A valley is a low area of land that is [...]

A river is a fresh watercourse that flows across the earth's surface into a larger body of water, usually a sea.

The ozone layer is a thin part of the Earth's atmosphere that absorbs almost all of the sun's harmful ultraviolet light.

An island is a body of land surrounded by water.  Islands are smaller than continents but bigger than isles.

A glacier is a large body of slowly moving ice. A glacier is made up of ice, snow, rock, and sediments.

A mountain is an elevated portion of the Earth's crust, [...]

A lagoon is a mass of water divided from larger bodies of water by a natural barrier.

An asteroid is a rocky object smaller than a planet and more prominent than a meteoroid that orbits the Sun.

The Solar System is a collection of planets, moons, asteroids, comets, moons, dust and gas that orbit the Sun.