Download Three types of Rocks *Notes*

Igneous, Metamorphic and Sedimentary
 A rock is a naturally formed,
solid material made up of one or
more minerals.
 What does naturally formed
mean?
 What is a solid material?
 Minerals?
 All rocks can fall into at least one of the categories.
 Rocks do not stay the same.
 They are continually changing.
 They change as a result of
 Melting.
 Heat and Pressure.
 Weathering, transportation, and deposition.
 Cementing and compacting.
 Cooling and solidifying.
 Changed by HEAT AND PRESSURE.
 The word metamorphic actually
means “changed”!
 Metamorphic rocks begin as either
sedimentary, igneous or even other
metamorphic rocks.
 Develops underground.
 Rocks from above cause heat and pressure
on the underlying metamorphic rock.
 Metamorphic rock is generally hard and
nonporous.
 What does nonporous mean?
 Rocks that form when small pieces of
rocks, minerals and shells are
deposited, buried and are squeezed
and cemented together.
 Sometimes contains fossils.
 Process of forming:
 Begins with weathering.
 What is weathering?
 Breaking down of existing rocks into
smaller pieces.
 How? By wind, water and ice carry away
these small rock pieces or SEDIMENT.
 Making new rock.
 Eventually that sediment is deposited somewhere new.
 As sediment is added, it makes LAYERS.
 As the layers build up, it adds pressure the bottom
layers are cemented together.
 Some rock layers are hard, solid and dense.
 Other layers are porous.
 Forms when MELTED ROCK COOLS and HARDENS.
 Forms in two ways
 Intrusive
 Extrusive
 Intrusive
 Over centuries trapped magma will cool and solidify
(below ground)
 Extrusive
 When lava is cooled by the temperature of the air, it
hardens to a solid.
Sedimentary rock forms in
layers.
Igneous rock forms from
melting and cooling.
Metamorphic rock forms from
heat and pressure.