Physical Science Sedementary and metamorphic rocks

Sedimentary Rocks Most common in the upper portion of the crust and surface Form a thin and extensive blanket over igneous rock They can provide information about geological events and time From yahoo images

How are Sedimentary Rocks Formed Weathering Erosion Sedementation From yahoo images

Weathering Weathering – braking down or decomposing of surface rock Mechanical Weathering – physically breaking rock into smaller pieces Chemical weathering – reactions in water to break down rock From yahoo images

Erosion process by which weathered rock particles are removed and transported by water wind or ice From yahoo images

Sedimentation – deposition of rocks and minerals in layers over time From yahoo images

Sedimentation The large the sediment, the stronger the wind or water current must be Typically water currents get weaker as they move from their source So larger particles tend to be deposited before smaller ones The size and shape of particles in a sediment give clues to the time and distance of transportation

Sedimentation Sedimentary rock forms in two steps compaction and cementation Compaction As layers form on layers – pressure is increased on lower sediments – the rocks are compacted together

Sedimentation Cementation As pressure increases, water is squeezed out of the rock leaving small pores. The water tends to contain silica, calcite and hematite in solution as it is squeezed out, these mineral precipitate partially filling the pores and cementing the rocks together.

Clastic Sedimentary Environments Stream deposition

Clastic Sedimentary Environments Wind deposition

Clastic Sedimentary Environments Deltas and Alluvial fans water speed slows as stream reaches an open flat valley deposition occurs and forms a fan shaped deposit From yahoo images

Chemical sedimentary environments Sediments produced from mineral precipitation from water Either by reaction of ions to form solids or by the evaporation of water stalactites/stalagmites and corral reefs From yahoo images How Do They Form

Metamorphic Rock – rock formed under high heat and pressure without melting From yahoo images

Metamorphic Rock Recrystallization – Re structuring of chemical bonds – many time with the loss of water or CO2 Mechanical deformation – rocks under pressure may bend or flow plastically in to folds or sheer and break up From yahoo images

Types of metamorphism Dynamic – mechanical deformations – shearing, grinding, flattening, elongation– produces broken and distorted textures Contact – formed by the intrusion of magma due to the high temperature altering the structure on the surface of the rock surrounding the intrusion From yahoo images

Contact Metamorphism

Types of metamorphism Regional – alteration due to both thermal and mechanical From yahoo images

The Rock Cycle