“…Depositional ages of this sequence span from ∼22 to ∼6 Ma and a recent study extended the bottom age of this sequence back to 25 Ma (Qiang et al, 2011). At this time, debates exist about whether "loess sediments" older than 6 Ma are eolian in origin or at least whether they were also affected by fluvial processes after deposition (Ding et al, 1998;Sun et al, 1998;Guo Z. T. et al, 2001;Alonso-Zarza et al, 2009). However, most researchers agree that loess sediments younger than 6 Ma are eolian with little modification from fluvial processes (Ding et al, 1998;Sun et al, 1998;An et al, 2001;Lu et al, 2001).…”