The type of fault where rock moves downward at the fault line is called a normal fault.

Here's a breakdown:

* Normal Faults: These occur when the hanging wall (the rock block above the fault line) moves downward relative to the footwall (the rock block below the fault line). This type of fault is associated with tensional stress, where the Earth's crust is being pulled apart.

Let me know if you'd like to know more about other types of faults!