The researchers studied deep layers of soil in northeast China to understand the difference between loess (wind-blown dust) and paleosol (ancient soil). They found that loess layers had less weathering and fewer clay coatings compared to paleosol layers. This suggests that the formation of loess soils is just as important as the reddish or yellowish paleosol layers. The researchers suggest using the terms "loessal paleosol" and "loessal paleosol sequence" to better describe the long-term weathering evolution in deep soil layers in pedology research.