El Capitan

In Yosemite valley, there are many towing granite cliffs that line the valley. There is one in particular that stands out, El Capitan. El Capitan is a sheer rock face that stands over 3,000 feet tall, making it the tallest exposed vertical face of granite in the world. This wall started forming around 220 million years ago when the north american tectonic plate collided with a neighboring pacific tectonic plate. Molten rock seeps through the earth's crust forming an ancient chain of volcanoes. Some of the magma erupted, but most of it remained underground and cooled over many eons. This formed granite, a rock as strong as steel and twice as hard as marble. This reserve of granite was 300 miles long and 70 miles long. Around 10 million years ago tectonic pressures resulted in a fault system along the western edge of the granite, forcing some granite to the surface, creating the recognizable rock of Yosemite. The Merced river, another important feature, over millions of years, shaped Yosemite Valley. It eroded away the weaker rock between El Capitan and the earth's surface. During the Ice age, slow moving masses of ice further carved out the valley floor, and created El Capitan. The ice age got rid of loose rocks on El Capitan, creating a very vertical wall.