Answer. These are the most common types of mountain forms on Earth. When two continental plates move towards each other and the rocks or debris etc. Start folding into a structure which leads to the formation of fold mountains. These are formed through an orogeny process which takes several years. These mountains are formed at convergent plate boundaries or continental collision zones or compression zones. The stress in these zones due to move towards each other leads to mountain formation. These can be very old, old, and young fold mountains based on their period of origin and simple or complex based on their structure of folding. For example, the world-famous mountain ranges, the Himalayas, the Andes, the Alps are examples of fold mountains.