Divergent Plate Boundary: Where Earth's Crust Pulls Apart — Passage and Quiz

The Earth's crust is made up of large, moving pieces called tectonic plates. Where these plates pull apart, they form divergent boundaries. These boundaries create some of the most dramatic landscapes on Earth, including rift valleys on continents and mid-ocean ridges under the sea.

One of the best-known examples is the Mid-Atlantic Ridge, an underwater mountain chain running down the middle of the Atlantic Ocean. Here, two plates move away from each other, allowing magma to rise from below. As the magma cools, it forms new crust, slowly widening the ocean floor. Because of this, the Atlantic Ocean grows about 2.5 centimeters wider each year—a process called seafloor spreading.

On land, divergent boundaries create deep valleys. The Great Rift Valley in East Africa is a massive crack in the Earth’s crust where the African Plate is splitting apart. Over millions of years, this rift could grow so wide that a new ocean may form.

At these boundaries, earthquakes and volcanic eruptions are common as the crust stretches and breaks. The new crust formed at mid-ocean ridges is younger and warmer, making it less dense than older seafloor. This movement helps drive the slow but powerful cycle of plate tectonics, reshaping our planet over time.

By studying divergent boundaries, scientists learn how oceans expand and continents split—key evidence for understanding Earth’s ever-changing surface.

Fun Fact: Iceland is literally splitting in half! The Mid-Atlantic Ridge runs right through the island, pulling it apart at about 2.5 cm per year (the width of a Lego brick). In Thingvellir National Park, you can stand between two continents—one foot on the North American Plate and the other on the Eurasian Plate!