What is the probable cause of spreading of the seafloor at the Mid-Atlantic Ridge? A. the movement of continents, followed by underwater earthquakes B. the movement of tectonic plates with an accompanying outpouring of magma C. the eruption of underwater volcanos and an outpouring of lava D. the movement of ocean currents due to the rotation of Earth and its axis

The theory of plate tectonics is fundamental to understanding many geological processes, including seafloor spreading. Tectonic plates are massive slabs of Earth's lithosphere that fit together like a jigsaw puzzle. They float on the semi-fluid asthenosphere and are constantly moving due to convection currents from the molten rock beneath. This movement is responsible for the formation, destruction, and interaction of crustal features. Just like a big conveyor belt, these plates can move toward or away from each other. Areas where plates move apart are known as divergent boundaries. Seafloor spreading, specifically at the Mid-Atlantic Ridge, is a classic example of this process.

The Mid-Atlantic Ridge is one of the most significant features on Earth linked to seafloor spreading. This underwater mountain range runs down the center of the Atlantic Ocean. It is a divergent plate boundary between the Eurasian Plate to the north and the North American Plate, and the African Plate to the south and the South American Plate. At this boundary, the plates are slowly drifting apart. As they separate, magma from the mantle wells up to fill the gap, cools, and solidifies to form new oceanic crust. Over time, this process pushes the plates further apart, constantly renewing the seafloor.

The movement of tectonic plates is the primary mechanism behind seafloor spreading and many other geological phenomena. Tectonic plates move due to the convection currents in the mantle, which drive the plates apart at divergent boundaries like the Mid-Atlantic Ridge. When the plates move, magma rises from below the Earth's crust to fill the gap. This magma cools and forms new oceanic crust. This geodynamic process explains why seafloor spreading occurs specifically at mid-ocean ridges and clarifies why the answer to the original exercise is option B. Elements like underwater volcanoes and lava are relevant but secondary factors in this continuous cycle.