What physical feature defines gullied land?

The defining feature of gullied land is the visible erosion that creates channels or depressions in the landscape. When we say you have to "jump over it," this highlights the physical manifestation of gullies: they are often deep, trench-like features formed by the concentration of water flow that has eroded the soil over time. This physical presence is stark and indicates significant soil movement and degradation, typically resulting from water runoff or heavy rainfall.

The other options do not accurately define gullied land. A visible surface crust might be present in other soil conditions, but it does not indicate gully formation. The presence of clay layers might contribute to soil properties but is not unique to eroded lands. Flat topography, on the other hand, suggests stability and very little erosion, which contrasts with the characteristics of a gully. Thus, the characteristic nature of gullied land is encapsulated in the notion that it is a topographical feature requiring an effort to traverse, such as having to jump over it.