Discussion
1. Before you answer the questions in this Discussion Forum, read the publication “This Dynamic Earth”.

2.  Choose any 3 of the 8 topics/questions below and answer the related questions in the appropriate thread of this Discussion. Each well-thought relevant answer to the question, consisting of a substantive paragraph is worth up to 5 points for a total of 15 points for this assignment. The late policy is 10 % per calendar day. The due date is in the calendar in the global navigation bar.

Q.1  Distribution of Volcanoes: Why most volcanoes in the world (95%) are located along mid-oceanic ridges or found in chains parallel to trenches?

Q.2: Sea-floor topography: Why are trenches bordering chains of volcanoes and island arcs? What happens at trenches? How do oceanic ridges form?

Q. 3 Ocean floor age: Why the ocean floor is progressively older as you move away from the oceanic ridge? Why there is no ocean floor on Earth older than ~ 200 million years?

Q. 4: Ocean floor magnetization: Explain the origin of the magnetization pattern of the ocean floor.

Q. 5: Distribution of earthquakes: Why earthquakes occur only in narrow zones of the Earth (i.e. mid-oceanic ridges and trenches)?

Q. 6: Distribution of Mountain Ranges: Why large mountain ranges are also located in such zones? What caused these mountains to form?

Q. 7 Wegener’s arguments: How does plate tectonics confirm the evidence and theory of continental drift that Alfred Wegener proposed? Why the continents seem to match up like in a puzzle? Why are fossils of long-extinct animals found on different continents? Why rocks bordering the continents around the Atlantic Ocean have the same age, composition, and geologic structures? How can the puzzling pattern of glacial striations on different continents in the southern hemisphere be explained? How can we explain the occurrence of Paleozoic glacial deposits near the equator only on some continents?

Q. 8: Hot spots: What is the origin of chains of seamounts and volcanic islands that display a straight alignment and a regular age progression from older to younger?

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