Introduction:

Scientific Method
Key Words: hypothesis, theory, paradigm

• What are the four "steps" in the scientific method?

2. develop a working hypothesis

3. construct experiments to validate the hypothesis

4. either accept, reject, or modify the hypothesis based on this testing

• Is the scientific method the only way scientists make discoveries and solve problems?  Explain.

In class we discussed two different meaning of the word "environment".  Explain how they differ.

An environment is defined as everything that surrounds and influences an organism or item.  For example, if we wanted to discuss the environment that a fossilized marine organism once lived in, we might say something about the energy of the environment, the water depth and water temperature, the types of sediment present, etc. Today, we often use the term "environment" to describe the relationship between people and the natural environment.  For example, when we talk about protecting the environment, we are usually talking about preserving nature in some way, such as protecting wetlands, old growth forests, endangered species, water supplies, etc. from destruction and/or pollution.

• What is the difference between a renewable and non-renewable resource?  Give an example of each.

Earth's Interior
Key words: compositional layers (crust, mantle, core), behavioral layers (lithosphere, asthenosphere, lower mantle, outer core, inner core)

Plate tectonics

Also refer to: In-class plate boundary labeling activity, Earth's Lucky Geology on-line article

• Who originally proposed the idea of continental drift? Alfred Wegener
• What four lines of evidence did he provide to support his idea? 
  
• 1. the continents fit together like a jigsaw puzzle
  2. rock types and structures (mountain ranges) on different continents match
  3. fossils on different continents match
  4. evidence of past climates (glaciation) on different continents match
• How does today's theory of plate tectonics differ from the theory of continental drift? Wegener's theory suggested that the continents "drifted" through the oceans.  Plate tectonics theory describes how both continental and oceanic plates move.

• Types of lithospheric plate boundaries: 
• divergent 
• What is occurring at this type of boundary? Two plates are moving away from each other. 
• What is an ocean ridge? An elevated area on the ocean floor.  Why does it form here? As the two lithospheric plates pull apart, the pressure on the underlying mantle is decreased.  This allows for the mantle to melt (via decompression melting), rise, erupt and cool to form new oceanic crust.  When the new crust is hot it has a greater volume and is less dense than the surrounding cooler rocks. Thus it creates a ridge (also see pages 195-198) in book.  This is also sometimes referred to as a spreading ridge or an oceanic spreading ridge.
  
• A divergent boundary makes new lithosphere (or crust).
• List one specific example of this boundary.  (Hint: See the map we labeled in class.) Mid-Atlantic Ridge (through Iceland), Red Sea.
• convergent
• oceanic-continental
• oceanic-oceanic 
• continental-continental
• What is occurring at each of the above three types of convergent boundaries?  Which plate subducts?  Why?  At convergent plate boundaries two plates collide, and lithopshere is consumed.  At an oceanic-continental boundary the oceanic plate will subduct because it is more dense.  At an oceanic-oceanic boundary one of the dense oceanic plates will subduct (usually the older one).  At a continental-continental boundary, both plates are not dense enough to subduct, thus material is pushed upwards.

• What is a subduction zone? A long, narrow zone where one lithospheric plate subducts or descends beneath another.  It is also characterized by a deep ocean trench and either a continental volcanic arc or and island arc.
• What is a deep ocean trench?  Where is it found? A narrow, elongated depression on the floor of the ocean, found essentially parallel to a subduction zone.
• A convergent boundary destroys (or consumes) crust.
• List one specific example of this boundary.  (Hint: See the map we labeled in class.) 
• O-C => Peru-Chile Trench/Andes Mountains along western side of S. America, Juan de Fuca and N.American Plate boundary
• O-O => Aleutian Islands, Japan, near Mariana Trench
• C-C => Himalayas (Indian and Eurasian plate collision)
  
• transform
• What is occurring at this type of boundary? Two plates are sliding past one another.  Lithosphere is neither created or consumed.
• List one specific example of this boundary.  (Hint: See the map we labeled in class.) San Andreas Fault, CA.

• Evidence for plate tectonics: [Hint: You do not need to memorize the list below BUT could you describe how each of these lines of evidence support the theory of plate tectonics?] Also see pages 205-210
• Paleomagnetism  When iron rich minerals crystallize from a melt they will align in the direction of the Earth's magnetic field.  Some rocks contain minerals that do not line up or match the direction of this magnetic field.  This suggests that those rocks have been moved since they were formed - via plate tectonics.
  
