A mountain is an area of much higher land than its surroundings. There are two kinds of mountain: volcanic mountains, which are made of of a single peak, and mountain ranges, that have many peaks, and which stretch in a long line.

Quite often volcanic mountains stand up out of the top of mountain ranges, making them some of the highest mountains in the world. The highest mountains in the Andes are like this.

Mountain ranges were formed when two parts of the Earth's crust pushed against one another, crumpling up the edges where they met. This happened very slowly - about 2cm a year - but it happened over millions of years. In some places it is happening today.

How would you notice if a mountain range was forming today? You would not see it move, but you feel it move! That is because the rocks are hard and brittle, and so they don't crumple up easily. Instead they stand up to the crumpling force for many years, then move in a quick snap. That snap is an earthquake - and you certainly feel earthquakes!