Streams erode at their banks, carrying sediments and soluble ions in their waters. Sediments can be carried as a:
Rainwater combines with carbon dioxide to form carbonic acid. This acid seeps into the ground through cracks and pores. This acid then becomes what is called groundwater. Groundwater is able to form underground caves by wearing away at soil. When the roof of a cave collapses, a sinkhole is formed. Groundwater carries minerals in solution and the minerals can be deposited as stalagmites and stalactites. The joining of a stalagmite and a stalactite is called a column. Caves form when groundwater travels along small cracks over an extended period of time. The groundwater slowly dissolves and carries away the solid rock which enlarges cracks and forms caves.
When a wave hits the ground, the inshore part hits first and is slowed down. This causes the curving of the waves known as refraction. Wave refraction can:
Waves can also create:
Waves spread sediments along a coast in order to create a beach. Waves have higher energy during winter than in summer. Sand is pushed onto shore in the summer, and pulled offshore during winter. Sometimes spits are formed, which are areas of sand that extend land masses into water. Shores may also be lined with barrier islands, small pieces of land that act as a defense against storms. People try to protect shores by making:
Wind is able to transport small particles over long distances. Wind transports both bed and suspended loads, with sand-sized particles traveling via bed loads. These bed loads are made of sand-sized particles which move by saltation.
When the wind blows away smaller, finer particles, the desert surface is rockier, causing the ground to subside (known as deflation). This leaves behind desert pavement, or rocky, pebbled surfaces. Grains are moved by the wind and hit other surfaces, eroding the surface in the form of abrasion. Surfaces that have been worn away at by grain are called ventifacts.
Rocks in deserts often gain a dark coating called desert varnish. This coating is made by manganese and iron oxides, which react with other substances that wind transports. Steady winds can form sand dunes, which are slopes of sand with a slip face, or flatter face on the opposite side. Silt and clay deposited layer over layer is called loess. Clay on the ocean floor is brought to the ocean by the wind.
Wind can also bring silts and clays to the ocean, forming fine-grained mud in the deep ocean. When these particles are deposited on the water’s surface by wind, they eventually settle to the ocean floor in the form of green, brown or red clays.
Glaciers have the power to erode at rock through abrasion and plucking. Plucking is when water seeps into the cracks between rocks and freezes pushing the rocks outward. As the glacier moves the rocks create long parallel grooves called glacial striations. When glaciers cut through a v-shaped valley they widen it making it a u-shaped valley. A hanging valley forms when a main glacier cuts off a tributary glacier and creates a cliff.
Glacial erratics are rocks that are carried by glaciers and are eventually dropped. A glacial till is a pile of the bits of rock that the glacier had been carrying. Linear rock deposits are called moraines.
Varves are former where lakes are covered by ice. Dark sand sinks to the bottom of the lake and then when the ice melts a layer of light sand is deposited.
Gravity causes erosion because of mass weathering. Weathered material falls from a cliff because there is nothing to hold it in place. Rocks falling to the base of a cliff make a taulus slope. Landslides occur when falling rocks hit other rocks causing them to fall as well. When there is high precipitation, a mudflow will be created. A lahar is a mudslide on a volcano. Slump moves materials along a curved surface. Creep is a gradual movement of soil downhill. Several factors increase the chance of a landslide.