OU LoginHere is a guide to help you focus on the important aspects of the course. Use this guide in conjunction with YOUR NOTES, the Quizzes and the tools within each chapter: the Focus on Learning questions at the beginning, the Chapter Review, Key Terms, Questions, etc. Study the figures (sometimes a picture is worth a thousand words, and is easier to remember). Don't save studying until the last minute!
You should know the properties (relative masses and charges) of the three subatomic particles that make up an atom, as well as where each part is found. What are the 8 elements that make up the crust of the Earth? Can you explain what makes an ionic bond? a covalent bond? Which type of bond is likely to link the Na to Cl in the salt structure? What type of bond forms between two oxygen atoms? What do the positions A, B, C, and D tell about element "X" in the following examples: AXB , CXD What is the importance of, for instance, "C" in the example?
What is the definition of a mineral (all 5 parts, as discussed in class)? Be able to list at least 5 physical properties of minerals - it might be good to know EXACTLY what they mean, too! Don't just give examples (metallic and pearly are examples of luster, but what IS luster?) We talked about components of minerals - why is FeO important? What is a silicon tetrahedron, and why is it important? What's the most common mineral type in the crust of the Earth? What are the four important variables that control whether a mineral will form?
What is the definition of a rock? What do we look for (hint: two categories) when we describe rocks? Why is each category important? Rocks are divided into three main groups: Igneous, Sedimentary and Metamorphic. Can you briefly but precisely describe how each forms?
Plate Tectonics
This paragraph may be short and sweet, but don't let that fool you! What four types of evidence that Alfred Wegener used to put together his Continental Drift Hypothesis (CDH)? What WAS his CDH? (include WHAT was supposed to exist before the significant change, WHEN did it exist, WHAT happened, WHEN did it happen, and WHY did it happen.) Why wasn't his idea accepted? What is the Sea Floor Spreading (SFS) hypothesis, and how did it come about? Add CDH + SFS and you get Plate Tectonic Theory (notice the change from Hypothesis to Theory ‑ why?). According to PTT, the lithosphere is broken into numerous plates that move around on the underlying, plasticly‑deforming asthenosphere. Describe the three types of plate boundaries ‑ what kind of motion, and what goes on ‑ and GIVE AN ACTUAL EXAMPLE OF EACH. What lines of evidence can be used to support Plate Tectonics? For example, how do earthquakes and volcanoes support the theory? How does Hawaii fit in? What drives plate motions?
The Ocean Floor
What proportion of the Earth's surface is covered by water? Which ocean is biggest? deepest? Be prepared to label the features of the ocean bottom ‑ identify a continental margin as active or passive, and label the shelf, slope, rise, trench, abyssal plain and mid‑ocean ridge. Be prepared to describe each of these briefly.
Smaller‑scale features include deep‑sea fan, seamount, and guyot. What are submarine canyons ‑ how are they maintained and how do they affect the availability of near‑shore sediment? What are turbidity currents, and what is their significance? List two examples of terrigenous, biogenous and hydrogenous sediiment. How is each formed? A fourth kind of sediment that is important is called "cosmogenous" sediment ‑ particles of dust and debris that enter the earth's atmosphere from space, most obvious during meteor showers.
Igneous Rocks
There are intrusive and extrusive igneous rocks - what's the difference? You can tell them apart by the textures that we studied: Phaneritic, Aphanitic, glassy, porphyritic, vesicular. If an extrusive rock is mafic in composition (Mg- And Fe-rICh), then it is called Basalt. If an intrusive rock is felsic then it is called a Granite. Compared to Basalt, Granite is less dense and has lighter-colored, larger mineral crystals in it. Also, be prepared to show that you know the different rock names and what they mean!
When we discussed igneous rocks, we first explored how magma is first generated (think: start with rock, end with magma). Explain why basaltic magma has a composition that is different from the mantle (peridotite) from which it is derived (another hint: think about partial melting). Igneous rocks form from crystallization during cooling of magma. Bowen's Reaction Series is important in the processes of igneous differentiation. Describe how granitic magma comes to be - how might it be related to basaltic magma (hint: think about crystal settling, also called fractional crystallization); what has to happen such that granite is eventually formed (as opposed to rhyolite - does magma cool slowly or quickly)? Here are some things to think about: as a basaltic magma (derived from partial melting of mantle peridotite) cools, Fe- and Mg-rich minerals (olivine, pyroxene) crystallize. Because they are more dense than the surrounding magma, they may sink to the bottom, depleting the Fe and Mg content in the remaining magma. This makes the remaining magma less dense, allowing it to rise further in the Earth's crust. At lower temperatures (higher in the crust), other minerals form, and at the lowest temperatures at which magma can exist, quartz forms.
