Answer :
Debris Flow is the most common type of mass movement in the San Gabriel Mountains.
Explanation:
It is the one of geological process due to which soil, fragmented rocks flows down mountainside, making channels, also takes object along with it in their path. That gives rise to formation of thick muddy deposits over the surface. this happens when the slope reaches the peak of slope saturation point, huge debris flow begins off the mountains, it destroys everything, causing hazard to local population. Due to excessive rainstorms followed by fires, the soil unrestricted and leads to debris flow.