PHYSICAL GEOGRAPHY SPHERES
GEOG 1010
Atmosphere
Introduction to Geography
Hydrosphere
THE ROCK CYCLE
Lithosphere
Magnetosphere (remember last class)
Cryosphere
Dr. Hester Jiskoot
Biosphere
LECTURE STRUCTURE
1. What is a rock?
2. The rock cycle
3. Elements and minerals
4. Rock types & rock forming processes
5. What is YOUR rock?
See also “Introductory Geography” Chapter 9 pp. 334-345
WHAT IS A ROCK?
THE ROCK CYCLE, main rock types and their rock forming processes
Sedimentary
Weathering
Transport
Deposition
Cementation
Compaction
A solid assemblage of minerals bound
together or a mass of a single mineral
Formed or reformed during 1 of 3
rock-forming processes
Igneous
Impermanent, but ‘longer-lived’ than you & me
Melting
Cooling
Crystallisation
Metamorphic
Heat
and/or
Pressure
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Element
Symbol
% Weight
Oxygen
O
Silicon
Si
Aluminum
Al
8.1
Iron
Fe
5.0
Calcium
Ca
3.6
Sodium
Na
2.8
Potassium
K
2.6
Magnesium
Mg
2.1
46.6
SiO2-Silica
All others
27.7
1.5
Continental igneous: SiAl
Oceanic igneous:
SiMg
A) SILICATE MINERALS
• alumino-silicate (felsic) minerals Æ light
quartz, feldspar
• ferromagnesian-silicate (mafic) minerals Æ dark
olivine, pyroxene
B) CARBONATE MINERALS
calcite (calcium carbonate)
C) CLAY MINERALS
phyllosilicates
Æ SIAL Æ felsic
Æ SIMAÆ mafic
ROCK TYPE
SUBTYPE
EXAMPLES
Igneous
Intrusive
granite
Extrusive
rhyolite
gabbro
basalt
Metamorphic
Minerals are inorganic element assemblages
Foliated
Igneous or volcanic processes
*** Magma cools down ***
Slow
How fast?
gneiss
schist
Non-foliated quartzite
marble
Sedimentary
Clastic
Crystals have time to form
Fast
Crystals have NO time to form
Intrusive
Plutonic rocks
Extrusive
Lava
Where?
sandstone
shale
Chemical
limestone
Biogenic
coal
Rock forming process = crystallisation
Volcanic rock types
GRANITE
BASALT
Fig 9.9, p339 of your book
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SANDSTONE
Sedimentary processes
Small rock particles are eroded/dissolved,
transported & deposited as sediments
Clastic sediments
= mineral particles
Non-clastic sediments = chemical/organic precipitates or evaporites
Rock forming process = Lithification
Lithification = Diagenesis = Cementation, Compaction & Hardening
Layering = Stratification
SHALE
LIMESTONE
Lithified Ca+-rich skeletons of sea animals
Easily soluble in water
COAL
Peat Æ Lignite Æ Bituminous Æ Anthracite
Increasing degree of lithification and metamorphosis
Metamorphic processes
*** Rocks deform under heat/pressure ***
Igneous rocks
Sedimentary rocks
Change physically or chemically under heat/pressure
GNEISS
Metamorphic rocks
Makes hard compact rocks
Foliated
Non-foliated
Rock forming
processprocess
= metamorphism
Rock forming
= Metamorphosis
MARBLE
How to make a GNEISS…
http://seis.natsci.csulb.edu/bperry/metarock/METAMORPHISM.htm
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ROCK TYPE
SUBTYPE
EXAMPLES
Igneous
Intrusive
granite
Extrusive
rhyolite
DISTRIBUTION OF
gabbro
basalt
Metamorphic
Foliated
gneiss
schist
Non-foliated quartzite
marble
Sedimentary
Clastic
sandstone
Chemical
limestone
Biogenic
coal
shale
What is YOUR rock?
COLD
MEANINGFUL GRANULAR
POWERFULLIGHT DARK
LAYERED ?
DULL
SHINY
?
HEAVY LIGHT
SOFT
BEAUTIFUL
HARD
?
WARM
SMOOTH
ROUGH
COLOURFUL
?
USEFUL
Which type is your rock?
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