Changes to the Earth’s Surface: Erosion Adventures in Science (5.7B) S. Willingham, 2010

5.7B Earth’s surface is constantly changing and consists of useful resources. Recognize how landforms such as deltas, canyons, and sand dunes are the result of changes to Earth’s surface by wind water, and ice.

Introduction The surface of the Earth is always changing. Water and wind, snow and ice, all of these change the shape of the land. Wind can blow soil and small rocks to other places. Water can move soil and bits of rocks to new locations. Snow and ice can move down mountains, picking up soil and rocks as it moves. When any of these things happen, the shape of the land changes and new landforms are created. This process of moving soil and rocks to new places is called erosion.

Beaches Beaches are made of sand and small rocks that have been washed up or blown along the shore. The ocean water erodes sand from the bottom of the sea and deposits it on the beach. Rivers erode sediments along their path and drop them as they flow into the ocean. The wind is constantly changing the shape of sand dunes by eroding and moving the sand into new shapes. Water from waves or heavy rain keeps changing the shape of beaches.

Cliffs and Rocks The wind blows, the rain falls, and the waves crash against the cliffs along the shoreline. The soil that covers the rocks and cliffs is easily blown away. The ocean waves also pick up the soil and sand and move them away. Erosion, in the form of waves, wind and moving sediments, changes the landforms along the shoreline over a long period of time.

Canyons A canyon is a deep valley between cliffs, often carved from the landscape by rivers. Canyons are formed when moving water erodes and wears away the sides and bottoms of a river. The water erodes, or moves, the soil and rocks to new places along its path.

Glaciers A glacier is like a river of ice. When snow falls and the wind blows high up in the mountains, snow can pile up and turn into ice. The pile of ice becomes so heavy that it starts to move downhill. This moving ice is called a glacier. A glacier moves very slowly. The heavy ice breaks up rocks and makes big holes and u-shaped valleys in the land. When rain falls in these holes and valleys, a new lake or river is made. The moving glacier also picks up sediments and moves them to new places.

Dunes In sandy deserts and on sandy beaches, the wind blows the sand into large hills called dunes. The dunes in a desert or on the beach are constantly changing due to wind erosion.