Assignment task: Using Google earth, Motion across the mid-Atlantic ridge: the South American plate vs. the African plate. Turn on the "Seafloor age" and the "Plate Boundary" Google Earth (GE) layers. The "Seafloor age" layer shows the ages of volcanic rocks that have erupted and cooled to form the ocean floor. Focus on the Atlantic Ocean. Note that the age bands generally run parallel to the spreading ridges. Seafloor age is a critical piece of evidence for plate tectonics.
Q1. How many million years (abbreviated Ma) does each colored band represent?
Q2. On average, continental crust is 2 billion years old; the oldest rocks are 3.8 billion years old, and some of the grains in those rocks are even older. What is the age of the oldest seafloor? On average, which is oldest - the continents or the ocean basins?
Q3. Find the South American plate, the African plate, and the Mid-Atlantic Ridge that marks the boundary between them. What happens to the age of the seafloor as distance increases away from the Mid-Atlantic Ridge?
Q4. Is crust being created or destroyed at this plate boundary (and other spreading ridges)?
Q5. Is this plate boundary divergent, convergent, or transform?