fissure A fissure is a crack in a rocks. A volcanic fissure is one from which lava erupts.

fold mountains Fold mountains are a type of mountain range that is formed when two continental plates collide (or one continental plate colliding with an oceanic plate). The colliding crust is compressed and pushed upwards (uplifted), forming mountains. For example, the Himalayas were slowly formed when the Indian plate collided with the Asia-European plate millions of years ago.