I have never known gravity to have "stages", though, I suppose tha answer could be:
1. water runs in a river
2. gravity keeps the water in the riverbed.
3. the river bed becomes a cliff
4. gravity's force causes the water to fall, not just keep going. (let the force be with you)
5. it keeps falling because of gravity, and hits the bottom of the water fall because of gravity.
I hope this is right, though I TOTALLY doubt it lol. If you find out the answer, please let me know :)
