Which type of soil has not been disturbed for at least ten years?

The term "banked soil" refers to soil that has been intentionally built up or packed, often over a lengthy period, and hasn't been disturbed or altered for at least a decade. This method of soil creation allows for improved stability and ensures the integrity of the soil profile against erosion and other environmental factors.

In contrast, loamy soil is a mixture of sand, silt, and clay that has optimal growing conditions but doesn't indicate a lack of disturbance over time. Clay soil, though sometimes undisturbed, does not specifically denote a time frame and is characterized by its fine texture and water retention properties. Fill soil consists of material (soil, rock, etc.) that has been placed in a location to raise the ground level or as part of a construction project, which inherently means the soil has been disturbed.

Thus, the correct identification of banked soil aligns with the requirement that it has remained untouched for a minimum of ten years.