Amass of falling and tumbling rock, debris, and soil traveling at a high velocity owing to the presence of ice or water is a rockfall. mudflow. debris avalanche. landslide.

Due to the fact that you said ice or water I'm thinking a mudflow but it could be a landslide considering the rock and debris but I'm almost certain its a mudflow because mudflows happen at high velocities, or quickly than all the other options you have there.

10 neutrons is the answer

It's true it didin't work becouse britain continued trading with it's colonies and the system hurt economies of the countries that used it