Rock Types

Introducing the different types of rocks. Year 7 Class

1. What are rocks?

2. Types of rocks The 3 types are: Igneous Sedimentary Metamorphic

3. Igneous rocks Igneous rocks are formed from molten rock called magma. They are mostly crystalline (made up of interlocking crystals) and usually very hard to break. E.g. granite, basalt, andesite. Granite Basalt

4. The formation of igneous rocks magma Sedimentary rocks volcano Extrusive igneous rocks are cooled quickly so small crystals form (e.g. basalt). Intrusive igneous rocks are cooled more slowly so large crystals form (e.g. granite).

5. Basalt pillars These pillars were formed when lava cooled on the Earth’s surface.

6. Sedimentary Sedimentary rocks are formed from sediment grains deposited by water, wind or ice. They are always formed in layers, called “beds” or “strata”, and quite often contain fossils. E.g … Sandstone Limestone Chalk

7. The formation of sedimentary rocks These were formed from layers of sediment which were squeezed together. new deposits layers of sediments getting older sea/lake/river land rivers

8. Metamorphic Metamorphic rocks were once igneous or sedimentary rocks, but have been changed (metamorphosed) as a result of intense heat and/or pressure within the Earth’s crust. E.g … Slate Marble Gneiss, pronounced ‘nice’

9. Metamorphic rocks are formed by the effect of extreme pressures and temperatures deep within the Earth. This alters the structure of the existing rock. Metamorphic rock - formation

10. The formation of metamorphic rocks magma Sedimentary rocks sedimentary rocks are changed here due to heat and pressure. volcano

11. Continent collision causes metamorphism and huge folds like this one in Scotland. Metamorphic rocks

12. Rock type Definition Formation Example Igneous Rocks formed of interlocking crystals. Tough, hard and resistant to erosion Formed by the cooling of molten magma either underground (intrusive) or on the ground (extrusive) due to volcanoes Basalt, granite Sedimentary Formed in layers called strata. Often contain fossils. Some are tough and others are weaker than igneous or metamorphic rocks Formed by the compaction of sediments, usually deposited by the sea. Sandstone, limestone, shale, clay Metamorphic Also formed of interlocking crystals. Very tough and resistant to erosion Formed by heat and/or pressure changing existing sedimentary or igneous rocks to metamorphic rocks Slate , marble

13. sea volcano rocks are broken up by the action of weather magma slow solidification high pressure and temperature transportation and deposition rises to surface where it cools rapidly melt rocks rise to surface by uplift and erosion Igneous rocks basalt Igneous rocks granites magma Metamorphic rocks slate and marble Sedimentary rocks mudstone

14. sea volcano Igneous rocks basalt Igneous rocks granites rocks rise to surface by uplift and erosion rocks are broken up by the action of weather magma Metamorphic rocks slate and marble Sedimentary rocks mudstone slow solidification high pressure and temperature transportation and deposition rises to surface where it cools rapidly melt

15. Homework: Task – imagine you are a rock, describe your journey through the rock cycle. Things to include: Are you an igneous, metamorphic or sedimentary rock? What type of rock are you e.g. granite, limestone. Rock On!