2. Explain the difference between relief and topography. 3. Define the four basi
ID: 118292 • Letter: 2
Question
2. Explain the difference between relief and topography.
3. Define the four basic types of faults. How are faults related to earthquakes and seismic activity?
4. How did the Basin and Range Province evolve in the western United States? What other examples exist of this type of landscape?
5. What is the relationship between an epicenter and the focus of an earthquake? Give an example from the Loma Prieta, California, earthquake.
6. Differentiate among the Mercalli, moment magnitude (M), and amplitude magnitude (Richter) scales. How are these used to describe an earthquake? Reference some recent quakes in your discussion.
7. What is a volcano? In general terms, describe some volcanic features.
8. Where do you expect to find volcanic activity in the world? Why?
9.What is the interplay between the resistance of rock structures and differential weathering?
10. Describe weathering processes operating on an open expanse of bedrock. How does regolith develop? How is sediment derived?
11. What role do joints play in the weathering process? Give an example from this chapter.
12. What is physical weathering? Give an example.
13. Why is freezing water such an effective physical weathering agent?
14. What is chemical weathering? Contrast this set of processes to physical weathering.
15. With what kind of minerals does carbonic acid react, and what circumstances bring this type of reaction about? What is this weathering process called?
16. What are the classes of mass movement? Describe each briefly and differentiate among these classes.
WORLD OCEAN FLOORExplanation / Answer
Answer – The map of the ocean floor shows tell-tale signs of plate movements. These movements are observed along the ocean bottom, especially along Mid-Ocean ridges and the trenches. For example, the Atlantic Mid-Ocean ridge and Challenger deep respectively. The wrinkles created by plate movements, as observed along the MOR are surficial manifestations of tectonics. Similarly, large number of transform faults along the MOR also point to this conclusion.
2. Explain the difference between relief and topography.
Answer – Relief stands for the quantitative difference of elevation between two reference points. Topography is the overall structural expression of the landscape that is perceived by an observer. For example the relief in the Appalachains mountain region is high and the topography is hilly.
3. Define the four basic types of faults. How are faults related to earthquakes and seismic activity?
Answer – Four basic types of faults – 1) Normal fault, 2) Reverse fault, 3) Slip faults (Stike-slip, Dextral/Sinistral Slip, 4) Thrust fault
The earth movements along a faulted terrain results in seismic activity and causes earthquakes. Slip faults in the San Andreas region of California generate seismicity and cause devastating earthquakes in the region.
4. How did the Basin and Range Province evolve in the western United States? What other examples exist of this type of landscape?
Answer – Basin and Range province evolved by the processes of extensive Faulting. This resulted into formation of Grabben and Horst structures that represent Basins and Ranges in the region respectively.
5. What is the relationship between an epicenter and the focus of an earthquake? Give an example from the Loma Prieta, California, earthquake.
Answer – A focus or hypocenter is the point of origin of the earthquake. It can be shallow (<10-20 km from surface) intermediate (~100 km) or deep (~300 km). The Epicenter on the other hand is the point on the Earth’s surface that is directly above the focus. For example, if the focus is 30 km deep in the California State and the first place in the state to receive Seismic waves is Loma Prieta in California then Loma Prieta is the Epicenter. Ofcourse it is not that easy to identify Epicentre. Triangulation method is used to ease the findings.
6. Differentiate among the Mercalli, moment magnitude (M), and amplitude magnitude (Richter) scales. How are these used to describe an earthquake? Reference some recent quakes in your discussion.
Answer – The Mercalli scale measures the intensity of the earthquake. It is set in the scale from I to XII. It is based on rather crude observations of people and damage assessed to an area post seismic event. The Richter scale measures the Magnitude of the earthquake. It measures the maximum amplitude of the seismic wave on a Wood-Anderson seismograph and calculates the Magnitude of the earthquake. But the magnitude is capped at 7.0. That means all larger earthquakes would always have a magnitude of 7.0 or less. To overcome this disadvantage, Moment magnitude (Mw) was introduced in 1979 by Hanks and Kanamori. Moment magnitude measures the magnitude of earthquake in terms of how much energy is released by the event.
7. What is a volcano? In general terms, describe some volcanic features.
Answer – A volcano is a vent in the earth’s crust through which magma, water and gases are released on the earth’s surface. Volcanic features – Volcanic cone, cinders, tephra, solfataras, pahoehoe (ropy lavas), aa (block lavas).
8. Where do you expect to find volcanic activity in the world? Why?
Answer – Volcanic activity is expected to be found around three regions viz, 1) Ring of fire, 2) Mid ocean ridges, 3) Hot spot regions. This is because these regions portray active plate tectonics. Tectonism generates enough magma to be manifested in the form of volcanoes on the surface.
9. What is the interplay between the resistance of rock structures and differential weathering?
Answer – Weathering of a rock depends not only on the physical and chemical agents but also on the rock composition. Some minerals weather early and easily than others. This is known as differential weathering. For example, Olivine weathers easily compared to quartz.
10. Describe weathering processes operating on an open expanse of bedrock. How does regolith develop? How is sediment derived?
Answer – On an open expanse of rock, depending on the geographical location, both physical and chemical weathering plays a role. Assuming a large sheet of granite is exposed in Kansas region. During summer it will largely face expansion and contraction due to temperature changes. This may result in an exfoliated rock. If the granite is well jointed, the water activity may cause formation of Tors and corestones, especially in winter. Regolith is a mass of unconsolidated material capping over a bedrock. Sediment is derived by continuous weathering and the consequent erosion of a rock.
11. What role do joints play in the weathering process? Give an example from this chapter.
Answer – Joints form as conduits for water to permeate or accumulate. The freeze and thaw action of water broadens the joint and results into subsequent weathering. Formation of Tors and Corestones is largely ascribed to Joint weathering
12. What is physical weathering? Give an example.
Answer – Involvement of physical or mechanical forces like wind, water, temperature, precipitation the the breakdown or weathering of a rock is known as physical weathering. An example – Exfoliation of rocks
13. Why is freezing water such an effective physical weathering agent?
Answer – Water expands when freezes. This increase in volume results in applying pressure on rocks. For example let’s assume water is lodged in the crevasses of a rock during daytime. At night time, if temperature drops sufficiently, the water freezes. Freezing causes expansion. But no space in the crevasse to expand. Hence cracks develop. Weathering proliferates.
14. What is chemical weathering? Contrast this set of processes to physical weathering.
Answer – Weathering caused due to chemical processes like oxidation, reduction, hydration, hydrolysis, carbonation etc is known as chemical weathering. While physical weathering directly breaks down the rock, chemical weathering alters the rock structure by changing its chemical composition. This changed composition is weak enough to get degraded by the agents of weathering like water and wind.
15. With what kind of minerals does carbonic acid react, and what circumstances bring this type of reaction about? What is this weathering process called?
Answer – Carbonic acid reacts mainly with limestones and other rocks having high organic content like mudstones. Presence of well jointed limestone topography, sufficient water in the form of precipitation are requisites for such reactions to take place. This type of weathering is known as carbonation and the geomorphological feature mainly formed here is that of a Karst topography (full of caves and sinkholes)
16. What are the classes of mass movement? Describe each briefly and differentiate among these classes.
Answer – Mass movements can be classified based on the movements and presence of water into flows, slides, slumps and falls (decreasing water content). A flow has maximum water concentration. It doesnot require steep slope like a fall to occur. A slide has less water than a flow but more than a fall. Slides and slumps mainly occur due to activation of a subsurface weakness in the form of a minor fault or weak-plane.
Related Questions
drjack9650@gmail.com
Navigate
Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.