Composite Depth Scales from Ocean Drilling
Composite depth scales are constructed to correlate coeval features between multiple drill holes at a common drill site. A couple composite depth scales I have constructed are published in:

McGuire, J.C., and Acton, G.D., Composite depth scales for the Japan Trench, ODP Leg 186 Sites 1150 and 1151, Proc. ODP, Sci. Results, 186. Published online February 2003. [download pdf reprint] http://www-odp.tamu.edu/publications/186_SR/102/102.htm

Acton, G.D., Borton, C.J., and the Leg 178 Science Party, Palmer Deep composite depth scales for Leg 178 Sites 1098 and 1099, In Barker, P., Camerlenghi, A., Acton, G.D., and Ramsay, A.T.S. (Eds.), Proc. ODP, Sci. Results, 178 Published online June 2001. [download pdf reprint]. Also available at:
http://www-odp.tamu.edu/publications/178_SR/chap_05/chap_05.htm

Background For Ocean Drilling Program cores, the depth to the top of each core is originally estimated from a drill-pipe measurement. These drill-pipe measurements, along with curation procedures, establish a unique depth scale in meters below seafloor (mbsf) for the cores from each hole. The mbsf depths differ from true depths for several reasons such as ship motion, tides, heave, deviation of the drill hole from vertical, and core expansion. Given these factors, one would expect misalignment of correlative features between holes at a site. Thus, a continuous horizontal feature collected in several holes at a site, which in the absence of local bathymetric variations would have the same true depth in each hole, will likely have different mbsf depths. The offset of such features in the mbsf depth scale may be only several centimeters or could be a few meters, though rarely more than 10 m, based on observations from past Deep Sea Drilling Project (DSDP) and ODP legs

A composite depth scale seeks to overcome many of the inadequacies of the mbsf depth scale, allowing core data from one hole to be compared or combined ("spliced") directly with core data from other holes at the same site. The construction of composite depth scales is a natural outcome of efforts to obtain complete recovery of sedimentary sections by piston coring two or more offset holes at a site, which began with the use of the hydraulic piston corer during DSDP Leg 68 (Prell, Gardner, et al., 1982) and has become standard practice since APC coring began during DSDP Leg 94 (p. 8-9 of Ruddiman, Kidd, Thomas, et al., 1987; see also Hagelberg et al., 1995, for a history of composite section development). Cores from a single hole will nearly always have some intervals with poor or no recovery or with recovery of sediments that are disturbed during drilling. Even when core recovery is quoted as 100% or higher, gaps of several meters can occur between cores. By splicing or stacking core intervals from different holes at a site that has been multiply cored, a complete or nearly complete stratigraphic section can be constructed.