Questions and Answers of Geology

Name two main characteristic minerals of each of the three main metamorphic facies of Fig. 6.5.
What is burial metamorphism?
At what temperature does melting of preexisting rocks occur? (See Fig. 6.5.)
Metamorphism occurs at depth. Since geologists cannot see this going on, can they apply the axiom of “the present is the key to the past”?
During metamorphism, most chemical reactions are isochemical. Explain.
When the chemistry does change, what two ingredients are most commonly involved?
What happens to a conglomerate during metamorphism under directional pressures?
A special type of a metamorphic rock is a cataclastic rock. How is it formed?
Figure 6.4 shows metamorphic zones
Name and define the three major classes of mineral resources
Why are coal, oil, and natural gas called “fossil fuels”?
Why don’t coal, oil, and natural gas fit the accepted definition of a mineral? (See Problem 2.21)
What are peat, lignite, and coal?
How was coal formed?
Is coal in short supply?
What are the four basic requirements for an oil or natural gas field?
Name the five types of oil and gas traps shown in Fig. 7.3
Why do oil and natural gas accumulate in the traps shown in Fig. 7.3? (See Fig. 7.7.)
What is the likely source rock of petroleum and natural gas?
Where in North America are petroleum and natural gas found (Fig. 7.4)?
What thickness of cover rock is generally thought necessary to generate petroleum and natural gas from organic material?
What are the geologic ages of the petroleum and natural gas deposits in the United States?
In which rock types are oil and gas found?
What is oil shale?
Where are the big reserves of oil shale in the United States? (See Fig. 7.5.)
What are tar sands, and where are the earth’s largest known deposits? (See Fig. 7.6.)
Which processes—igneous, metamorphic, or sedimentary—form valuable mineral resources?
What is an ore?
Give an example of a mineral formed by primary igneous processes.
Is iron ore a resource that is in short supply?
Where are iron deposits found?
What is the main ore mineral of iron, and does it have an igneous, sedimentary, or metamorphic origin?
What is the main ore mineral of aluminum, and what is its origin?
Name a main ore mineral of copper, and is it igneous, sedimentary, or metamorphic?
Name the main ore mineral of zinc and give its origin.
Name the main ore mineral of lead and give its origin
Where are the rare earth elements such as zirconium, lithium, beryllium, and columbian‘tantalum found?
Why do quartz and calcite veins sometimes contain ore minerals such as native gold?
How are placer gold deposits formed?
Why can’t common rock be mined for elements such as copper? That is, why must high-grade deposits be found?
Metals such as manganese, nickel, cobalt, tungsten, and vanadium are also necessary in our modern civilization. What is their main use?
What is the nuclear fuel of the nuclear industry?
Where does most silver come from?
What is gypsum, how does it form, and what is its main use?
Why are phosphates an important nonmetallic mineral resource?
What minerals, other than native gold, are found as placer deposits?
How do diamonds form?
What is a possible future source of manganese?
What is the origin of the large iron ore deposits of the world? (See Fig. 7.8.)
How many times richer is copper ore of (a) 5 percent copper, compared to the average crustal abundance of 0.0058 percent and of (b) 0.25 percent copper, the lowest grade mined?
What are the three main metals that are mined in large quantities?
What is a porphyry copper deposit?
What are probably the two most important mineral resources which must be conserved because of their necessity to life?
Describe supergene enrichment (secondary enrichment) of a pyrite- and chalcopyrite-bearing rock by weathering processes (Fig. 7.9).
Calculate the amount of iron (weight percent) to the nearest whole percent in each of the following iron minerals: Magnetite (Fe3O4), hematite (Fe2O3), goethite [FeO(OH)], and siderite (FeCO3).
Where are the biggest gold deposits in the world, and what type of deposits are they?
What is the role of an economic geologist?
Why is it more difficult to find mineral resources today than it was in the first half of the twentieth century?
How is geophysics used in the search for petroleum?
How is geophysics used in the search for mineral deposits?
How is geochemistry used in mineral prospecting?
What is the chemical composition of petroleum?
What are the differences in the combustible properties of lignite, bituminous coal, and anthracite coal?
Where is most of the world’s petroleum located?
What country produces most of the world’s diamonds?
What country produces most of the world’s other gemstones (ruby, sapphire, and others)?
What countries produce most of the world’s bauxite?
What countries produce most of the world’s copper?
Which type of petroleum trap was most easily discovered in the early days of petroleum exploration? (See Fig. 7.3.)
What is the hydrologic cycle, and how can it be expressed in words?
What is transpiration?
What is the difference between weathering and erosion?
What are the agents of erosion?
What is the most important agent of erosion?
When and where do the agents of erosion deposit their loads?
What is a regolith (Fig. 8.2)?
Beneath a 500-million-year-old lava flow is a 3-m-thick regolith of decayed rock fragments, red iron oxides, and cation-deficient clay minerals. Why is the geology student who discovered this excited
What is base level?
How do talus piles (talus cones) form? (See Fig. 4.4)
What are the two classes of mass (gravity) movements?
What is a rock glacier, and why does it move?
Why do mudflows move?
What is the angle of repose (the steepest angle at which a pile of sand will stand) of loose dry sand?
What is solifluction?
Does soil creep operate in warmer climates as well?
What generally displaces the blocks on a cliff, forming talus piles?
What is colluvium?
Are avalanches (snow slides) mass movements?
What are landslides?
Briefly describe the Gros Ventre landslide that occurred in 1925 near Jackson Hole, Wyoming.
Flow does freeze-thaw action aid downslope movement of material?
What causes material that was previously stable to move downslope under the influence of gravity, either slowly or rapidly?
Whereas oversteepening makes slopes unstable, what actually triggers rapid mass movements?
How fast can rapid mass movements move?
How can one distinguish mass movement deposits from water-moved material?
In Fig. 8.5, the highway department is clearing a mudflow off a highway. What will probably happen next?
What kind of mass movements might be expected in areas underlain by limestone or dolomite, as in Florida?
See Fig. 8.6. Your good friend has the opportunity to buy this riverside land in a beautiful canyon at good price. She wants to build a log cabin on the site. Knowing some geology, what should you
Many massive debris flows are related to volcanism, as in 1985 when a volcanic eruption in Columbia caused debris flows that buried a village and about 20,000 people. Why are volcanoes often the
Can mass movements be predicted?

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