The gradient in bed load is mostly made up mostly of gravels and sands, broken down versions of larger boulders and rocks, which are most commonly found in mountainous areas. Streams with low gradients cannot carry bed load down stream because it moves slowly and without much force. Gravels and sands couldn't move downstream because the water flow isn't strong enough to move them or to keep them in motion.
I would say earthquake but I dont know if its looking for something more specific life a fissure or fault. Anyways its geology related because one of the causes is techtonic plates moving.
Answer: 1 : knowledge about the natural world that is based on facts learned through experiments and observation. 2 : an area of study that deals with the natural world (as biology or physics)
