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1. Describe the evidence Wegner used to support continental drift

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Continents seem to fit together South America and West Africa Rock bodies are continuous across continents Fossil ranges cross continents in odd ways Continents show evidence of VERY different climate in their past.

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2. What were some or the problems with continental drift

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Wegner had no idea how the continents were being moved. Wegner thought the continents were moving through the solid rock of the ocean floor. There were other explanations for the rock and fossil distributions that at the time made more sense.

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3. What role did sea floor spreading have in the development of plate tectonic theory a. How did it help overcome the shortcomings of continental drift.

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Gives us an idea about how the continents are being moved. • Does away with the problem of moving the continents through the ocean floor because the ocean floor is moving too. A

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4. Explain how magnetic polarity reversals are used to support the theory of plate tectonics.

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Vine and Matthews • Found that the magnetic polarity that they observed at the Mid Atlantic Ridge in Iceland: • Matched the record that we see on land. • Was a mirror image on either side of the ridge

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Convective pushing

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• occurs at the mid ocean ridge as new material is brought to the surface

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Basal drag

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Occurs in the middle of the plate as the convection cell moves material (this is probably the most important)

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• Slab pull:

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occurs at trenches as material is sucked down.

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Ridge slide:

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the plate is moving "down slope" driven by gravity.

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6. Describe the features and processes associated with divergent plate boundaries including triple junctions, and mid ocean ridges, give examples of each.

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• Divergent: areas where plates are moving away from each other. Ice land ? Mid-ocean ridges are divergent boundaries -Atlantic Mid-Ocean ridge ? Triple junction: things tend to split apart in threes

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• Divergent:

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Divergent (Constructive) Margin A plate margin where two oceanic plates are moving away from each other. Divergent margins are responsible for the formation of ocean basins, which start out as rift valleys e.g. the African Rift. As the plates move apart, pressure on the underlying mantle is reduced and it partially melts to form basalt magma. New oceanic crust is formed at the ridge then moves away in both directions, cools and subsides. These margins are characterised by shallow focus earthquakes and basaltic volcanism. An example is the Mid Atlantic Ridge.

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? Mid-ocean ridges

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Mid Ocean Ridge The junction between two oceanic plates along a divergent (constructive) plate margin. The ridge comprises a submarine mountain chain of basaltic volcanoes and is up to 1.5 km higher than the adjacent abyssal plain. The central part of the ridge has a rift valley running through it and the ridge is offset sideways by transform faults eg the Mid Atlantic Ridge.

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? Triple junction:

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Triple Junction The point where three lithospheric plates meet. It has been suggested that mantle plumes are responsible for the upward doming of the crust at these locations, producing a three-way radial fracture. An example is the Red Sea, Gulf Aden and East African Rift Valley.

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7. Describe the processes occurring at transform plate boundaries.

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areas where one plate is sliding past another ? Lots of small shallow focus earthquakes ? Example: San Andreas Fault Ca ? No Volcanoes Usually shallow, small earthquakes usually only 1 to 3. Pacific tectonic plate next to North American plate

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• Convergent:

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areas where plates are coming together.

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8. Describe the processes that are operating at each of the three types of convergent plate boundaries and give examples of each.

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Convergent: areas where plates are coming together

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Continent-Ocean

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Oceanic crust meets continental crust and is subducted beneath it producing volcanoes and shallow to deep earthquakes Andes Moutain, Cascade Moutains.

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? Continent-Continent:

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Two continental plates collide producing large mountain ranges. No volcanoes but lots of earthquakes.Himalaya Mountains

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? Ocean-Ocean:

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Two oceanic plates come together forming a trench with volcanoes behind it and shallow to medium focus earthquakes. Virgin Islands

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9. What is the definition of a mineral?

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• Naturally occurring • Inorganic (not alive) • Solid • Definite chemical composition • Crystal form

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10. Define: Igneous, sedimentary, metamorphic, mafic, intermediate, felsic.

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Mafic: low amounts of silica e.g. Basalt Intermediate: Medium amounts of silica e.g.Andesite Felsic: high amounts of silica e.g. Granite

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Metamorphic rocks

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form by applying heat and pressure to preexisting rock.

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Sedimentary Rocks

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Form from sediments or from chemical precipitation. e.g. limestone.

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Igneous -

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form from molten rock

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11. Define the following igneous textures and relate them to the cooling speed of the magma or lava: Coarse grained, Fine Grained

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Texture- how big the mineral grains are and is related to cooling speed

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• Coarse grained-

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cool slowly below ground e.g. Granite

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• Fine Grained-

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cool quickly above ground e.g. Rhyolite

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12. What is the difference between clastic and chemical sedimentary rocks. Give an example of each.

