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Understanding Planet Earth 186-201C, May 2000
STUDY GUIDE FOR MID-TERM EXAM
Regular class time. You must have your ID card for the exam. No books, notes, or calculators will be
allowed.
Understand
 how the Earth was formed (recall the important roles that our position in the solar system and early
melting have had in determining the Earth’s overall composition and internal structure)
 isostasy (give evidence that isostasy occurs)
 how paleomagnetism is recorded in rocks and how it was crucial in developing the "seafloor
spreading" concept
 how the evidence for seafloor spreading and continental drift were combined into the theory of global
plate tectonics
 the relationship between earthquakes, volcanoes, young mountain chains, trenches and plate
boundaries
 the relationship between magma type and plate tectonic setting
 why trenches are curved, and mid-ocean ridges are offset by transform faults
 the different types of seismic waves and details about how they are used to map out the Earth's
interior
Know
 the densities for continental vs. oceanic crust
 the Earth’s interior (5 physical layers and 3 compositional layers)
 the features of volcanoes
 the hazards of volcanoes
 anion/cation definitions
 ionic/covalent bonding
 the physical properties that geologists use to identify minerals (hardness, cleavage, colour, density)
 origin of diamond, special use for quartz in watches, problem of swelling clays, and safety concerns
for asbestos (all of these are to be understood in simple, brief terms)
Practice drawing and labeling the following
 a cross-section through a mid-ocean ridge with a magma chamber
 transform boundaries offsetting a mid-ocean ridge as seen from above
 a cross-section through each of the 2 different types of subduction zones (include igneous features,
like upwelling magma and volcanoes)
 a cross-section of the Benioff Zone (remember that from above [“plan view”] there will be a
“shallow” to “deep” progression moving away from the trench, and that the earthquake pattern will
parallel the trench)
 the 4 stages of intracontinental rifting (uplift – rift valley – linear sea – new ocean); also show the
rifting in "plan view" by drawing what would happen at each stage along the arms of a triple point
junction.
 the supercontinent cycle
 pressure-temperature graphs for dry and wet partial melting
Be able to give igneous (magma sources and types, etc.) and general seismic characteristics for all types
of plate boundaries as well as geographic examples (e.g., Japan, Iceland, Andes, San Andreas Fault,
Understanding Planet Earth 186-201C, May 2000
Himalayas, Atlantic mid-ocean ridge, African rift system) for all types of plate boundaries. Combining
geography and plate tectonics isn’t very difficult when you remember well-known features about certain
places:
 the Himalayan mountains have the highest land elevation in the world and there are no active
volcanoes – this fits best with continental collision where one continental plate is trying to move
under another building up great thickness, and the subducting plate breaks off and consequently there
is no melting to form volcanoes
 Japan and the western coast of South America are regions that experience strong earthquakes and
violent volcanic eruptions, so they must be located along subduction zones – Japan is an island, so
the subduction type must be ocean-ocean (volcanic island arc), whereas the Andes are bounded by a
continent to the east and an ocean to the west, so the subduction type must be ocean-continent
 the East African rift is a valley system within the African continent, so it must be an example of
divergence within a continental plate
 Iceland is in the middle of the Atlantic Ocean and the only plate boundary in the Atlantic is the midocean ridge
 The San Andreas fault zone experiences strong earthquakes, but no volcanic activity and no rift
valleys – it must be a transform (sliding) plate boundary
Practice making charts for the following:
 Bowen’s reaction series
 the classification for silicate minerals based on arrangement of silica tetrahedra (can you also sketch
the silica tetrahedron?)
Could you fill in the blanks for the following? (check the website for each of these – should be posted by
Friday)
 the rock cycle
 a table showing the relationship between magma types and viscosity, silica (SiO2) content,
polymerization, ease of gas escape, nature of eruption, rock type… (also see website)
 the different properties of minerals and their underlying causes – give examples for each
You do NOT have to know:
 Figure 4.6 (the chart showing mineral contents of different rocks) because if you remember Bowen’s
crystallization series, then you know the basic mineralogy of felsic and mafic rock types (and by the
way, I would ignore 4.7 – I find it confusingly presented and not really necessary)
 anything about the minerals calcite (a carbonate mineral) or hematite (an oxide mineral) or pyrite (a
sulfide mineral)… at least not yet!
Typical Mistakes:
 not answering all aspects of a question
 not properly labeling diagrams
 cross-sections that do not extend through the lithosphere or even the crust
 confusing the terms “lithosphere” with “crust”
 essays: sentences that say nothing (blah blah blah), illogical thought sequence, absence of
introduction and conclusion, omission of basic definitions … all these typically reflect the lack of a
proper outline, so take a few minutes to write one down before starting.