What is a hill of sand built by wind at the coast referred to as?

A hill of sand built by wind at the coast is referred to as a coastal sand dune. These formations occur when windblown sand is deposited in areas where the vegetation is sparse, allowing the sand to accumulate and form dunes. Coastal sand dunes play a crucial role in protecting shorelines from erosion, providing habitats for various species, and acting as natural barriers against storms and high winds.

The formation of coastal sand dunes is influenced by factors such as wind direction, sand supply, and the presence of vegetation, which stabilizes the sand and helps maintain the structure of the dunes. Such processes create dynamic landscapes that can shift over time as they respond to changes in environmental conditions.

While other options refer to different coastal processes or features, they do not accurately describe the sand formations created by wind. For example, afforestation pertains to planting trees and does not relate to sandy coastal features. Rip rap is a type of rock or concrete used to protect shorelines from erosion, and tide refers to the rise and fall of sea levels caused by gravitational forces. Thus, coastal sand dune is the only term that accurately describes the hill of sand formed by wind at the coast.