Step 1: Understanding the Concept:
This question asks for the specific term for a type of water erosion characterized by the removal of a thin, uniform layer of soil over a large area.
Step 2: Detailed Explanation:
Let's define the forms of erosion listed:
(A) Sheet erosion: This occurs when runoff flows as a shallow, non-concentrated layer, or "sheet," across the soil surface. This thin layer of water has enough energy to detach and transport the finest soil particles. The result is the gradual and uniform removal of a thin layer of topsoil from a large area of sloping land. Because it's uniform, it can be insidious and difficult to notice until a significant amount of productive topsoil has been lost. The description "removal of a fairly uniform layer of soil" is the classic definition of sheet erosion.
(B) Splash erosion: This is the erosion caused by the impact of individual raindrops on bare soil. The impact dislodges soil particles and splashes them a short distance. It is the first stage of the erosion process, but it does not in itself remove a uniform layer over a large area.
(C) Coastal erosion: This refers to the wearing away of land and the removal of beach or dune sediments by wave action, tidal currents, and wind along a coastline.
(D) Geological erosion: This is the natural, slow erosion process that occurs without the influence of human activities. It is responsible for shaping landscapes over geological time. The question refers to erosion by rainfall and runoff, which is usually discussed in the context of accelerated (human-induced) erosion, although the mechanism is the same. "Sheet erosion" is the specific mechanism described.
Step 3: Final Answer:
The removal of a uniform layer of soil by non-concentrated runoff is known as sheet erosion. Therefore, option (A) is the correct answer.