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Sedimentary rocks tel you the environment of deposition different environments produce different rocks. Being able to tell the environment from the rock is valuable tool in the study of the history of the Earth.

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• Clastic- Sedimentary Rocks

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form from Sediment being cemented together to make a rock.

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• Chemical-

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form from chemical precipitation. e.g. Limestone

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13. In general, how are clastic sedimentary rocks classified?

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Classified by the size of the sediment ? These are named based on the size of the sediment.

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14. Name the rock for each grain size (pebble, sand, silt. clay)

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? Pebble- conglomerate ? Sand- Sandstone ? Silt- Siltstone ? Clay- shale.

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? Pebble-Sedimentary rock

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conglomerate

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? Sand-Sedimentary rock

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Sandstone

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? Silt- Sedimentary rock

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Siltstone

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? Clay- Sedimentary rock

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shale.

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15. What is the difference between foliated and non foliated Metamorphic rocks.

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Metamorphic rocks- form by applying heat and pressure to preexisting rock. • Foliated- have a layered 'texture' from mineral grains being forced into alignment during metamorphosis e.g. Geniss Non foliated- no alignment of mineral grains e.g. Marble

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Metamorphic rocks-

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form by applying heat and pressure to preexisting rock.

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• Foliated-

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have a layered 'texture' from mineral grains being forced into alignment during metamorphosis e.g. Geniss

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Non foliated-

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no alignment of mineral grains e.g. Marble

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16. What is the relationship between foliation and metamorphic grade? (better foliation ie. Gneiss means higher grade)

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Higher metamorphic grade means more heat and pressure With foliated rocks one can infer the degree of metamorphism from the degree of foliation ? Low grade- slate Low heat and pressure ? Intermediate grade- schist ? High Grade- gneiss Hight heat and pressure

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17. Given appropriate drawings label Right lateral, left lateral, normal and reverse faults. What is the general tectonic setting for each of these

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Strike slip faults: The portions of the crust are moving "by" each other. - Sliding past each other. Transformation boundary Right lateral. The block opposite the one you're standing on is moving to the right. Left Lateral. The block opposite the one you're standing on is moving to the left. Happen at transformation boundaries. San Andres fault Normal faults: The hanging wall is moving down relative to the foot wall.- Divergent- pull- "normal"- down Dip slip faults: The portions of the crust are moving "over" each other. Reverse faults The hanging wall is moving up relative to the foot wall.- convergent-push- "reverse"- up: There are four types of fault in two catagories

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Reverse faults

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The hanging wall is moving up relative to the foot wall.- convergent-push- "reverse"- up

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Normal faults

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The hanging wall is moving down relative to the foot wall.- Divergent- pull- "normal"- down

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Dip slip faults

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The portions of the crust are moving "over" each other.

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Strike slip faults

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The portions of the crust are moving "by" each other. - Sliding past each other. Transformation boundary

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Right lateral faults

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The block opposite the one you're standing on is moving to the right.

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Left Lateral faults

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The block opposite the one you're standing on is moving to the left. Happen at transformation boundaries. San Andres fault

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18. Define Focus, Epicenter

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Focus: the area along the fault where the slippage occurs Epicenter: the point on the ground surface above the focus^ There are two words that describe where a earthquake can happen

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19. What is the difference between surface and body waves?

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• Surface waves: Waves that travel along the surface of the earth, similar to waves in water. • Body waves: waves that travel within the earth. - Through the Earth.

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20. What is the difference between p waves and s waves? Which travels faster? Which can travel through liquid?

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• P waves: waves that travel by compressing material • Travel relatively fast , almost twice as fast • Can travel through solid and liquid • S waves: waves that travel by displacing material at right angles to the direction they're traveling in • Travel relatively slow • Can't travel through liquid

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21. In general how can you use p and s waves to locate the epicenter of an earthquake

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We can use the difference in the speed between P waves and S waves to determine how far away the earthquake epicenter is by triangulating from three different seismic stations. The intersection of the 3 circles is the epicenter

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22. If p waves and s waves arrive at about the same time are you far away or close to the epicenter?

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Really close to the epicenter and really close to the earthquake.

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23. What is the difference between the Mercalli scale and the Richter scale?

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The Mercalli scale is qualitative and is based on the damage done by the earthquake and how it was perceived by people. Changes as you get closer to the Epicenter. The Richter scale is quantitative. It's calculated by a formula taking into account the size of the largest S wave and the distance from the Eipcenter. Each whole number increment on the Richter scale represents 30 times more energy released

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24. How do Tsunami's form?

