Figures
Fig. 1 Distribution of bulk soil radiocarbon values with depth from a global compilation (3). Radiocarbon measurements represent a proxy for the average age of organic carbon in the soil (2). Midpoint depth of each horizon was binned into seven discrete depth intervals. Boxes enclose the 25th to 75th percentile of data, median is given as a vertical line within the box, and whiskers enclose the 10th and 90th percentile, whereas data points are individual values that fall outside of the whiskered interval. The number of samples in each interval is given on the right. Reference lines indicate the location of the Last Glacial Maximum (LGM; 22,000 years ago) and mid-Holocene period (6000 years) on the Δ14C scale, and any Δ14C value > 0 is considered modern (after 1955).
