about weathering, mass movement and erosion.

風化是指岩石分解成土粒的過程
soil erosion是指風化物(那些土粒)被帶走使泥土貧瘠
塊體移動作用 mass movement，是指地面上風化了的岩層、岩體、岩屑或土體，在重力（即地心吸力）作用下，並在一定水分的參與下，發生不同形式、不同速度的位置下移，形成一系列獨特的重力地貌。
即是,風化是erosion & mass movement的先決條件之一

Weathering and erosion are quite similar, whereas mass movement is a completely different aspect but it could be link to soil erosion.

Erosion can be put into two types:
1. Chemical weathering
2. Mechanical weathering

Erosion is the process where materials such as rocks got eroded/cut.
Weathering is the actual process of erosion.

Mass movement includes mudflow, debris flow and avalanches etc.
The difference between mudflow and debris flow is the difference in the size of the material being carried.
The materials carry by a mudflow are finer than the ones of a debris flow.

Cause of Mass Movement:
Mass movement can be caused by soil erosion or the removing of vegetation in an area. The root system of plant helps to hold the soil together, making the land stable. It also helps to absorb excess water.
Mass movement takes place when the water content in the soil is more than its capacity, causing the soil to loose its cohesion and the particles become unstable and collapse.