Definitions
- archipelago
- a group of islands
- basin
- an area of land drained by a given river and its branches; area of land surrounded by lands of higher elevations
- bay
- part of a large body of water that extends into a shoreline, generally smaller than a gulf
- canyon
- deep and narrow valley with steep walls
- cape
- point of land that extends into a river, lake, or ocean
- channel
- wide strait or waterway between two landmasses that lie close to each other; deep part of a river or other waterway
- cliff
- steep, high wall of rock, earth, or ice
- continent
- one of the seven large landmasses on the Earth
- delta
- flat, low-lying land built up from soil carried downstream by a river and deposited at its mouth
- divide
- stretch of high land that separates river systems
- downstream
- direction in which a river or stream flows from its source to its mouth
- escarpment
- steep cliff or slope between a higher and lower land surface
- glacier
- large, thick body of slowly moving ice
- gulf
- part of a large body of water that extends into a shoreline, generally larger and more deeply indented than a bay
- harbor
- a sheltered place along a shoreline where ships can anchor safely
- highland
- elevated land area such as a hill, mountain, or plateau
- hill
- elevated land with sloping sides and rounded summit; generally smaller than a mountain
- island
- land area, smaller than a continent, completely surrounded by water
- isthmus
- narrow stretch of land connecting two larger land areas
- lake
- a sizable inland body of water
- lowland
- land, usually level, at a low elevation
- mesa
- broad, flat-topped landform with steep sides; smaller than a plateau
- mountain
- land with steep sides that rises sharply (1,000 feet or more) from surrounding land; generally larger and more rugged than a hill
- mountain peak
- pointed top of a mountain
- mountain range
- a series of connected mountains
- mouth 
- (of a river) place where a stream or river flows into a larger body of water
- oasis
- small area in a desert where water and vegetation are found
- ocean
- one of the four major bodies of salt water that surround the continents
- ocean current
- stream of either cold or warm water that moves in a definite direction through an ocean
- peninsula
- body of land jutting into a lake or ocean, surrounded on three sides by water
- physical feature
- characteristic of a place occurring naturally, such as a landform, body of water, climate pattern, or resource
- plain
- area of level land, usually at low elevation and often covered with grasses
- plateau
- area of flat or rolling land at a high elevation, about 300 to 3,000 feet (90 to 900 m) high
- reef
- a chain of rocks, coral or sand at or near the surface of the water
- river
- large natural stream of water that runs through the land
- sea
- large body of water completely or partly surrounded by land
- seacoast
- land lying next to a sea or an ocean
- sound
- broad inland body of water, often between a coastline and one or more islands off the coast
- source
- (of a river) place where a river or stream begins, often in highlands
- strait
- narrow stretch of water joining two larger bodies of water
- tributary
- small river or stream that flows into a large river or stream; a branch of the river
- upstream
- direction opposite the flow of a river; toward the source of a river or stream
- valley
- area of low land usually between hills or mountains
- volcano
- mountain or hill created as liquid rock and ash erupt from inside the Earth