Magma erupted at the surface of the earth is called lava. The viscosity of lava is related to its TEMPERATURE, SiO2 CONTENT, and GAS CONTENT. These factors control the type of eruption (quiet or violent) and the shape of the volcano that is created.
BASALT has high temp., low SiO2 and fairly high gas content, and therefore is generally a fluid lava (not viscous). Basaltic lava flows are typically thin, and they spread out over vast areas. After many flows, the resulting shape is that of a Shield. Hawaii is an example of a shield volcano; there are others. Variations can always occur: sometimes the lava retains its gases and so flows out in a fluid manner, with a ropy texture forming on its surface (pahoehoe). Other times the basalt loses much of its gas and becomes more viscous, oozing slowly out in a clinkery (rough, jagged) flow known as aa. Lavas with higher SiO2 contents are typically not as hot, and the silica may form complex molecules (polymers) in the magma, and so siliceous (felsic) lavas are more viscous (flow more slowly). These factors tend to override any effect that the addition of gas might have on making the magma less viscous. When lava does not flow easily enough to allow the gases to escape, violent explosions can occur. These explosions send material (pyroclastic material: ash and blobs of lava) into the air - and these pieces cool very quickly, and then land back on the earth. This spattering can result in the formation of a cinder cone. Cinder cones can be formed from any lava type, and are easily eroded because they consist of small, angular chunks of material that are not in equilibrium with surface conditions.
Many familiar volcanoes are composite cones (or stratovolcanoes). These form from alternating pyroclastic and fluid lava flows, and can build up into high peaks (Mt. St. Helens, Mt. Shasta, Mt. Rainier, most of the Andes, Mt. Fuji, Mt. Etna, etc.). These peaks may have craters associated with them, or they may have collapse structures known as calderas.
Draw a simple cross-section showing the difference in the slopes developed on shield vs. composite volcanoes . Why are the slopes different? What are some of the gases that are emitted from volcanoes? Which is most abundant? What kinds of volcanoes (and what compositions) tend to occur at different plate boundaries?What kinds of hazards are associated with volcanism?
Because volcanic material is not in equilibrium with surface conditions, weathering and erosion tend to reduce the loose pieces fairly rapidly. Some of the erosional remnants of volcanoes include pipes and necks; examples are Shiprock, NM and Devil's Tower, WY. INTRUSIVE bodies associated with igneous activity include dikes and sills, and the magma chamber beneath a volcano may solidify into a pluton; many plutons make a batholith.
Weathering is a process that forms materials that are in equilibrium with surface conditions. It can occur by both physical breakdown (mechanical weathering) and chemical alteration (chemical weathering). List four types of mechanical weathering. How does physical weathering alter the proportion of surface area to volume? What are three requirements that must be met in order for frost wedging to be effective? What are the products of weathering of each of the important minerals in Bowen's Reaction Series?
Soil is composed of 4 ingredients. What are they, and what are 5 factors that control the formation of soil?
Mass wasting is the downslope transport of material under the direct influence of gravity, with no transporting medium. What is the Angle of Repose, and what does it represent? (Hint: think about gravity and friction.) How does water affect slope stability? What are some other factors - both natural and human - that can trigger mass wasting? What steps can we take to reduce the probability of failure?
We classify mass wasting processes on the bases of type of material, style of motion, and speed of motion. Describe the important features of: rock fall; rock slide; slump; debris flow; lahar; earthflow; creep; solifluction. Which is fastest/slowest? Which causes the most damage overall? What is the evidence for creep, and how does it proceed?
Describe the two processes of lithification and their impact on the pore spaces between grains. What are three common "cements?" When we describe detrital sediments and sedimentary rocks, we find it useful to distinguish them on the basis of grain size. What are the four size ranges that we discussed in class? What is the rock name associated with each size fraction? Discuss the concepts of textural and chemical maturity and the processes of sorting and rounding, and what different degrees of each might tell about the sample. Discuss the features of the three sandstone varieties - quartz arenite, arkose, and graywacke - and at least one depositional environment in which you might expect to find them. Regarding some "typical" sedimentary features: distinguish between cross-bedding and graded bedding; describe ripple marks and mud cracks, and what they tell you about the environment in which they formed.
