A yawing fissure is a type of CHASM, which is an opening in the earth's surface that is large enough for a person to pass through. It is typically formed by erosion or tectonic activity and can be found in many different types of terrain. Yawning fissures are usually very deep and can be dangerous to traverse. They are often found in areas with steep cliffs or mountains, and can be used as a natural bridge between two sides of a canyon.