The world's water is in perpetual motion. The sun's heat evaporates water from the earth's oceans. These vapours are the stuff of clouds, which move inland.

The clouds drop some of their rain in the coastal regions. The main rain falls not on the plain but over the more mountainous regions of the world.

The rain runs off into streams which join to form rivers that bring the waters back to the sea. The cycle then starts all over again.

Not all of the streams flow over ground. The rain falling on the limestone regions percolates through the rock and finds its way to the rivers through subterranean passages.

CAVES ARE AN ESSENTIAL PART OF THE WATER CYCLE

Water Cycle

The sunlight heats the sea water, which evaporates to form clouds. As the cloud gets denser and darker, water droplets precipitate out from the cloud - it rains. Clouds move inland and rain falls on the high ground. The rain fills the rivers and these flow back into the sea. This is the water cycle.