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• Tectonic forces • Earthquakes • Volcanoes • Above and below water landslides • Meteor impact 90 % of Tsunamis happen in the Pacific Ocean • On order for a Tsunami to be generated the headwall must rebound upward during the earthquake Rock has to go up into the water

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25. Explain the role that viscosity plays in determining the nature of a volcanic eruption

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Viscosity is defined as Resistance to flowing. Highly viscous things resist flowing Honey Low viscosity liquids flow easily Water Highly viscous volcanoes erupt violently Less viscous volcanoes do not erupt violently

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26. Explain the role that silica plays in determining viscosity

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IIn Lavas and magmas viscosity is controlled by the amounts of silica. Lots of silica makes a more viscous magma or lava because silica tends to make chains and other structures that make it harder for the molten rock to flow.

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27. How does a magma's composition relate to its viscosity?

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Mafic magmas have very little silica and are not very viscous. These magmas produce volcanoes that aren't very explosive (Hawaii) Felsic magmas have more silica and are very viscous. These magmas usually cool underground and don't produce volcanoes. (Stone Mountain) Intermediate magmas have little enough silica to make it to the surface but enough to be very explosive. (Mt. Saint Helens) Magmas that have to travel through the earth's crust become more felsic and thus more explosive.

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28. Name and briefly describe the three types of volcano

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Shield volcano Very large in size Not very violent Most of the material extruded is lava Cinder cones Relatively small Often associated with other volcanoes Extrude mostly pyroclastic material (ash and rock) Most numerous volcanoes on the planet Composite cone Combination of lava and pyroclastic material Very explosive Most are located around the Pacific Medium size Hotspot volcanism Hotspots are isolated areas where magma is coming to the surface. This type of volcanism produces strings of volcanoes as the plate moves over the hotspot

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29. Name and briefly describe the hazards associated with volcanoes (six ways to die on a volcano)

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1-Gasses Volcanoes send all sorts of toxic gasses into the air 2-Lavaflows Lava can be up to 2,000 F at that temperature what it doesn't melt it will set on fire. Relatively few people die from lava flows because they generally don't move that fast. Most people who die from lava flows are messing around with it. 3-Tephra: anything solid ejected from a volcano. It ranges in size from ash to house sized blocks of rock Ash can fall hundreds of miles from the volcano. Its weight can cause structures to collapse, it can clog machinery and lungs, make roads slippery and bury buildings. 4-Lahar: a very fast moving mud flow down the flanks of a volcano (mudslides) 5-Pyroclastic flow: high-density mixtures of hot, dry rock fragments and hot gases that move away from the vent that erupted them at high speeds. (All the ash coming back down after it goes up) 6-Landslide: large masses of rock and soil that fall, slide, or flow very rapidly under the force of gravity. Lightning

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30. What is the difference between relative and absolute dating?

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Relative time: which rocks are older and which rocks are younger? Absolute time: How old are the rocks? Actual date. Absolute dating Atoms are made up of three components Protons: determine what element it is. Atomic number Electrons: determine what the charge is Neutrons: Determine what isotope it is. Proton plus an electron Protons + Neutrons= Atomic weight

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31. How do the law of superposition, principle of original horizontality and principle of cross cutting relationships work?

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Relative dating • The law of superposition: the older rocks are on the bottom the younger rocks are on the top • Principle of original horizontality: Rock layers are generally deposited horizontally • Principle of cross cutting relationships: when faults or igneous intrusions cut through a rock they are younger than the rock they cut.

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32. Define and inclusion and tell how it relates to relative dating

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• Inclusions: Pieces of one rock contained within another. The inclusion is older than the rock that contains it

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• Principle of cross cutting relationships:

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when faults or igneous intrusions cut through a rock they are younger than the rock they cut.

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• Principle of original horizontality:

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Rock layers are generally deposited horizontally

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• The law of superposition:

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the older rocks are on the bottom the younger rocks are on the top

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33. What is an uncomformity?

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Unconformities An unconformity is a gap in the rock record.

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34. Define isotope

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Atoms are made up of 3 components. protons: determine what element it is. Atomic Number Electrons determine what the charge is Neutrons: Determine what isotope it is.Proton +an electron Proton + Neutrons= Atomic Weight

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35. Define half lifeelectron

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A half life is the amount of time it takes for half a element to decay.

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36. How do you determine the age of a rock using radioactive isotopes?

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So to figure out how old a rock is.: • Measure the amount of parent and daughter isotope you have. • Determine how many half lives have past • Multiply the number of half lives by the length of a half life to determine the age of the rock

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