InClass_Activity

Physical Geology Chapters 10 and 11: Seafloor, Mountains and Topography Part 1 : Divergent Boundary A divergent boundary in the center of an ocean is shown below with arrows showing the direction the crust is moving. 1) Where is the oldest crust found? A B C 2) If each plate is moving at a rate of 2 cm per year, roughly how long did it take for Rock C to reach its current location? 0 years 2 years 4 years 8 years 3) What is the age of the rocks at location B? 0 years old 2 years old 4 years old 8 years old 4) What is the age of the rocks at location C? 0 years old 2 years old 4 years old 8 years old 5) Why should your answers to Questions #2 and #4 match? Revise your answers if necessary. Reason being, it took 2 years to get where it is now assuming ‘B’ is the 0 year mark. 6) A map of the Atlantic Ocean is shown to the right. Where are the oldest rocks in the Atlantic found? D E F Briefly explain your answer. E Is the divergent boundary 7) Two students are debating about the relative ages of the rocks in the Atlantic Ocean. Student 1: The oldest rocks are located at E because it is the farthest from a continent. The rocks would take a really long time to get to the middle of the ocean. Student 2: But divergent boundaries are found in the centers of oceans. This means that rocks at E are really young. D is farthest from the divergent boundary, so that’s where the oldest rocks are. With which student do you agree? Why? D E F ABC (The box is 10 cm wide)

I agree with student 2 because as I stated in question 6, E is the divergent boundary so D is in fact farther thus taking more time to travel. Making it the eldest. Part 2: The Atlantic Ocean Examine the map of the ages of the seafloor in the Atlantic Ocean. 8) Does the pattern of ages match your answer to Question 6? Revise your answer if necessary. Yes 9) Draw a line along the divergent boundary. 10) What is the age of the oldest rocks in the Atlantic Ocean? 180 million 11) Approximately how long ago did the Atlantic Ocean begin to form? 180 million Age, millions of yrs 180 154 132 120 84 48 33 10 0 Map of the ages of the seafloor in the Atlantic Ocean 12) Why should your answers to Questions #10 and #11 match? Revise your answers if necessary. Because if it formed 180 million years ago that means that it is 180 mil years old. 13) You are reading a proposal requesting money to search for evidence of a crater that caused a mass extinction on Earth 245 million years ago. The team is proposing to search a poorly explored area of the floor of the Atlantic Ocean between South America and northern Africa. Would you fund this project? Use the ages of the seafloor to support your answer. No because it has yet to reach that age, meaning there is no way to research this. Compare your answer of the last question to the answers of other groups.

3. The major plates that you should be able to identify include: i. North America plate ii. South America plate iii. Eurasian plate iv. African plate v. Indo-Australian plate vi. Antarctica plate vii. Nazca plate 4. There are also a number of minor plates, although you may not be able to find all of these based on topographic expression alone. i. Caribbean plate ii. Cocos plate iii. Philippine plate iv. Arabian plate v. Juan de Fuca plate vi. Scotia plate 5. There is one set of prominent topographic features on the sea floor that do not occur at plate boundaries. Isolated volcanic islands and linear chains of seamounts (undersea mountains) seem to result from rising blobs or plumes of hot mantle material. These are called hot spots, and the tracks they make across the sea floor are called hot spot tracks. Locate and label at least 3 of these hot spot tracks. Provide thoughtful answers to the following questions. 1. Do the general directions of plate motions indicated by your large arrows seem to make sense? Are there places where they do not seem to make sense? Explain.

I think they mostly make sense because it’s the way they departed from each other considering it started as pangea . To me the Phillipines plate is confusing. 2. Why is there a linear mountain chain along the western edge of South America? Because convergent plate created a subduction zone 3. Why does the Himalayan mountain system seem to “wrap around” northern India? India collided with Asia to form the mountains 4. What caused the Appalachian mountain range to form? Gondwana collided with North america 5. What 2 or 3 features on these maps not previously mentioned do you find most intriguing? Briefly describe them and speculate on their origin. 6. Compare your map of global Earth topography with the available maps of global topography on Mars and Venus. These can both be downloaded from Blackboard.