What is the primary basis for classifying chemical sedimentary rocks? How is the manner of their formation different from that of detrital sedimentary rocks? Limestone is the most abundant chemical sedimentary rock. Discuss the most common manner of formation, and list a few less common manners. Chert is another common rock that belongs in this category - what is it, and how does it form? What are a few rock names included in the Evaporites? Check out question #11 at the end of the chapter!
"Metamorphism takes place where preexisting rock is subjected to [conditions] that are significantly different from those in which it formed" (p. 164). What are the environmental variables that describe the conditions of equilibrium? What is Contact Metamorphism, and what is the texture that commonly results? Briefly describe the nature of a contact aureole.
Rocks subjected to Regional Metamorphism often develop foliation. What is this texture, and what two conditions must be met in order for it to be developed? List the four foliated rock names in order of increasing grain size. Can you describe the distinguishing features of each? Why is gneiss "banded" while the others are foliated - and how does this relate to an important change that occurs when schist becomes gneiss? Marble, Quartzite and Serpentinite are three metamorphic rocks that do not show foliation. Why is this? Where did they come from / what is the parent rock of each? How would you distinguish quartzite from marble? Check out question #5 at the end of the chapter.
Describe Earth's water budget - sometimes known as the Hydrologic Cycle. What are the five principle reservoirs? What are five means of transferring water from one to another? What is the source of energy that drives the system?
Running water has the greatest overall influence on the Earth's surface. It is responsible for shaping most features of the landscape in practically all environments. It creates floods and flood plains, can be used for travel, energy, and even irrigation. Some people even derive their drinking water from streams.
Streams do three important jobs that transform the landscape: erosion, transportation, and deposition. Which of these is performed by the stream in any one location is a matter of the energy of the stream and its environment. In the mountains, the stream's gradient is steep and so, therefore, is its velocity. The velocity controls the competence of the stream (its ability to carry larger particles). As the stream gets bigger, its discharge increases, as does its capacity (total amount of sediment carried) - what are some ways that we can measure discharge? Because of the high energy of the stream where the gradient is steep, the stream practices mostly erosion; gravel (or, after lithification, conglomerate) might be left behind. What are three forms of erosion that can be caused by streams? What is the base level of a stream? Once the particles have been picked up, they are transported as part of the dissolved, suspended, or bed load. How are they transported in each of these modes? Which carries the most material? What sedimentary size fractions characterize each? While they are transported, the grains become rounded. When the gradient becomes less steep, the velocity slows, resulting in a change in the competence, but not necessarily the capacity. This change in energy results in deposition, and the rate of change of energy can be determined by the degree of sorting. Deposition usually results in the laying down of a series of (nearly) horizontal layers, or beds, of alluvium. Can you explain how a delta forms and evolves? What is the role of distributaries in its formation?
In the mountains where the gradient is steep, river channels tend to erode into the rock to form narrow, v-shaped valleys. When the gradient becomes less steep, the stream tries to make a broader valley by lateral erosion as the stream meanders. During periods of high water, the stream may flood its banks, depositing mud in its flood plain. Describe the formation of a natural levee - what is it, what is its orientation relative to the stream, and why is it formed where it is? What are other natural features of meandering streams and flood plains? What can humans do to help control damage from flooding? Which option is the best? ;-)
Describe the four basic drainage pattern types and give examples of where you might expect to find each - what type of terrain, what kind of material on the surface.
Groundwater represents a significant resource to humans, and also helps shape certain parts of the world. Water enters the ground by infiltration, moving through the pore spaces of the material. If those pore spaces are not completely full of water, then the rest of the space contains air, and we call this section the zone of aeration. Eventually, the water makes it down to a place where the pores are completely filled with water - the zone of saturation. The boundary between these zones is the water table. Normally, groundwater tries to seek its own level, flowing very slowly around the grains of the material; the water table therefore often mimics the topography, although the water table tends to be more gentle . Some streams tend to lose water to the ground, and others gain water from the ground. Can you imagine the conditions necessary for these cases?
