Final answer:
The downward movement of the hanging wall block relative to the footwall in an inclined fault plane characterizes a normal fault. This occurs due to extensional forces in the crust. Contrastingly, a reverse or thrust fault involves the upward movement of the hanging wall due to compressional stress.
Step-by-step explanation:
The blocks on either side of a fault are referred to as the walls, with the block above being the hanging wall and the block below being the footwall. When the hanging wall block moves downwards relative to the footwall along an inclined fault plane, this is called a normal fault. This type of fault occurs due to extensional forces where the earth's crust is being pulled apart. The movement opposite to a normal fault is seen in a reverse fault or a thrust fault, where the hanging wall moves upward due to compressional forces. Also, a thrust fault is a special type of reverse fault with a gentle dip, usually less than 30°. A strike-slip fault, in contrast, exhibits horizontal movement between the blocks.
A clear example of a normal fault can be seen from the Copper Creek Thrust Fault in Tennessee, where older rock formations are thrust over younger formations due to compressional stress resulting from tectonic collisions. This collisional force creates thrust faults, which are common in mountain belts.
Understanding the types of faults and their movements is fundamental in geology for interpreting the history of earth's formations and reconstructing past tectonic events. For example, if you find a fault cutting across layered rock, determining the age of the fault relative to the layers can provide insights into the geological history of the area.