Distinct similarities in the susceptibility records obtained from the three holes at Site 1098 provide tight constraints for a Site 1098 composite depth scale. Additional constraints come from lithologic features. Specific intervals from other data sets contain distinctive anomalies that correlate very well when placed into the preferred composite depth scale, confirming that the scale is accurate. Shipboard data collected from Site 1098 cores and placed into our mcd scale can be obtained from the ODP Janus database, which is available on the World Wide Web.
Coring in the two holes at Site 1099 provided only a few meters of overlap. None of the data sets within this limited overlap region provide convincing correlations. Thus, the preferred composite depth scale is the existing mbsf scale.
Composite scales, such as established here, represent first-order correlation between holes at a site upon which higher-order depth scales can be built. Smaller-scale features, such as individual lamina or sets of laminae, may not correlate exactly given the restriction that neither compression nor expansion of the length of individual cores was allowed in developing the mcd scales. For Site 1098, sets of laminae, as well as centimeter-scale variations in physical and magnetic properties, will likely be correlatable between holes and should naturally lead to fine-scale adjustments in the composite scale. Several other Leg 178 studies suggest such depth adjustments, most of which align features and data not considered in this study or which require compression or expansion of the mcd depth scale (Brachfeld et al., 2000; Pike et al., Chap 18, this volume; Nederbragt and Thurow, Chap 3, this volume). In some cases, these adjustments resulted in second-order improvements to the mcd depth scale, whereas in other cases they misaligned features that we consider robust. Through our illustrations, tables, and discussion of individual data sets, we hope to establish criteria that will guide future adjustments to depth scales for Sites 1098 and 1099 and to provide a stratigraphic framework for future investigators of the Palmer Deep to build upon.