Final answer:
In geography, the fastest type of mass movement is a debris flow or mud flow, which can sweep up large objects and cause serious damage, such as the blocking of bridges and flooding.
Step-by-step explanation:
The type of mass movement in which material travels fastest is typically associated with debris flows or mud flows. These rapid movements can occur when slope material becomes saturated with water, transforming the debris into a fast-moving slurry of rock, mud, and other materials that may sweep up trees, houses, and vehicles. This can lead to blocking of bridges and cause flooding along its path by obstructing tributaries.
Debris flows and mud flows differ from slower forms of mass movement, such as soil creep or the gradual settling of sediment in a lake, which can occur at terminal velocities of a few micrometers per second and take days to reach a resting place. In contrast, debris flows can rush down a slope at speeds exceeding tens of meters per second, dependent on the volume of water, slope angle, and material composition.
An example of this rapid movement took place in 2014, when the Oso mudslide in Washington State occurred, with parts of the slide traveling at approximately 60 miles per hour (97 kilometers per hour), demonstrating the devastating speed and power of these natural events.