Making Mountains

Some mountains form when the big slabs of rock—called tectonic plates—that make up the Earth’s crust crash into each other. Over millions of years, the sheets of rock push up and over one another, creating the mountain. Others form when vents in the Earth’s surface erupt and spew lava out onto the ground. The lava piles up and cools. Over millions of years, the many layers of hard lava become a mountain. Mountains are on every continent. The longest mountain range is over 40,000 miles long—and 90 percent is under the ocean! Called the Mid-Ocean Ridge, it wraps around the globe like the seams of a baseball. The longest aboveground mountain range is the Andes. Running along the entire west coast of South America through seven different countries—including Argentina, Chile, and Colombia—it’s 4,700 miles long. Mount Everest, on the border of Nepal and China in Asia, is the highest mountain above sea level in the world. Towering at just over 29,000 feet it would take almost 5,000 grown men stacked on top of each other to reach that high.