Trees, especially ancient baldcypress, hold many clues to the past. After baldcypress cores are corrected statistically to adjust for missing or extra rings using a process called cross dating, they may be correlated to water levels, temperature, sedimentation, erosion, and other environmental events. This is often useful in re-establishing ancient ordinary high water marks and boundaries on natural lakes. Willis Engineering and Scientific has a dendchronology/dendrohydrology laboratory set up to cross date trees an correlate their ring spacings with environmental conditions.