• (Apparent) polar pandering Study of lava flows in North America and Europe showed that the iron rich minerals in these rocks were pointing towards two different north poles.  We know that there is only one magnetic north pole.  So this suggests that North America and Europe were once connected, and have since moved apart via plate tectonics.  
• Magnetic reversals and sea floor spreading Magnetic bands on the sea floor prove that the seafloor is indeed spreading at divergent boundaries.  
  
• Earthquake patterns The shallow, intermediate, deep focus earthquake pattern that is observed near ocean trenches supports the idea that an oceanic plate is descending into the mantle at these locations.  (Also see plate tectonics lab.)
  
• Ocean drilling Data on the age of sediments taken from the seafloor supports the idea that the seafloor is indeed spreading.
  
• Hot spots Chains of islands over hotspot, such as the Hawaiian Islands, is evidence that the plates are moving.  If the Pacific plate was not moving we would not have a chain of Hawaiin Islands,  but just one very large island.
• Why is the Earth's Geology Lucky?  See class notes and original article at: http://dsc.discovery.com/news/2008/01/11/plate-tectonics-earth.html

Earthquakes
Key Words: fault, earthquake, epicenter, focus, seismograph, P-waves, S-waves, surface waves (L-waves),
    intensity vs. magnitude (Mercalli scale vs. Richter scale), elastic rebound, fault creep, stick-slip, aftershocks,
    foreshocks, tsunami, liquefaction

Also refer to: Virtual Earthquake homework assignment, Mercalli Scale in-class assignment

• Which type of motion will likely cause a larger earthquake, stick-slip or fault creep?  Why? Stick-slip Why? Along a stick-slip fault, the segments of rock on either side of the fault remain locked for a period of time before they rupture.  This causes a build up of energy that is released during an earthquake.  A fault that experiences fault-creep motion is in continual, gradual movement.  This does not allow for a build up of a significant amount of energy.

• In addition to ground motion, what can cause damage during (or after) an earthquake?  List at least 4. tsunami, landslide, ground subsidence, fire

• Can earthquakes be predicted? ? No, not acurately.  Locations that have the greatest potential for earthquakes can be determined, but when a big quake will occur can not.

• Where do most earthquakes occur? On plate boundaries.

• Near subduction zones a distinct pattern of earthquakes has been observed.  Near trenches the quakes have a shallow focus, but the further away from the trench the deeper the focus of the quake.  Why?  (Also refer to earthquakes lab.)  The focus of an earthquake is where the earthquake originates.  The moving of the plate is causing the earthquake.  At a subduction zone, as the plate moves deeper and deeper into the Earth the focus becomes deeper and deeper.

• How many seismic stations are needed to determine the location of an earthquake epicenter? [Hint: How many did you use in the on-line homework assignment?] 3

• Be able to find the P-S arrivial time distance on a graph, measure the amplitude of the largest wave on a seismogram, and plot a Richter magnitude on a nomogram (all the things you did for your online homework assignment). The best way to study for this would be to go back and do the exercise again, and pay attention to what you are doing!

• What five characteristics define a mineral? naturally occurring, inorganic, solid, definite chemical structure, unique set of physical properties
• What type of atomic bonding produces the strongest bond? Covalent
• What are the two most common elements in the Earth's crust? Silcon and Oxygen
• What is a silicon-oxygen tetrahedron?   Could you identify a schematic sketch of one? See page 41.
  

• Bowen's reaction series predicts what minerals will first crystallize from a melt.
• What is the first mineral to crystallize?  olivine the last? quartz
  
• If a rock is heated what is the first mineral to melt?quartz the last? olivine
• Partial melting of a rock will produce a magma that is more felsic (higher in Si and O) than the original rock.  Why? When a rock melts the minerals that make up that rock start to melt in a specific order; the reverse of Bowen's reactions series.  Which means the most felsic minerals will melt first (quartz, then potassium feldspar, then muscovite mica).  If a rock is partially melted, meaning only part of it is melted not the whole thing.  The resulant melt is more felsic because the more mafic minerals that melt last did not get a chance to melt. 

