Here's why:

* Geomorphology is the study of landforms and the processes that shape them.

* Rock movement down slopes is a key process in landform development, known as mass wasting. This includes processes like landslides, rockfalls, debris flows, and soil creep.

* The geomorphic system encompasses all the interacting factors that contribute to the formation and evolution of landscapes. These factors include:

* Climate: Weathering, erosion, and deposition are influenced by climate.

* Geology: The type of rock and its structure influence how it erodes.

* Tectonics: Plate movements create mountains and valleys, setting the stage for erosion.

* Biological processes: Plants and animals can influence weathering and erosion.

* Human activities: Development, agriculture, and other activities can alter slopes and impact erosion.

In essence, when rock material moves down a slope, it becomes part of the dynamic interplay of forces within the geomorphic system that shapes the Earth's surface.