Figure 5

Box plots by age for ACL and CPI. (a) Average chain length of the C₂₁-C₃₃ n-alkanes (ACL_21-33). (b) Carbon preference index of the C₂₁-C₃₃ n-alkanes (CPI_21-33). The thick black lines show the mean values from each period, while the widths of the boxes are proportional to the square-roots of the number of observations.