Here's why:
* Gravity pulls everything towards the center of the Earth. This means that anything on a slope will experience a force pulling it downwards.
* The steeper the slope, the stronger the force of gravity pulling the rocks downhill. This is why rocks on steep cliffs are more likely to fall than rocks on gentle slopes.
* Other factors can contribute to rock falls and rolls, like:
* Weathering: Rain, frost, and temperature changes can break down rocks, making them more likely to fall.
* Earthquakes: Earthquakes can shake loose rocks and cause them to fall.
* Human activity: Construction, mining, and other activities can destabilize slopes and lead to rock falls.
So, while other factors can play a role, gravity is the primary force that causes rocks to fall or roll downhill.
