rock types

• there are three types of rock: Igneous, Sedimentary, and Metamorphic
• each rock type is formed at different places
• rocks are usually mixtures of compounds
• igneous rocks are formed from the cooling of molten rock
• sedimentary rocks are small pieces of rock which are transported by rivers and laid down in layer
• metamorphic rocks are formed under pressure and heat
• Igneous rocks can be classified into two groups: intrusive (plutonic) or extrusive (volcanic)
• intrusive rocks cool slowly so they have large crystals
• extrusive rocks cool quickly so they have smaller crystals
• intrusive rocks cool slowly, so they have large crystals
• intrusive rocks cool slowly, so they have large crystals
• intrusive rocks cool slowly so they have large crystals
• extrusive rocks cool quickly, so they have smaller crystals
• igneous rock- igneous rocks are formed from molten lrock tht has cooled down and solidified
• igneous rocks contain randomly arranged crystals that interlock with each other.
• the size of the crystals depend on how quickly the molten magma solidify, it forms inclusive and exclusive igneous rocks
• extrusive igneous rocks form when the lava cools quickly this makes smaller crystals that need to be seen with a microscope an example is obsidian
• inclusive igneous rocks form when the lava cools slowly this makes larger crystals that can be seen without a microscope an example is granite
• sedimentary rock are layers of rocks examples are chalk and limestone
• the process of sedimentary rocks is:

  1. transport
  2. deposition
  3. sediment
  4. compaction
  5. cementation
• There are five processes that make a sedimentary rock:

  transport → deposition → sedimentation → compaction → cementation
• Metamorphic rocks are formed from other rocks which change due to heat or pressure.

  The original rocks are usually sedimentary rocks or igneous rocks. Sometimes one metamorphic rock can be turned into a different metamorphic rock.
• There are three stages involved in the formation of metamorphic rocks:

  1. Earth movements cause rocks to be deeply buried or compressed.
  2. This causes the rocks to be heated and puts them under great pressure.
  3. They do not melt, but the minerals they contain are changed chemically, and form metamorphic rocks.