erosion

the process by which natural forces move weathered rock and soil from one place to another

sediment

Material that has moved by erosion is called sediment. Sediment may consist of pieces of rock or soil, or the remains of plants and animals.

deposition

Deposition occurs where the agents of erosion lay down (deposit) sediment.

gravity

Gravity is the force that pulls rocks and other materials downward, towards Earth.

mass movement

Mass movement is any one of several processes that move sediment downhill. Examples of mass movement include landslides, mudflows, slumps, and creep.

landslide

A landslide occurs when rock and soil slide quickly down a steep slope.

mudflow

A mudflow is the rapid downhill movement of a mixture of water, rock, and soil.

slump

A slump is a type of mass movement in which a complete mass of rock and soil suddenly slips down a slope.

creep

Creep is the very slow downhill movement of rock and soil.

runoff

As water moves over the land, it carries particles with it. This moving water is called runoff.

rill

As runoff travels, it forms tiny grooves in the soil called rills.

gully

A gully is a large groove, or channel, in the soil that carries runoff after a rainstorm. When many rills flow into each other, they get larger and form a gully. Gullies only contain water during a rainstorm and for a short time after it rains.

stream

A stream is a channel along which water is continually flowing down a slope. Gullies join to form a stream.

tributary

A tributary is a stream or river that flows into a larger river.

watershed

A drainage basin that supplies water to a river and its tributaries.

valley

A low area of land between hills or mountains, typically with a river or stream flowing through it.

waterfall

A cascade of water falling from a height, formed when a river or stream flows over other rock. Waterfalls may occur when a river meets an area of hard rock that is next to another area of softer rock. The soft rock wears away faster than the hard rock, an

flood plain

The flat, wide area of land along a river is a flood plain.

meander

A meander is a loop-like bend in the course of a river.

oxbow lake

An oxbow lake is a meander that has been cut off from the river.

delta

Sediment deposited where a river flows into an ocean or lake builds a landform called a delta.

alluvial fan

An alluvial fan is a wide, sloping deposit of sediment formed where a stream leaves a mountain range.

groundwater

Groundwater is water from rain or snow that soaks into soil and into cracks and spaces in rock layers.

stalactite

A deposit that hangs like an icicle from the roof of a cave is known as a stalactite.

stalagmite

Slow dripping of groundwater builds up a cone-shaped stalagmite from the cave floor.

karst topography

A landscape that has a lot of deep valleys, caverns, and/or sinkholes. Karst topography occurs in rainy areas that have a layer of limestone near the surface. Whenever it rains, the water doesn't flow away -- it wears holes in the limestone because the li

glacier

A glacier is any large mass of ice that moves slowly over land.

continental glacier

A continental glacier is one that covers much of a continent or large island.

ice age

An ice age is a time in which continental glaciers cover large parts of Earth's surface.

valley glacier

A valley glacier is a long, narrow glacier that forms when snow and ice build up high in a mountain valley.

plucking

As a glacier flows over land, it picks up rocks in a process called plucking. When the weight of the glacier breaks rocks apart and the rock fragments freeze to the bottom of the glacier, the rocks are carried onward when the glacier moves.

till

The mixture of sediments that a glacier deposits directly on the surface is called a till.

moraine

The till deposited at the edges of a glacier forms a ridge called a moraine. A moraine forms where a glacier deposits a mound or a ridge.

kettle

A kettle is a small depression that forms when a chunk of ice is left in glacial till. When the ice melts, the kettle remains. Kettles often fill with water, forming small ponds or lakes called kettle lakes

headland

A headland is a part of the shore that sticks out into the ocean.

beach

A beach is an area of wave-washed sediment (usually sand) along a coast.

longshore drift

As waves repeatedly hit a beach, some of the beach sediment moves down the beach with the current, in a process called longshore drift.

spit

A spit is a beach that projects like a finger into the water. Spits are created by deposition by longshore drift. They occur where a headland or other obstacle interrupts the longshore drift.

deflation

Deflation is the process by which wind removes surface materials. Wind causes erosion mainly by deflation.

sand dune

When wind meets an obstacle, the result is usually a deposit of windblown sand called a sand dune.

loess

Sediment that is smaller than sand, such as particles of clay and silt, is dropped far from its source in large deposits. This fine, wind-deposited sediment is called loess. Loess helps to form fertile soil.