What should be marked during the diagnosis of buried soils?

The correct answer is to mark all layers but no classification during the diagnosis of buried soils. This approach is essential because buried soils can have complex stratigraphy, and each layer may provide valuable information regarding the soil's historical formation processes, development, and changes over time. By marking all layers, the evaluator can capture variations in texture, structure, color, and other properties that can inform about past environmental conditions and soil management impacts.

Focusing solely on one layer or only layers with organic content misses the opportunity to understand the entire profile's evolution and ignore the significance of other layers that may not show organic content but are crucial to the soil's history. This comprehensive examination allows for a more accurate and holistic assessment of the soil's characteristics, which is vital in soil judging practices. Therefore, documenting all layers without classifying them promotes a thorough description that can later aid in understanding the soil's functionality and its role in the landscape.