Here's why:

* Building mountains: Plate tectonics creates mountains through collisions (convergent boundaries) or the upwelling of magma (divergent boundaries).

* Forming valleys: Plate movements can also lead to the formation of valleys, especially through the process of erosion caused by rivers and glaciers.

* Creating volcanoes: Volcanic eruptions, driven by tectonic activity, build up landforms like volcanoes and plateaus.

* Earthquakes: Earthquakes, another result of tectonic activity, can dramatically alter landscapes by creating faults, shifting land, and triggering landslides.

While other forces like erosion, weather, and biological processes are important in shaping landscapes, tectonics provides the fundamental framework upon which these forces act.