Which feature characterizes a sand lens in relation to groundwater?

A sand lens is characterized by being a convex layer that contains fresh groundwater. This occurs when a layer of sand, which is typically more permeable than surrounding materials, collects and holds rainwater or surface water that infiltrates through the soil. The shape of the lens is usually concave on the bottom and convex on top, resembling an upside-down lens, which is where it gets its name.

The presence of fresh groundwater in a sand lens is significant, as it can contribute to the overall groundwater supply in an area. When the water table rises high enough, the water can saturate the sand, creating a localized pocket of fresh water that can be tapped for various uses.

In contrast, options referring to saltwater or polluted water do not represent the typical characteristics of a sand lens. Additionally, while a sand lens can affect aquifer behavior, it does not act as a restrictive layer; rather, it may enhance the flow of water due to its permeability. Understanding these features of sand lenses is crucial for groundwater management and environmental health.