Sedimentary rocks



  • Sedimentary rocks are formed by sediment that is deposited over time, usually as layers at the bottom of lakes and oceans.

  • This sediment can include minerals, small pieces of plants and other organic matter.

  • The sediment is compressed over a long period of time before consolidating into solid layers of rock.

  • Sedimentary rocks forms layers called strata which can often be seen in exposed cliffs.

  • Sedimentary rocks cover the majority of the Earth's rocky surface but only make up a small percentage of the Earth’s crust compared to metamorphic and igneous types of rocks.

  • Examples of sedimentary rocks include limestone, sandstone, mudstone, greywacke, chalk, coal, claystone and flint.

  • Limestone forms the metamorphic rock marble when subjected to extreme heat and pressure over time (metamorphism).

  • Sandstone forms the metamorphic rock quartzite.

  • Mudstone forms the metamorphic rock slate.

  • Chalk is a soft, white form of limestone.

  • Flint is a hard, sedimentary form of the mineral quartz.


  • Make a fossil cast or check out our rock sorting lesson plan.