Study guide
Chapter 1- Introduction
 Layers of the earth by physical properties – e.g. lithosphere, asthenosphere
 Difference between ocean crust and continental crust
 The rock cycle
Chapter 2 - Minerals
 The 5 naturally defining characteristic of minerals: naturally occurring, inorganic, solid, definite
chemical structure, orderly crystalline structure
 Important Properties of Minerals esp. hardness, luster, cleavage
 Silicate Minerals and the Silicate ion (SiO-4 ), their common building block
o ferromagnesian minerals (olivine, pyroxene, amphibole, biotite mica)
o nonferromagnesian minerals (feldspar, muscovite mica, quartz)
 Non-silicate Minerals
o calcite (carbonate mineral group) - fizzes when in contact with acid
o gypsum (sulfate mineral group) – scratches with fingernail
 identification of the common igneous-rock-forming silicate minerals
Chapter 3 - Igneous Rocks
 Difference between magma and lava
 Origin of Igneous Rocks:
o Plutonic, or Intrusive (remember Pluto, Lord of the Underworld!) - slow cooling
underground
o Volcanic, or Extrusive - fast cooling above ground
 Classification by texture: Dependent on origin
o phaneritic - large crystals - plutonic
o aphanitic - small crystals - volcanic
o porphyritic - large crystals embedded in a fine-grained matrix - usually volcanic
o glassy - cooled too fast to form crystals - volcanic
o pyroclastic - formed from volcanic ash or pieces of lava- volcanic
o vesicular – filled with voids from escaping gas bubbles
 Classification by mineral content: dependent on mineral content of magma
o ultramafic (composed of ferromagnesian minerals)
o mafic or basaltic (composed of ferromagnesian minerals and Ca plagioclase)
o intermediate or andesitic (composed of ferromagnesian minerals, Ca-Na plagioclase and
non-ferromagnesian minerals
o felsic or granitic (composed primarily of non-ferromagnesian minerals; less than 15%
ferromagnesian.
 Igneous rocks identification
 Generating magma from solid rock
o Increase in temperature
o Decompression melting
o Addition of water
 Partial Melting - production of a magma with a higher silica content than the parent rock
o Silica-rich (felsic) magma starts to melt at about 750deg C in a near-surface environment
o Basaltic (mafic) magma starts to melt at about 1000 deg C in a near-surface environment
Chapter 4 - Igneous Activity
 Viscosity – determines the nature of volcanic activity and what influences it:
o temperature (increase in temp. decreases viscosity)
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o
presence of dissolved gas, usually decreases viscosity, although expansion of water vapor
causes a more pyroclastic, explosive eruption)
o (most important) - increasing silica content of magma increases viscosity
 Volcanic structures
o Shield volcano - composed primarily of fluid basaltic lava flows-large in area, elevation,
very gentle slope. Ex: Hawaii
o Cinder cones - composed primarily of volcanic ash and /or other pyroclastic material,
usually granitic in composition, example Sunset Crater, Arizona
o Composite cones or stratovolcanoes - composed of alternating layers of lava flows and
pyroclastics, usually andesitic in composition. Example: Ring of Fire volcanoes (Mt. St.
Helens)
o Fissure eruptions - volcanic activity that does not come from a central vent. Example:
Columbia Plateau Basalt Flows
o Calderas
 Lava types: aa, pahoehoe
 Hawaiian-type volcanoes vs Ring of Fire volcanoes: difference in eruption style and volcanic
structure
 Intrusive IgneousActivity: Pluton – structure that results from emplacement of igneous materials at
depth.
o Exposed by uplift and subsequent erosion of overlying rocks.
o Classified by orientation to host rock, either concordant (parallel, sill) or discordant (cuts
across, dike)
o Batholith - a large intrusive igneous body with an exposure of more than 100 sq. km
 Igneous Activity distribution
o Igneous activity at subduction zones: Ring of Fire volcanos
o Igneous activity at Spreading Centers: Iceland, East Africa
o Intraplate Igneous Activity (hot spots): Hawaii, Yellowstone
Chapter 6- Sedimentary Rocks
 Detrital - formed from the solid products of physical and chemical weathering.
Classified by grain size: gravels (conglomerate), sand (sandstone), silt (siltstone), clay (shale, mudstone)
Above categories subclassified by mineral composition
 Chemical - formed from chemical sediments, from dissolved products of chemical weathering,
and classified by mineral composition:
o Biochemical: formed from minerals that have a biochemical origin (e.g most limestone)
o plant remains (coal)
 Lithification – set of processes that turn unconsolidated sediment into sedimentary rock
o Compaction
o Cementation – iron oxide, silica, calcite
 Environments of Deposition – determines the type of sediment, and therefore sedimentary rock
 Sedimentary Rock identification
Metamorphic Rocks - Chapter 7
 Metamorphic Rocks - formed by high amounts of heat and pressure that occur at depth due to
