Activity 1.10 Plates and Mantle Convection (Grades 9-12)
Activity 1.10 is a cross-section of the outer layers of the Earth across the Mid-Atlantic Ridge and North American and Eurasian Plates. The questions test students' knowledge about plate tectonics. The North American and the Eurasian Plates are made of rigid mantle and oceanic and continental crust. The Mid-Atlantic Ridge is the boundary between the two plates. New oceanic crust is created at the ridge. The Mid-Atlantic Ridge is an example of a divergent plate boundary. Because the plates are diverging, the distance between North America and Europe is increasing. Convection currents in the mantle rise beneath the Mid-Atlantic Ridge and spread laterally along the base of the plates. The rocks flow back down into the mantle beneath subduction zones (not shown). Remember, the convection currents are in solid rock. Magma is present at very shallow depths immediately beneath the Mid-Atlantic Ridge, not at deeper levels in the convecting mantle.