Fig. 4

Residual version of the living trees composite chronology (gray) and the railroad ties superimposed on it (each one named with individual codes). Colors in the time series represent the start period of the first ring for each railroad tie series (dark green = from 1533 to 1700, brown = from 1701 to 1800, and orange = from 1801 to 1915). r = correlations coefficients, and t = t-value statistics for the common period of railroad series and the reference chronology.