EARTH’S CHANGING SURFACE

Weathering

Breakdown of rocks into smaller pieces

Erosion

Transportation of weathered material by wind, water, or ice

Mechanical Weathering

Physical breakdown of rocks into smaller fragments

Abrasion

Wearing away of rocks by friction and impact

Ice Wedging

Process of water freezing and expanding in cracks, breaking rocks apart

Chemical Weathering

Breakdown of rocks through chemical reactions

Oxidation

Chemical reaction between oxygen and minerals in rocks

Permeable

Ability of soil or rock to allow water to pass through

Soil

Mixture of minerals, organic matter, water, and air

Bedrock

Solid rock beneath the soil and weathered material

Humus

Decomposed organic matter in soil

Fertility

Ability of soil to support plant growth

Loam

Soil with balanced amounts of sand, silt, and clay

Soil Horizon

Distinct layer of soil with different properties

Topsoil

Uppermost layer of soil, rich in organic matter

Subsoil

Layer of soil beneath the topsoil

Litter

Layer of dead leaves and organic material on the soil surface

Decomposer

Organism that breaks down dead organic matter

Mass Movement

Downslope movement of weathered material due to gravity

Runoff

Water that flows over the land surface

Stream

Flowing water in a channel

Tributary

Small stream that flows into a larger stream or river

Flood Plain

Flat area along a river that is prone to flooding

Meander

Curve or bend in a river

Oxbow Lake

U-shaped lake formed when a meander is cut off from the main river

Alluvial Fan

Fan-shaped deposit of sediment at the base of a mountain

Delta

Triangular deposit of sediment at the mouth of a river

Groundwater

Water stored beneath the Earth's surface

Stalactite

Hanging mineral deposit formed on the ceiling of a cave

Stalagmite

Mineral deposit that rises from the floor of a cave

Karst Topography

Landscape characterized by sinkholes, caves, and underground drainage

Beach

Sandy or pebbly shore along a body of water

Spit

Narrow strip of land extending into a body of water

Sand Dune

Mound of sand formed by wind

Loess

Wind-blown deposit of fine-grained sediment

Glacier

Large mass of ice that moves slowly over land

Continental Glacier

Ice sheet that covers a large area of land

Ice Age

Period of time when glaciers covered much of the Earth's surface

Valley Glacier

Glacier that forms in a mountain valley

Plucking

Process by which a glacier picks up rocks and sediment

Till

Unsorted sediment deposited by a glacier

Moraine

Ridge or mound of till deposited by a glacier

Kettle

Depression formed when a block of ice is left behind by a glacier