A. Gravity is the driving force behind all mass movements: This statement is true. Gravity plays a crucial role in mass movements. It pulls objects downhill, causing them to move. Mass movements occur when the force of gravity overcomes the strength of the material holding the soil, rock, or debris in place.
B. Mass movements always create landslides: This statement is not true. While mass movements are often associated with landslides, not all mass movements result in landslides. Mass movements refer to the downslope movement of a mass of soil, rock, or debris under the influence of gravity. Landslides specifically involve the rapid movement of a large mass of material down a slope. So, while some mass movements can lead to landslides, others may involve slower and less dramatic movement.
C. Some mass movements are too slow to be seen: This statement is true. Some mass movements, such as creep, can occur at a very slow pace that is not easily noticeable. Creep is a slow movement of soil or debris downhill over an extended period of time. It may be difficult to observe this movement with the eye, as it happens gradually.
D. Mass movements are always downslope: This statement is generally true. Mass movements are typically associated with downslope movement. Gravity pulls objects downward, and mass movements occur when the force of gravity overcomes the resistance or strength of the material holding the soil, rock, or debris in place. However, it is important to note that mass movements can occur along curved or sloping surfaces, rather than a straight downward path.
In summary, mass movements are driven by gravity (statement A), they can be slow and not easily visible (statement C), and they generally involve downslope movement (statement D). However, not all mass movements result in landslides (statement B).