shown is the oldest? Explain your answer: Write out the following sentences filling in the missing words. “In the rock strata diagram above, the limestone is older than the _______________ and the ________________, but is younger than the __________ and the _____________.” Make a list of everyday examples where things are built up or piled up with the oldest layer at the bottom. Taken from: