Geos 100 Fall 2011 – Midterm #2 Study Guide
You are allowed an 8”x11” 2 sided review sheet during the test.
The test will be in the 1st hour of the lab period followed by a new Structural
Geology Lab 9.
Be prepared to be tested on these topics by short illustrated essays or multiple choice
questions. Be able to understand the concepts and use the key vocabulary for each
topic. Keep this review sheet for review for the final exam as it is cumulative!
Format:
60-70 points: Multiple choice, matching or fill in the blank for terms and definitions
or processes and simple concepts.
Examples:
1. The sediment expected for a steep fast flowing mountain stream is ___
a. oolite
b. conglomerate
c. chert
d. shale
2. The igneous source rock for diamonds is _______.
a. obsidian
b. granodiorite
c. kimberlite d. porphyritic andesite
3. A very low geothermal gradient and _____ pressure is characteristic for
_______ facies metamorphism.
a. high, blueschist b. low, granulite c. intermediate, hornfels d. low, eclogite
40 – 30 points: Essays and Drawing diagrams, relating complicated cycles,
processes, earth structures, tectonic settings. Comprising 10 or more items each to
be discussed in proper form and drawn and labeled.
Igneous Rocks and Processes: Chapters 3, 4 in Text and 5 in Lab Book
Text Chapter 3 (Igneous Rocks, Magmas, Intrusive Activity)
1. Magmas & silicate melts: (Densities Temperatures Silica Contents
Viscosities)
2. Magma Origin (decompression, partial melting, heating, fluxing)
3. Lavas and Pyroclastics
4. Tectonic Settings (Divergent Convergent, Within Plate)
5. Compositional Types: Basalt from Peridotite via few percent partial melting,
Rhyolite from Gabbro-Granodiorite via few percent partial melting or 90%
crystallization and differentiation
6. (Mafic=Basalt, Intermediate=Andesite, Felsic=Rhyolite), Abundance,
Textures, (Phaneritic Porphyritic Aphanitic. As in Pegmatite Granite Crystal
Tuff Obsidian)
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7. Classification by mineralogy & texture, Bowen’s Reaction Series
discontinuous: (OPABKMQ (Oh Please Amy Baby Kiss Me Quick!) &
Continuous (Anorthite  Albite) with falling temperature
8. Magma modification & evolution (source partial melting Upper Mantle
peridotite  basalt and Lower crust amphibolite/gabbro) & magma mixing,
differentiation (crystal fractionation) and contamination)
9. Intrusive Bodies (Batholiths, Stocks Plutons Plugs Dykes Sills Laccoliths
Pipes Necks etc.)
10. Ring of fire batholiths, porphyry Cu-Au deposits, Black smokers and VMS
(volcanogenic massive sulfide) deposits.
11. Which of the following were once magmas and if not what were they?:
Andesite, Lava, Chromite, Tuff, Granite, Anorthosite, Kimberlite)
12. What is an Ophiolite succession and what does it show?
Text Chapter 4 (Volcanism & Volcanoes)
1. Volatiles and outgassing (H2O, CO2, N2, SO2, H2S, SO2, He, Ar)
2. Effusive vs Explosive, Eruption Styles (hawaiian, strombolian, vucanian,
plinian)
3. Volcano Edifice Types (plateaus, shield, stratovolcano, caldera, cinder cone,
diatreme-maar)
4. Types of lava and magma and abundance vs setting (kimberlite, basalt,
andestite, rhyolite, carbonatite, apatite-magnetite)
5. Pahoehoe, aa, volcanic breccias, pyroclastics/tuffs, craters, calderas, nuee
ardentes (welded tuffs), domes, tuyas, jokulhaups
6. Plate margin and intraplate volcanoes, examples of each
7. Archean komatiities
8. Volcanic hazards: explosive felsic volcanism, Plinian column collapse, lahars
and mudflows, landslides, caldera collapse
9. Giant caldera eruptions (Super colossal): Krakatoa, Tambora, Katmai,
Mazama.
10. Cascades volcanoes: Mt. St Helens, Mt. Baker, Garibaldi Meagher, Cayley.
11. Hotspot volcanoes: Iceland, Hawaii, Azores, Kerguelen, Kilimanjaro,
Yellowstone.
12. Flood basalt volcanism: Columbia River Plateau (Miocene), Deccan Traps
(K/T boundary), Siberian Traps etc.
13. Climate effects, albedo, atmospheric acidification.
14. Volcanism on other planets: Venus, Io, Europa active; Olympus Mons,
Lunar Mare extinct (Precambrian).
Chapters 5 & 9: External processes and products: Weathering, Mass Wasting, Soils
and Sediments
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1. What are the 2 major types of weathering and give 3 examples of each
process.
2. How are erosion and mass wasting different or similar processes?
3. What are the principal soil horizons and what chemical changes occur in
each?
4. What physical or biological processes result in mechanical weathering (name
4)?
5. What factors speed up mechanical weathering?
6. Compare and contrast the dissolved versus insoluble products of the
chemical weathering of feldspars versus ferromagnesian minerals.
7. What soil environments would generate: regolith, loess, caliche, laterite,
podsol, pedalfer and how do these soils differ physically and chemically?
8. What are the 3 major processes involved in all types of chemical weathering
and what environmental factors control the rates at which they occur?
9. What are 3 sources of acidity that contribute to chemical weathering?
10. What is the difference between oxidation and dissolution?
11. What are the sources and sinks in the global carbon cycle and how do these
processes have feedback to climate change?
12. Compare and contrast the chemical weathering of feldspar and a
ferromagnesian silicate mineral like pyroxene or amphibole in terms of
products.
13. What factors speed up chemical weathering?
14. What effect does rock type have on mechanical and chemical weathering?
15. What are the sources and sinks in the global carbon cycle?
16. What are some of the geological events that can trigger sudden mass
wasting?
17. How might global warming affect mass wasting processes in Canada’s alpine
& arctic regions?
18. How do mass wasting events rank among geological hazards?
19. What triggered the mass wasting events at Nevado del Ruiz, YungayHuascaran, Turnagin Heights and Vaiont and which disaster claimed the
most lives?
Vocabulary: Airborne avalanche, Angle of repose, AOBC soil horizons, Caliche,
Chemical weathering, Creep, Earthflow, Eluviation, Exfoliation, Frost wedging,
Erosion, Hardpan, Hydrolysis, Jokulhlaup, Karst, Laterite, Mass wasting,
Mechanical weathering, Oxidation, Permafrost, Regolith, Rockslide, Sheeting,
Slump, Solifluction, Thermokarst
Ch7: Metamorphism and Metamorphic Rocks
1. How do various metamorphic rock types vary with respect to metamorphic
grade and how do we tell those grades apart by grain size, texture and
mineralogy?
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2. Compare and contrast the mineralogical and textural changes that occur
during progressive metamorphism of a quartz rich sandstone, a limestone, a
shale and a basalt.
3. What are the 4 principal factors in causing metamorphic changes?
4. What are the differences in brittle versus ductile deformation, where would
each occur and what kinds of metamorphic rock fabrics result from each
style?
5. What are the 2 principal metamorphic fluids, what is their dominant effect
on metamorphism and give examples of mineral reactions involving each
one?
6. What effect does prograde metamorphism have on fluids and why is this so?
7. What are the mineral facies names for successive metamorphic grades and
what temperature regimes are implied by each index mineral?
8. What conditions would cause a mudstone to change to a hornfels versus a
schist and how could you tell the 2 metamorphic products apart?
9. How would the regional metamorphism of subducted ocean crust differ from
the regional metamorphism of sediments on a continental margin? (what
special facies occur only in rocks of this composition?)
10. How do skarns and hydrothermal metamorphic rocks differ from regional or
contact metamorphic rocks in texture and composition?
11. Where would you expect to find skarns and hornfels and how extensive are
these types of metamorphic rocks?
