Sedimentary Rock

Sedimentary RockSedimentary RockSedimentary rock is created when existing rock breaks down into sediments, and then the sediments are recombined by compaction and cementation

Sedimentary RockSediments are created by three forces:WeatheringErosionDepositionWeatheringWeathering is any process that breaks down rock.

There are two types of weatheringChemical weatheringMechanical weathering

Chemical WeatheringChemical Weathering is the transformation of rock into one or more new compounds

Water is the most important agent of chemical weatheringMechanical WeatheringMechanical weathering occurs when physical forces break rock into smaller and smaller pieces without changing its compositionMechanical WeatheringThree forces account for the majority of mechanical weathering:Frost wedging UnloadingBiological Activity

Frost WedgingWhen liquids freeze they expand, causing rock to break apart.UnloadingUnloading occurs when pressure is removed from a rock body causing it to expand and break

Biological ActivityThe activities of plants and animals can cause rock to break apart

For example tree roots can break through rock layers, or borrowing animals creating holes in rock.

ErosionErosion is the removal of rock and its movement by water, wind, ice, or gravity.DepositionWhen water, wind, ice or gravity loses energy the sediments are released and deposited in a new area.

Sediments are deposited according to size, with larger sediments being released firstSedimentary RockCompaction and cementation are the two processes that change sediment into sedimentary rock.CompactionCompaction is a process that squeezes, or compacts sediments

CementationCementation takes place when dissolved minerals are deposited in tiny spaces among the sediments.

These minerals hold the sedimentary rocks togetherClassification of Sedimentary RockSedimentary rocks like igneous rock can be classified into two groups based on how the form:Clastic Sedimentary RockChemical Sedimentary RockClastic Sedimentary RockClastic Sedimentary Rocks are created when weathered bits of rocks or minerals are cemented togetherChemical and Biochemical Sedimentary RocksChemical Sedimentary rocks are created when dissolved minerals precipitate from water solutions

Biochemical Sedimentary rocks are created when living or once living materials are cemented togetherFeatures of Sedimentary RockSedimentary rock can have unique features that can help us interpret the history of the Earth.

Some Features include:RipplesMud CracksFossils