• How does cooling rate affect the grain size of an igneous rock? the slower the cooling the larger (coarser) the grain size, the faster the cooling the smaller (finer) the grain size

• The nature of a volcanic eruption is influenced by the properties of the magma being erupted.  These include: composition, temperature, and the amount of dissolved gases.  Explain each of these three factors. (You may want to refer to Table 9.1 from your book.)The viscosity of a magma will play a key role in the nature of an eruption.  The more viscous the magma the more explosive the eruption, and vice versa.  Composition influences the viscosity of a magma, the higher the silica content the more viscous and thus the more explosive the magma is.  Thus a rhyolitic magma will likely erupt explosively while a basaltic lava will cause a relatively quiet eruption.  Temperature is also related to viscosity, the higher the temperature the lower the viscosity.  The more dissolved gasses the more explosive the eruption. In a viscous lava, the gasses are trapped, build up and then are released in a violent eruption.  In a low viscosity lava, the gasses escape more easily and thus there is no build up to cause a large, explosive eruption.

• What is viscosity?  A measure of a materials resistence to flow. Which will cause a more explosive eruption, a viscous magma or a non-viscous magma? viscous

• What is extruded from a volcano?
• Lava
• What is it? Molten rock that has reached the Earth's surface.
• Gasses
• What is the most common gas expelled by a volcanic eruption? Water and carbon dioxide.
• Why are they considered a source of air pollution?  Sulfur and nitrogen emitted from a volcano will combine with carbon dioxide in the atmosphere to form acid rain (sulfuric and nitic acids).
• Pyroclastics
• What are they? "fire fragments", volcanic particles ejected into the air
• Volcanoes
• What is a volcano?  A mountanous accumulation resulting from successive eruptions from one vent.
• Shield Volcanoes
• What type of lava is typically extruded by a shield volcano?  Basaltic. How does this influence the morphology (shape) of the volcano? This fluid lava results in a very broad, slightly domed feature.
• Cinder Cones
• What are they composed of? Pyroclastic material (cinders) from a low viscosity basaltic eruption.
  
• In a relative sense how large are they? Relatively small, and very steep sided.
  
• Why are they said to be parasitic? They often form on the flanks of other volcanoes.
• Composite Cones (Stratovolcanoes)
• What are they composed of? Alternating layers of lava flows and pyroclastic materials.
• Where on Earth are they common? At convergent oceanic-continental boundaries.(Hint: Think plate tectonics.)
• What type of lava is typically extruded? Andesitic (or technically rhyolitic, but since its so viscous its extremely rare to get this kind of lava flow.)
• What is a pyroclastic flow? hot, fast flow of gasses and ash
• What is a lahar?  Volcanic mudflow. What causes them to form? High amounts of rainfall at same time as eruption or the melting of snow and ice on top of a volcano as a result of an eruption.
• Intrusive Igneous Activity
• What is a pluton? An underground igneous rock body.
• How are they classified? By shape.
• What are the characteristics of a dike? a sill? a lacolith? a batholith? [Hint: Could you label these features on a figure?] See page 267 and Figure 9.25.
• Distribution of Igneous Activity
• Spreading Center Volcanism
• What happens during this type of volcanism? Two lithospheric plates spread apart, this decreases the pressure on the underlying mantle rocks (decompression melting), lowers their melting temperature, and causes partial melting.  This molten material then moves upwards and erupts at the surface.
• What type of magma is typically found here?  Basaltic. Why? The mantle is composed of ultramafic rocks, the partial melting of these rocks produces mafic lava (basalt).
• Subduction Zone Volcanism
• What happens during this type of volcanism? One lithospheric slab subducts beneath another, as it subducts it is heated and the volatiles are driven off.  This lowers the melting temperature of these rocks and causes melting.  This buoyant, molten material rises through the crust.  It may incorporate some of the crust as it moves through.
• What type of magma is typically found here?  Intermediate and maybe felsic Why? Partial meling and assimulation of the crust increases the silica content.
• Interplate Volcanism
• How does this originate? Hotspot, mantle plumes rise to the surface.
• Whay type of magma is typically found here?  Why? Hawaii (oceanic hotspot) is basaltic, because the mantle material is mixing with mafic rocks.  Yellowstone (continental hotspot) is rhyolitic and maybe andesitic because of partial melting of the crust.  Yellowstone has erupted basaltic lava in the past as well.  But because of it rhyolitic/andesitic components is considered to be one of the most explosive and dangerous types of volcanoes.