12. What sequence of rock types would be found with progressive dynamic
metamorphism (strain not P,T changes) in a fault zone?
13. Compare and contrast 4 types of metamorphism and discuss where each type
might occur and what rock types would result? (burial, regional, contact,
dynamic (cataclastic))
14. What did the Grenville orogen have to do with metamorphism and with the
plate tectonic cycle?
15. What are tektites and migmatites and where would each form?
16. What is the cause of paired linear metamorphic belts and where do they
form?
17. How would you recognize or find an isograd in a metamorphic map area?
18. Where/what are the oldest dated metamorphic rocks in Canada; in the
world?
19. Who were Barrow (regional metamorphic facies), Eskola (mineral isograds)
and Kuno (paired metamorphic belts) and what contributions did each make
to metamorphic geology?
20. While rocks need to be buried deeply or subducted to generate higher
pressure and temperature minerals, why do these new high grade minerals
generally not revert to lower P,T forms upon uplift and erosion?
21. What types of gems or ore deposits are associated with metamorphic rocks?
22. Where does regional metamorphism occur and how do the rocks differ from
their parents?
23. What is dynamic metamorphism and name 2 different settings where this
occurs?
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Vocabulary: Amphibolite, Aureole, Aluminosilicate polymorphs (Andalusite,
Kyanite, Sillimanite), Blueschist, Boudins, Cataclastic, Contact, Dehydration,
Dynamothermal, Eclogite, Foliation, Forearc metamorphism, Geothermal gradient,
Gneiss, Gouge, Granoblastic, Granulite, Greenschist, Hornfels, Hydrothermal,
Index mineral, Isograd, Migmatite, Mylonite, Parent rock (protolith), Phyllite,
Poilikitic, Porphyroblast, Prograde, Retrograde, Rolled garnets, Roof pendant,
Schistosity, Shattercone, Shield, Skarn, Slaty cleavage, Tectite, Zeolite facies
Ch. 8 Relative and Absolute Dating and Geological Time:
1. Why does the geological time scale have time divisions of unequal length and
place names for its successive intervals, eg. Devonian, Mississippian,
Jurassic?
2. Why was the Precambrian so long?
3. What is Steno’s law of superposition?
4. What are the 3 types of unconformity and relative amount of missing time
represented by each one?
5. Which rock types are most useful for determining the relative sense of earth
history and past environments?
6. Name 2 massive extinction events and discuss the theories for their causes?
7. What kinds of materials can be radiometrically dated?
8. What does the absolute age of a mineral indicate?
9. How does radiocarbon form and how does it decay and are there any other
elements or particles involved?
10. If the half-life of 235U is 713 Ma, how much daughter 207Pb would you expect
to form in 178 Ma relative to the initial amount of parent uranuim?
11. What is significant about 3.9 Ga in the inner solar system?
Vocabulary: Alpha particle, Angular unconformity, Archean, Beta particle, Contact
relationship, Contamination, Correlation dating (strata, fossils, paleomagnetism,
stable isotopes, fallout), Cross cutting, Daughter isotope (radiogenic isotope),
Dendrochronology (wiggle matching), Disconformity, Era. Eon, Fission track, Fossil
(faunal) assemblage and succession, Gamma ray, Geologic time scale, Gradualism,
Half-life, Hiatus, Imbrium era, Inclusion, Index (zone) fossil, Massive extinction,
Nonconformity, Parent isotope (radioisotope), Period, Radiometric decay equation
(Afinal = Ainitial e- αt ), Radon, Reworking, Superposition, Unconformity, Zircon
Essays: There will probably be 3-5 essays covering:
1. Soils, weathering, sediments or facies, causes of transgressions & regressions
2. Volcanoes, plutons, igneous rocks, Bowen’s reaction series, magma
properties, tectonic environments for magma formation
3. Metamorphic index minerals, metamorphic facies, types of metamorphism,
tectonic settings for metamorphism
4. Mineral and other natural resources associated with the 3 main rock types.
5. Relative geological time, radiometric dating
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