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Earth Science- Rocks

Sedimentary and Metamorphic rocks

 Rocks formed when sediments are cemented or compacted once these sediments are deposited.
 Constitutes about 5% of the Earths crust.
 Many of these rocks also contain fossils.
 Many of these rocks are important economically. (Energy resources)
Classification of sedimentary rocks

 Can be classified as 1) detrital and 2) chemical

 1.Detrital: Rocks formed mostly by mechanical weathering
 Grouped based on particle size:
-Coarse (Ex . Conglomerate, breccia)
-Medium (ex. Sandstone)
-Fine (Ex. Siltstone)
-Very Fine (Ex. Shale

 2. Sedimentary rock that is formed from chemical sediments, which are precipitated from solution.
 Formed from chemical weathering
 EX. Limestone, travertine, coal, coquina, rock gypsum, rock salt.
Metamorphic rocks

 Rocks formed from metamorphism (transformation of one rock to another)
 Metamorphism occurs when preexisting rock is subjected to temperatures and pressures unlike those in which it is formed.
Metamorphism

 Slight changes low grade metamorphism) to Substantial changes ( high grade )
 Shale turns into slate with heat and pressure.
 2 setting of metamorphism
 1)thermal ( contact)- rock is exposed to magma
 2)Regional-tocks are exposed to   high temperature pressure (mountain , building)
Agents in Metamorphism

 Heat
 Pressure stress)
 Chemically active fluids( water vapor , carbon oxide)
Metamorphic Texture
 Foliated- consists of layers (slate , schist   and gneiss)
 Non-Foliated-Lacks layers ( anthesite , marble

Landscapes fabricated by water

 Water is everywhere on earth
 Primarily located in the hydrosphere
 975 of the water on Earth is stored in the oceans.
 A bulk of the non-ocean water is located in glaciers (about 2.1%)
 A smaller percentage is found in groundwater, freshwater lakes, soil and the atmosphere.
 Water can exist in three physical states: solid, liquid, or gas.
 Constantly moving in the hydrosphere....