Plate Tectonics – Practice Questions 1. Please fill in the ✓ Solved
1. How many large plates form the outer shell of the earth?
2. What lies directly beneath the crust?
3. The upper mantle and crust make up what major tectonic feature of our planet?
4. What lies directly beneath the lithosphere and is around 200 km thick?
5. Continental crust is _________ than oceanic crust.
6. Oceanic crust is on average how thick?
7. A common rock type found within continental crust is called __________.
8. A common rock type found within oceanic crust is called __________.
9. According to plate-tectonic theory where is new oceanic crust being formed?
10. Where are melts most likely to be produced by the adiabatic rise of mantle?
11. The San Andreas fault is a classical ___________ boundary.
12. The East Pacific Rise and the Mid-Atlantic Ridge represent ____________ boundaries.
13. What is subduction?
14. What is the likely cause of melting of mantle material along convergent margins?
15. The inner core is composed of _______ and ________.
16. What state is the inner core likely in?
17. The outer core is ____ dense than the mantle.
18. Most of the volume of our planet is composed of __________.
19. The Mohorovicic discontinuity separates the __________ from the __________.
20. What produces the Earth’s magnetic field?
21. The asthenosphere is composed of __________ _________ mantle.
22. New lithosphere is produced at ___________________ ________.
23. Lithosphere is destroyed at _____________________ ________.
24. The mesosphere underlies the ____________________.
25. Please list the seven major lithospheric plates of our planet.
26. The trailing edge of the South American plate lies where?
27. Silicate liquids that exist beneath the surface of the Earth are called ________.
28. Silicate liquids that have flowed out onto the Earth's surface or seabed are called ________.
29. Strato or composite volcanoes are typical of _________________ _______.
30. Mt Shasta and Lassen formed in what kind of tectonic setting?
31. Beneath arcs at what depth does melting likely occur as a result of dehydration reactions?
32. What are the four driving forces behind plate motion?
33. Forearc basins occur between ___________________ __________ and _______________ _____.
34. What kinds of plate boundaries are found in California?
35. Which of the seven major lithospheric plates consists mostly of oceanic lithosphere?
36. The San Andreas fault separates the ____________ plate from the ________ _________________ plate.
37. Where is the Juan de Fuca plate?
38. Where is the Pacific plate?
39. On the following map please identify the 7 major lithospheric plates pointed to by the labels A, B, C, D, E, F, and G.
40. On the following illustration please identify the major components of a convergent margin pointed to by the labels A, B, C, D, E, F, and G.
41. On the following illustration please identify the major tectonic components of the western North American margin labeled (A), (B), (C), and (D).
42. On the following illustration please identify the features pointed to by labels A and B.
43. On the following illustration please identify the feature labeled A.
44. Which of the following, A or B, is representative of a fast-spreading center?
45. As plates move around on the globe they often times collide with each other. Examples include arc-arc and arc-continent collisions.
46. At least twice in the distant past, all of the continents on planet Earth assembled into a supercontinent. The earliest supercontinent formed about 1.1 b.y. to 750 m.y. ago, and the latest formed about 248 m.y. ago. What were the names of the former and latter supercontinents?
47. Please identify the features pointed to by the labels A, B, C, and D. What continent lies in the middle of the image? What oceans lie to the west and east of this continent?
48. The expanding Earth hypothesis was first formulated in the 1950s by S. Warren Carey, an Australian geologist. Though Professor Carey recognized sea floor spreading and the idea that the continents had once been assembled into the supercontinent of Pangaea, he did not recognize an important element of the modern-day plate tectonic paradigm. What was that element and how does it weaken the expanding Earth hypothesis?
Paper For Above Instructions
Plate tectonics is a fundamental theory in earth science that describes the dynamic processes of the Earth's lithosphere, which is divided into several large plates. These tectonic plates float on the semi-fluid asthenosphere beneath them. Understanding plate tectonics is crucial to explaining various geological phenomena, including earthquakes, volcanic activity, and the formation of mountain ranges.
1. Large Plates of the Earth
There are seven major tectonic plates that form the outer shell of the Earth: the Pacific Plate, North American Plate, Eurasian Plate, African Plate, South American Plate, Antarctic Plate, and the Indo-Australian Plate. These plates interact at their boundaries, leading to a variety of geological activities.
2. Structure Beneath the Crust
Directly beneath the Earth's crust lies the upper mantle, which is rigid and extends down to about 700 km. The lithosphere, composed of the crust and upper mantle, is supported by the underlying asthenosphere, which is about 200 km thick and softens as a result of increased temperature and pressure.
3. Tectonic Features: Crust and Mantle
The upper mantle and crust together form the lithosphere, which is a critical tectonic feature influencing the movement of tectonic plates.
4. Lithosphere and Asthenosphere
Beneath the lithosphere lies the asthenosphere. The asthenosphere is a plastic layer of the upper mantle, which allows for the movement of tectonic plates above it.
5. Comparison of Continental and Oceanic Crust
Continental crust is generally thicker and less dense than oceanic crust. Oceanic crust averages about 5-10 kilometers in thickness, while continental crust can be up to 70 kilometers thick.
6. Common Rock Types
A common rock type found within continental crust is granite, while basalt is typically found in oceanic crust. These differences in rock types contribute to the varying density and thickness of the crust.
7. Formation of New Oceanic Crust
According to plate-tectonic theory, new oceanic crust is formed at mid-ocean ridges. This process occurs through volcanic activity where magma rises from the mantle and solidifies at the ocean floor.
8. Melting of the Mantle
Melts are most likely produced by the adiabatic rise of mantle material at divergent boundaries where tectonic plates move apart.
9. Types of Plate Boundaries
The San Andreas Fault represents a transform boundary, while divergent boundaries, such as the East Pacific Rise and Mid-Atlantic Ridge, are where plates pull apart.
10. Subduction and Melting Processes
Subduction occurs when one tectonic plate moves under another and sinks into the mantle. This process is driven by gravitational forces and, along convergent margins, it creates conditions for melting due to the release of water from descending plates.
11. Composition of Earth's Inner Core
The inner core of the Earth is composed mainly of iron and nickel, and it is thought to exist in a solid state due to immense pressures despite high temperatures.
12. Earth's Magnetic Field
The Earth's magnetic field is produced by the movement of molten iron and nickel in the outer core, contributing to the geodynamo effect.
13. Major Driving Forces of Plate Motion
The four primary driving forces behind plate motion are mantle convection, slab pull, ridge push, and gravitational forces. These forces interact to influence the movement and behavior of tectonic plates.
14. Features of Forearc Basins
Forearc basins occur between convergent oceanic-continental margins and volcanic arcs, and they are often subjected to sedimentation and tectonic activity.
15. Geological Phenomena in California
California features transform boundaries, specifically the significant San Andreas Fault, which separates the Pacific Plate from the North American Plate.
16. Expanding Earth Hypothesis
The expanding Earth hypothesis proposed by S. Warren Carey suggested that the Earth’s volume has increased over geological time, but it does not encompass the concept of plate tectonics. The recognition of tectonic plate dynamics weakens this hypothesis as it explains the rearrangement of continental landmasses without necessitating the increase in Earth’s size.
Conclusion
Plate tectonics is essential for understanding the Earth’s geological processes. The interactions between different tectonic plates shape our planet's surface and influence various natural phenomena. A thorough comprehension of questions surrounding plate tectonics provides insight into the past, present, and future of our planet.