In Figure , the Mary Rose core sample stands alone as very chemically degraded but unoxidized (compared to modern oak). All other samples show less chemical degradation paired with greater oxidation relative to modern oak. This suggests that the core Mary Rose sample has been protected from oxidative effects by its location within the beam, while chemical effects from bacterial degradation occurred, possibly to different degrees, in both locations. Further, as it is likely heartwood, it may well have started with a lower S/G ratio. The combination of these factors resulted in the very low value observed here. Within the other samples, considering only the guiacyl acid-to-aldehyde ratio, there is a further division: Mary Rose No PEG, Modern Oak and HMS Unicorn plot together, while HMS Victory, SB Tollesbury and Mary Rose Edge form a separate group. Except for SB Tollesbury, the members of this group are the samples which have benefited from conservation after centuries of wear. SB Tollesbury may simply be too young (i.e., without conservation) and as her hull ages, this value may shift towards that of the vessels which have not received treatment. This pattern is also somewhat preserved in the syringyl acid-toaldehyde data.