* Water: The most common answer. Rivers, streams, and waterfalls are all formed by water flowing downhill from mountains.
* Lava: Volcanoes are mountains, and they can erupt with molten lava flowing down their slopes.
* Rocks and Debris: Gravity pulls rocks and other debris down mountainsides, creating landslides and rockfalls.
* Snow and Ice: Glaciers form in mountainous areas and slowly flow downhill.
Let me know if you want to try another riddle!
