Download - Catalyst

Final Exam Review
Igneous Processes (Part 2)
Volcanoes Types (Understand how and where they form)
-shield volcanoes (oceanic hot spots)
-strato volcanoes (subduction zones)
-pyroclastic volcanoes (cinder cones)
-Fisure eruptions (plateau basalts)
-Eruptions under water (pillow basalts)
Plutons (magma body crystallizes underground)
Large plutons- batholith, stock, laccolith and lopolith
Small plutons- dikes, sills and necks (understand how they form and are classified).
Volcanic Hazards
Effusive eruptions (Iceland, Hawaii)
Phreatic eruptions (subduction zone, St. Pierre, Pompeii)
-pyroclastic eruptions
-lahars
Pacific Northwest volcanoes: Mt. Rainier and Mt. St. Helens
Assessing volcanic hazards (recurrence intervals)
Weathering
Weathering is the chemical alteration and physical breakdown of rock material during exposure
to the air, moisture, and organic matter.
Mechanical Weathering:
Forms of mechanical weathering:
-development of joints
-crystal growth (salts)
-frost wedging/ freeze thaw
-effects of heat (spalling and thermal expansion/ contraction)
-bioturbation (root penetration and enlarging joint fractures in rock)
Chemical Weathering
Common Chemical Weathering Reactions
-carbonation
-hydrolysis
-oxidation
-dissolution
Weathering Effects on Common Rocks
-Concentration of Stable Minerals
-Weathering Rinds
-Exfoliation and Spheroidal Weathering
Factors That Influence Weathering:
Climate
Organisms
Relief
Parent Material
Time
Soils
Processes of Soil Formation
-Eluviation (removal)
-Illuviation (accumulation)
-Translocation (physical movement of material through the soil profile)
-Transformation (in situ chemical alteration of minerals within soil profile)
Factors of Soil formation (Clorpt)
Cl imate
O rganisms
R elief
P arent Material
T ime
Sedimentary Rocks
Sediment to Sedimentary Rock
-accumulation
-compaction
-cementation
Classifying Sedimentary Rocks: sedimentary rocks are classified according to the size, shape,
and composition of their constituent particles.
Clastic Sedimentary Rocks: accumulated particles of broken rock or skeletal remains of dead
organisms.
-conglomerate, sandstone, siltstone, mudstone (shale)
-sedimentary breccia, coquina
Chemical Sedimentary Rocks: formed by precipitation of minerals from solution in water.
-limestone, dolostone, rock salt
Diagenesis: refers to changes that affect sediment after its initial deposition.
-compaction, cementation, recrystalization, oxidation, reduction
Sedimentary Structures (Features)
-stratification
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parallel strata
cross strata
-rounding
-sorting
-Arrangements of particles within a stratum
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uniform layers
graded bedding
-Structure and Bedding within Sedimentary Rocks
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ripple marks
mud cracks
deltaic structures (bottomset, foreset and topset beds)
graded bedding (turbidite sequences)
-Fossils
Stratigraphy and Geologic Time
I) Principal of uniformitarianism (James Hutton, 1785)
-"the present is the key to the past"
-The laws of nature do not change with time.
-The Earth has evolved by uniform, gradual processes over an immense span of time.
II) Relative Dating
-determining the chronologic order of a sequence of events
Relative dating is accomplished by applying the principles of stratigraphy
A) Principles of Stratigraphy
1) the principle of superposition (Nicolaus Steno, 1669)
-we must assume that:
i) rock layers were horizontal when they were deposited.
ii) the rocks have not been so severely deformed that the beds are overturned.
2) the principle of faunal succession
3) the principle of crosscutting relations
4) the principle of inclusions
B) Breaks in the Stratigraphic Record (Unconformities and hiatuses)
-An unconformity is a substantial break or gap in a stratigraphic sequence that marks the absence
of part of the rock record
-A hiatus is the lapse in time recorded by an unconformity
1) Angular unconformity
2) Disconformity
3) Nonconformity
III) The Geologic Time Scale
-using the principles of superposition and faunal succession, geologists have determined the
chronologic sequence of rocks throughout broad regions of the world and have constructed a
standard geologic time scale.
-Rock units are distinguished from each other by major changes in rock type, unconformities, or
abrupt vertical changes in the fossil groups they contain.
-Divided into geologic time units which are used worldwide: eons, eras, periods, and epochs.
You do not need to memorize the geologic time scale. Understand how the major subdivisions
were defined (i.e., using evolutionary changes in the fossil record to define subdivisions).
Radiometric Dating (Numerical Dating)
I) Chemistry Review:
II) Radiometric Dating
A) Natural Radioactivity
-Some chemical elements composing the Earth are radioactive and therefore unstable.
-In radioactive elements, the unstable nucleus is spontaneously transformed to a more stable
isotope of the same chemical element or a stable nucleus of a different chemical element.
(Radioactive decay).
-parent vs daughter product
B) Rates of Decay
The rate of decay of the unstable parent radionuclide decreases exponentially (it is not linear).
The rate of decay is defined by half-lives (see Fig. 6.14 in text).
Different radionuclides have different half-lives and therefore different effective dating ranges.
Assumptions of radiometric dating:
1) The rock or mineral must be a "closed system."
2) We must be able to accurately determine a value for the initial daughter atoms if they were
present in mineral or rock sample being dated.
3) The value of the decay constant (λ) must be known accurately.
4) The measurements of the parent and daughter atoms must be accurate and representative of
the rock or mineral to be dated.
Isotopic Dating Systems (We discussed the K-Ar system in lecture).
1) Potassium-Argon (40K/40Ar) Dating T1/2 = 1.3 b.y.
3) Radiocarbon (14C) Dating T1/2 = 5,730 years (Read the section in your textbook on
radiocarbon dating. I will have two questions on the final exam from this reading. You are not
responsible for the other dating techniques we did not discuss).
Metamorphic Rocks and Metamorphism (use your laboratory reading to study)
Contact vs regional metamorphism
Non-foliated (heat) vs foliated metamorphic rocks (heat and pressure)
Deformation of Rock and Geologic Structures
How is rock deformed?
Stress and strain
Elastic deformation
Deformation by brittle fracture
Ductile Deformation
Ductile Deformation versus Brittle Fracture
Controlling Factors
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temperature
confining pressure
time
strain rate
composition
Evidence of Deformation (Geologic Structures)
Brittle Fracture
Faulting
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Normal Faults
Reverse and Thrust Faults
Strike-slip
Transform faults
Geologic Evidence of Movement along Faults
Ductile deformation (bending of rocks)
Measuring folded rock
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strike and dip
Classifying folds
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monoclines
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anticlines
synclines
plunging folds
complex folds
Seismology, Earthquakes, and Tectonic Hazards
Earthquakes
What are they?
Origin of Earthquakes
Seismic Waves
Body waves versus surface waves
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P-waves (compressional)
S-waves (shear)
surface waves
Location of the Epicenter
Magnitude of Earthquakes
Richter Magnitude scale
World Distribution of Earthquakes
Earthquakes and plate tectonics
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Seismicity at divergent plate boundaries
Seismicity at convergent plate boundaries
Intraplate seismicity
Seismicity in the Pacific Northwest
Where do earthquakes occur?
-within the North American plate
-within the Juan de Fuca plate
-rupture along the subduction zone