The surface of the world is in constant motion. Land is thrust upwards to form mountains and land is sucked back under the crust of the earth. Sometimes the events that shape the earth's surface are explosive and readily observable, like volcanoes and earthquakes, but often the events take millions of years to shape the earth. Erosion – whether by wind, water or ice – is a shaping force that takes its time, but the results can be just as dramatic as an exploding volcano.
The Grand Canyon
The most famous work of erosion is probably the Grand Canyon in Arizona in the United States. The Colorado River carved out the canyon over millions of years as it snaked its way from the Rocky Mountains to the Gulf of California. What is left is a huge canyon that exposes layer upon layer of sedimentary rock. At its deepest it is a mile (1.6km) down, 277 miles (446km) long and 18 miles (29km) wide.
One of the most famous English landscapes was formed on the south Dorset coast by erosion from the sea. The harder limestone has withstood the coastal erosion, but the softer rock was worn away to leave the “door.” Over time, the top of the arch will erode away, leaving a pillar known as a “sea stack” standing in the English Channel.
This dramatic rock that rises out of the flat desert in central Australia was once much larger but over time it has been weathered and worn down by rain and wind. The sedimentary rock was formed by layers of sand being pressed down on top of each other over time. Huge geological forces eventually spun the rock 90 degrees so the layers now go from top to bottom. The erosion that has battered the rock has led to some parts eroding faster than others, leaving stripes or “ribs” in the surface of the rock.
The Norwegian fjords
The Norwegian fjords are a great example of the eroding power of glaciers. They were formed when huge veins of ice pushed their way through rock over millions of years, carving out steep-sided valleys. When they retreated the valleys allowed water from the sea to enter. The longest fjord in Norway is Sognefjord at 127 miles (204km).