Final answer:
Rock debris that gathers at the base of steep inclines due to gravity is known as talus. This geological feature forms from the weathering and erosion of rock, and can be influenced by events like earthquakes and volcanic eruptions.
Step-by-step explanation:
The rock debris which accumulates at the base of steep slopes by gravitational action is called talus. This accumulation process happens when fragments of rock break off from the high ground, often due to physical and chemical weathering, and descend due to gravity. Over time, talus can form distinctive piles or slopes at the base of cliffs or mountainsides.
Landslides and other erosional processes can also contribute to the formation of talus. For instance, an earthquake might trigger the release of rock and soil on a weakened slope, creating additional material that accumulates at the base. Moreover, when a volcano erupts, it can produce loose ash and other materials that eventually settle and create a talus formation.