Download Rocks

yes no Was this document useful for you?
   Thank you for your participation!

* Your assessment is very important for improving the work of artificial intelligence, which forms the content of this project

Document related concepts

Large igneous province wikipedia, lookup

Algoman orogeny wikipedia, lookup

Tectonic–climatic interaction wikipedia, lookup

Sedimentary rock wikipedia, lookup

Igneous rock wikipedia, lookup

Clastic rock wikipedia, lookup

Weathering wikipedia, lookup

Geology of Great Britain wikipedia, lookup

Great Lakes tectonic zone wikipedia, lookup

The Rock Cycle
• Magma—molten material that forms inside
the Earth
– It crystallizes either beneath the surface or as
a result of volcanic activity to make
• Igneous Rock
– It weathers, is transported, and deposited to
• Sediment
– It goes through lithification (changes into rock)
to become
The Rock Cycle
• Sedimentary Rock
– If it is exposed to great heat and pressure
because of mountain building or being
intruded with magma, it will change into
• Metamorphic Rock
– If it is exposed to more heat and/or pressure,
it will melt and become
• Magma
The Rock Cycle
• The full cycle does not always take place
due to “shortcuts” or interruptions
The Rock Cycle
Igneous Rock
• “Formed by Fire”
– Slow cooling results in
the formation of large
– Rapid cooling results
in the formation of very
small microscopic
Classifying Igneous Rock
• Texture—Size and arrangement of the
interlocking crystals
– Fine-grained—microscopic crystals
• Example: rhyolite
– Course-grained—able to be seen unaided
• Example: granite
– Porphyritic—large crystals embedded in a matrix of
smaller crystals
• Example: andesite porphyry
– Glassy—rapid cooling of molten rock ejected into the
atmosphere during a volcanic eruption
• Examples: obsidian, pumice
Classifying Igneous Rock
• Mineral Composition
– Depends on the chemical composition of the
magma from which it crystallizes
– Influenced by crystal settling in the magma
(density of the components)
Naming Igneous Rocks
• Basaltic Rocks
– Derived from the first minerals to crystallize
– Rich in iron and magnesium
– Example: basalt
• Granitic rocks
– From the last minerals to crystallize
– Mainly feldspar and quartz
– High silica content
– Example: granite
Naming Igneous Rock
• Rocks may have the same compositions,
but are named differently because of their
different textures.
Sedimentary Rocks
• Compacted and
cemented sediment
– Geologists date the
Earth based on layers
of sediment
– Sediment can contain
– Economically
• Coal, natural gas, oil
• Iron, aluminum,
manganese, fertilizer,
sand and gravel
Classifying Sedimentary Rocks
• Detrital
– Form from solid particles from weathered
– Classified by particle size
– Examples:
Shale (most abundant)
Classifying Sedimentary Rocks
• Chemical
– From material that was once in solution and
precipitates to form sediment
– Common Rocks:
• Limestone (most abundant)
• Travertine
• Microcrystalline quartz
– Chert, flint, jasper, agate
• Evaporites
– Rock salt, gypsum
• Coal
– Lignite, bituminous
Lithification of Sedimentary Rocks
• Compaction
– Weight of overlying material compresses
deeper sediments
• Cementation
– Materials such as calcite, silica, and iron
oxide are carried in solution by water moving
through the pore spaces between particles
Features of Sedimentary Rocks
• Strata or beds—layers of accumulated
• Bedding planes—flat surfaces along which
rocks tend to separate or break
• Fossils
Metamorphic Rocks
• Changed in Form
– From heat, pressure, and chemically active
– Takes place when rock is subjected to
conditions unlike those in which it originally
– Regional metamorphism (mountain building)
and contact metamorphism (molten material
bake surrounding rock)
Three Metamorphic Agents
• Heat
– Most important agent of metamorphism
– Provides energy to drive chemical reactions
that rearrange crystal structures
– Increases with depth
Three Metamorphic Agents
• Pressure
– Increases with depth
– Stress during mountain building
– Rock at great depth is warm and becomes
plastic-like during deformation
Three Metamorphic Agents
• Chemically active fluids
– Water is contained in pore spaces of virtually
every rock
– It acts as a catalyst to help ions migrate to
form crystalline shapes
Metamorphism Changes Texture
• Foliated
– Some minerals under pressure will
recrystallize in an alignment that looks layered
• Examples:
– Shale becomes slate
– Shists—metamorphic rocks that are platy
– Gneiss—metamorphic rocks that are
elongated and granular
Metamorphism Changes Texture
• Nonfoliated
– Some metamorphic rocks are composed of
only one mineral
• Examples:
– Limestone becomes marble
– Quartz sandstone can become quartzite