What is porosity? permeability? What kinds of materials make a good aquifers? aquitards/aquicludes? When we drill into an aquifer and start pumping out water, drawdown generates a cone of depression in the water table around the well. What is an artesian system, and what are three necessary conditions that must be fulfilled in order for one to exist? Give a real example (i.e., based on a real place where this happened) of the effects of groundwater mining.
Groundwater can dissolve certain components, the best example being the calcite in limestone. What are the stages of development of Karst Topography? How are stalactites and stalagmites formed?
How do we define a desert? Are deserts always hot, sandy, lifeless, and dry? HWhere do most of the "big" deserts of the world occur? Give some examples and tell what process is responsible for their positions at 15-30oN and S latitude. The Great Basin of Nevada represents a rainshadow desert - how does that form?
What is the most important type of weathering in deserts? This type of weathering generally results in "angular" landscapes - jagged mountains with little or no soil development sticking out of gentle plains. The principle agent shaping the landscape is still running water, which is so effective in part because of the lack of vegetation to slow it down, and also in part because when it rains, it pours - resulting in torrents of water. Some characteristic features related to water in deserts include arroyos, alluvial fans and bajadas, and playas. Other features include inselbergs - isolated mountain remnants with buried roots.
Although water is the predominant shaper of the landscape, wind also does some important work. How does the wind move sand in its bed load? What happens to the silt and clay? How does this affect the surface of the desert - how does deflation work, and what is the result? As sand is transported by saltation, it can be used by the wind to grind away at larger rocks, resulting in undercutting and some pretty wild carvings. It can also result in the formation of ventifacts. When sand is deposited, it might form dunes - can you explain why most dunes are asymmetrical? Which is the slip face - and why is it called that? It is interesting that the slip face tends to form an angle of repose of about 34o . What does each of the 5 dunes types that we talked about in class (Barchan, Longitudinal, Transverse, Parabolic, Star) tell you about the constancy of the wind direction and the supply of sediment? Can you tell them apart? What is loess, and why should we care?
Geologic Time
What is the doctrine of Uniformitarianism? What are the four principles of relative dating? There are two other principles: that of Original Horizontality and that of Lateral Continuity. How are they used? Can you distinguish the three kinds of unconformity ‑ angular unconformity, nonconformity, disconformity? Be able to label, in order, the various Eons and Eras of the Geologic Time Scale, and the ages that separate them. What is an isotope ‑ and what does the number 40 mean in 40K? Define the concept of half‑life. Are you prepared to calculate the absolute age of a mineral using the half‑life of an isotope? For example: Suppose there are 125 atoms of 40K and 875 atoms of 40Ar in a sample; given the half‑life of 40K = 1.3 billion years, how old is the sample?
Glaciers
What, specifically, is a glacier? Explain the glacial budget ‑ refer to the zone of accumulation and the zone of wastage/ablation. What constitutes a stationary glacier? What happens to make a glacier advance? recede? In each case, in which direction is the ice moving? What are two ways that glacial ice moves? There are three ways by which glaciers can erode the surface: plucking, abrasion and bulldozing. Can you describe how each works? Glacial striations, glacial polish, and rock flour can be produced by the combined actions of plucking followed by abrasion. Can you describe how a valley is transformed by glaciers from having a V‑shape to having a U‑shape?
Identify the following erosional landforms: arete, cirque, fiord, hanging valley, horn, pater noster lake, tarn, U‑shaped valley. Depositional features include till and stratified drift (how are these different?), lateral, medial and end (or terminal) moraines. How does a kettle form?
What do glaciers have to do with the greenhouse effect and/or global warming? What IS the greenhouse effect, anyway - how (IN DETAIL) does it work?
Shorelines
What three factors are involved in the formation of [wind-generated] ocean waves? Anatomy of a wave: crest, trough, wavelength, wave height, amplitude, wave base ‑ could you label these on a diagram? The presence of a wave indicates that energy is passing through the water, and the rate of passage is known as the period of the wave. What defines a deep‑water wave? In deep water, the motion of water particles is circular (these are oscillatory waves) as wave energy passes through, with circles getting smaller to a depth of 1/2 the wavelength. This depth is known as the wave base - add this sense of water motion to the diagram! Wave base may change with the seasons, and also during a very powerful storm or when sea level changes. When the column of circular motion comes in contact with the ground (or a rock, etc.), the bottom water begins losing energy to friction and to the sand grains. Eventually (when depth is about 1/20 wavelength), the base of the column can no longer support the overlying column, and collapse occurs ‑ the wave breaks. At this point the water carries the energy further by translation rather than by oscillation. Moving water is more capable of transporting sand particles, and so can induce erosion and abrasion.
