Which of the following is a common effect of erosion?

Erosion is a natural process that wears away the Earth's surface, often resulting in the removal of the top layer of soil, commonly known as topsoil. This layer is crucial for plant growth as it contains a rich mix of organic matter and nutrients. When erosion occurs, primarily due to water, wind, or human activities, the topsoil can be carried away, leading to decreased soil fertility and productivity in affected areas.

Loss of topsoil can have significant impacts on agriculture, ecosystems, and landscapes, often resulting in reduced crop yields and increased vulnerability to drought or further erosion. In contrast, the other options provided indicate processes that either mitigate or alter the environment in ways that do not align with the primary characteristic of erosion itself. For instance, while deltas can form from sediment deposition, they are not a direct effect of erosion but rather of sediment transport and deposition processes. Thus, the primary and most direct consequence of erosion in the context of this question is indeed the loss of topsoil.