tectonic activity
 Agents of Metamorphism: heat, pressure, chemically active groundwater
 Metamorphic environments (in order of importance)
o Regional (mountain-building)
o Contact or Thermal
o Hydrothermal
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
Changes in Rocks due to Metamorphism
o Recrystallization of existing minerals, especially into larger crystals;
o Mineralogical Change as of new minerals develop some of the old ones disappear; and
o Foliation – Reorientation of existing mineral crystals and growth of new ones in parallel
or nearly parallel planes, due to differential pressure.
 Foliation (from least to most intense)
o slaty cleavage: mica crystals, not visible to the naked eye, become aligned so they are
parallel (applies to slates and phyllites)
o schistosity: mica or hornblende crystals grow big enough to give the rock a platy or
“glittery appearance”
o gneissic banding: Mineral migration occurs and dark and light silicate minerals separate,
giving the rock a banded appearance
 Common metamorphic rocks: slate, phyllite,schist, gneiss, quartzite, marble
Chapter 14 - Earthquakes
 Mechanism of earthquake
o why they tend to occur at plate boundaries
o focus, epicenter and how related to faults
o elastic deformation, elastic rebound
 Earthquake Magnitude:
o measures energy released
o the same value for a particular earthquake, regardless of where measure
o logarithmic : Richter Scale, Moment Magnitude Scale
Seismology - study of earthquake waves
o
p-waves, compressional - particle motion parallel to direction of wave travel
o
s-waves, shear - particle motion perpendicular to direction of wave travel
o
Epicenter location using p-waves and s-waves
Chapter 15, Plate Tectonics
 Alfred Wegener and Continental Drift
o fit of the continents
o similarities in rock type and structure
o fossil evidence
o paleoclimatic (glacial) evidence
o Wegener’s inability to propose a mechanism for continental drift
 tectonic plate boundaries and geographic examples of each
o divergent - sea floor spreading
o convergent – subduction oceanic-continental, oceanic-oceanic
o convergent – continental collision
o features associated with each of the above (trenches, volcanoes , earthquakes etc.)
o geographic example of each
Chapter 17 – Mountain Building
 Rock deformation
 Brittle deformation (fractures, faulting)
 Elastic deformation
 Ductile (plastic) deformation (folding)
 Folds - mostly caused by compressional stress
 Anticlines – oldest strata found in center after erosion
 Synclines – youngest strata found in center after erosion
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 plunging folds – compressed at an angle relative to horizontal plane.
Faults-fractures in the crust along which movement has occurred.
 Dip-slip- Primarily vertical movement.
 Normal fault (Tensional) - hanging wall drops down relative to foot wall
 Reverse fault (Compressional) - foot wall drops relative to hanging wall
 Thrust fault (Compressional) - low angle reverse fault
 Strike-slip- Primarily horizontal movement. San Andreas Fault System (Box 17.1)
 Mountain Types
 Volcanic (studied in Chapter 4)
 Fault-Block mountains- associated with tensional stress on the crust. Horst and Graben
topography
 Folded (complex) mountains - major mountain chains, such as Alps, Himalayas, Urals, etc.,
caused by folding from convergence.
 Types of (mountain belts)
 Andean-type convergence (continental-oceanic or oceanic-oceanic subduction)
 Volcanic Mountains (which may erode to expose intrusive core)
 Accretionary Wedge
 California’s Sierras and Coastal Ranges as examples
 Himalayan-type convergence (continental collision): Urals, Appalachians, Alps and (or
course) Himalayas are examples
Chapter 18 Geologic Time
Relative Dating - Key Principles

Law of Superposition

Principle of Original Horizontality

Principle of Cross-Cutting Relationships

Inclusions

Unconformities,

Correlation: Using relative dating techniques to date a sequence of sedimentary strata and
structures.

Use of relative dating techniques to date a cross-section
Absolute Dating with Radioactivity

Radioactivity – an unstable element decays, by gaining or losing nuclear particles, and becomes
another, more stable element

Half life

Carbon-14 dating
 how it forms, what it decays into
 how we use it to measure absolute ages
 why it is not useful for inorganic materials
 why it is not as useful in dating material older than 50,000 years
 how we correct for variations in C-14 levels in the atmosphere

Other materials used for Radioactive Dating, e.g. uranium, Potassium and their use in dating
older materials.

Uranium and its use in establishing the age of the Earth.
Geologic Time Scale
 Paleozoic, Mesozoic, Cenozoic Eras
 Eras subdivided into periods, and (in later periods) epochs.
 The time boundaries between the eras represent times of mass extinctions and the evolution of
new species

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