Figure 1

Digital elevation model of the Sanjiang Plain, which was generated by Zhenqing Zhang using ArcGIS 10.0.
The solid triangles and circles in black color indicate the sampling sites and the sites of peat cores with based ages mentioned in the text respectively. See Table 2 for sites information and references. In inset figure, the current northern limit (dashed line) of the East Asian Summer monsoon with its direction indicated by the arrows, the locations of the Sanjiang Plain (highlighted in black area), the HLB and DG profiles (solid circles) mentioned in the text are shown.