Waves strike the beach obliquely, They are refracted near promontories (headlands), which results in a concentration of erosional forces. Bays are normally places of deposition (beaches ‑ note the grain size!) for sediment‑laden shorelines. If erosion occurs along a beach, perhaps due to removal of sediment, then that erosion causes formation of a corresponding wave‑cut cliff (sea cliff) and wave‑cut platform. Because rocks have different resistances to erosion, there may also be the formation of sea stacks and arches.
Rivers are the dominant suppliers of sediment to the CA coast. Sediment is then carried by longshore currents ‑ can you explain how this works? During the stormy winter months, sediment is pulled out away from the coast and drops out below wave base. It is then no longer available to beaches, and so it is out of the sediment budget of the coast. Deposition of sediment, in areas of low energy, forms spits; if a spit completely blocks the mouth of a river, we call it a bay‑mouth bar. Barrier islands can form where there is a large amount of sediment available. Describe what a tombolo is and why it forms where it does. Along coastlines that are operating "in the red," groins are often erected to "trap" sediment. What does the coastline look like shortly after groins are emplaced? What happens to the rate of erosion down‑"drift," where there are no groins? Other attempts to curb the enormous power of the oceans include jetties, breakwaters and sea walls. What are the differences among these ‑ what purpose is each designed for, and how does each work?
How are the coastlines affected by tectonic processes and climatic changes? What are emergent and submergent coastlines, and what features might we look for to identify them as such? What is an estuary, and what does it signify?
Draw a picture indicating, and explain the reasons for Spring and Neap tides.
Earthquakes and Earth's Interior
What is an earthquake? Describe the basic points of the Elastic Rebound Theory. Draw a simple diagram showing a cross‑section through the Earth's crust. On it label a fault and the focus and epicenter of an earthquake. Can you explain why the epicenter occurs where it does?
Seismic energy is released as Surface waves and as Body waves. For S‑ and P‑waves, describe how materials transmit each (what kind of motion), and what kinds of materials can and cannot transmit them. Of all the wave types, which is fastest? slowest? causes most damage overall? How do we use seismic waves to determine the location of the epicenter? How do we use them to determine the Richter Magnitude - what is the basis for this magnitude? What does an increase in magnitude mean, in terms of displacement and energy released? (Give an example.) Magnitude is a scientific measurement that may or may not be useful to most people. Many people would rather know the Modified Mercalli Intensity of an earthquake. What does this scale measure?
What 4 factors govern the damage that structures incur during earthquake shaking? (Hint: p. 330) What is a tsunami? Describe how a tsunami would appear in the open ocean, and what would happen once it arrived at a "harbor." What happens during liquefaction? Other destructive events related to earthquakes can be landslides, subsidence, fire, etc. With all this to fear, it would be "nice" if we could predict when the next Big One will strike. What information constitutes a useful prediction? Can we make predictions that are valuable? How do we go about making those predictions ‑ both short‑ and long‑range? What should we do to prepare for a big quake? When will it happen?
What do seismic waves tell us about the interior structure of the Earth? For example, what is the Moho, how do you pronounce its discoverer's name (ha ha), and what does it represent? The crust and uppermost mantle form a layer called the Lithosphere, which behaves differently (explain) from the underlying Asthenosphere. What is the nature of the inner and outer core of the Earth, and how do we know?
Folds and Faults
Draw a cross‑section of an anticline and of a syncline. Where are the oldest beds relative to the youngest? Could you tell a dome from a basin by looking at the trend in age of the layers exposed at the surface?
Draw block diagrams showing the movements (arrows included) associated with the four kinds of faults (normal, reverse, thrust, strike‑slip) and label the hanging wall and footwall blocks, where appropriate. What kinds of faults would you expect in a compressional (convergent margin) environment? a tensional (divergent margin) environment? a shearing (transform margin) environment? What are Accreted Terranes, and what do they have to do with the growth of the N. American continent? (see fig. 17.17)
This page was originally posted on the new server on 11 March 2012 by Mark Boryta