What denotes the presence of a normal fault?

A normal fault is characterized by a specific movement of geological blocks due to extensional stress in the Earth's crust. In this type of fault, the hanging wall block moves downward relative to the footwall block. This movement reflects tectonic forces that are pulling the blocks apart, leading to the separation and downward movement of the hanging wall.

This concept is crucial in understanding geological processes, as normal faults are commonly associated with divergent boundaries where tectonic plates move away from each other. The presence of a normal fault indicates that the Earth's crust is being extended, which can create rift valleys and other geological features over time.

The other options describe different types of fault movements. For example, blocks moving together would indicate a reverse fault, where one block is pushed up over the other due to compressional stress. Lateral movement of blocks describes a strike-slip fault, where two blocks slide past each other horizontally. Lastly, blocks stacking on top of one another could relate to convergent boundaries and reverse faults but do not pertain to the characteristics of a normal fault. Understanding these dynamics is essential for interpreting geological formations and the forces at play in a given region.