Explain how the orientations of magnetic minerals (called magnetite) in the oceanic crust were used to prove that the ocean floor is spreading
2. Somewhere on Earth, a volcano is erupting right now (most are underwater!). Ocean floor spreading centers exhibit abundant volcanism, and the magma is produced by partially melting some asthenosphere.
a. Define magma, including its components.
b. Name and explain four major factors which affect magma viscosity such that it would become explosive rather than flow easily.
3. List THREE factors that affect the viscosity of magma (3 marks) and explain how each one affects viscosity. In what tectonic environment will volcanoes produce magma that is more viscous and why
4. Give examples of TWO famous volcanic sites/eruptions that occurred at each of these environments
a. Above a mantle plume
b. Above a subduction zone..What is the ultimate source of beach sand at Ocean Beach? CIRCLE: seawall I jetty I groin breakwater non CIRCLE: seawall jetty I groin breakwater none 31. Which of these coastal structures is installed specifically to prevent coastal erosion? 32. Which of these coastal structures is installed to create protected low-energy water for boats? 33. Which of these coastal structures results in bigger beaches in a particular location? 34. Which of these coastal structures results in increased erosion in a particular location? CIRCLE: seawall jetty I groin breakwater | none CIRCLE: seawall jetty I groin breakwater none