DSDP Site 585 was selected for drilling the Central Old Pacific as a relic of the Mesozoic superocean Panthalassa. The basal lithologic unit recovered from Holes 585 and 585A is composed of a thick section of Aptian-Albian volcaniclastic turbidite deposits containing carbonate debris.On the basis of both microstructure and genesis, the carbonate debris consists of various shallow-water skeletal fragments, as well as at least two types of ooids. The most distinct change in the shallow-water skeletal debris observed within the unit is the type of large, benthic foraminifers. In the lower Aptian portion of the unit, forms having an affinity to Orbitolina texana (Roemer) are observed. In the upper Albian portion of the unit, these are replaced by large, benthic foraminifers of a complex, agglutinated type from the family Ataxophragmiidae.Microstructurally, the ooids have concentric laminations of micrite or radial needles. The radial needles are usually truncated by the next concentric layer. Fossil content indicates that the micritic ooids formed in two different environments. Some specimens contain shell fragments and miliolids, which provided nuclei for the formation of typical shallow-water ooids. Some ooids contain planktonic foraminifers. These planktonic foraminifers could have been washed into shallow-water environments during storms and subsequently incorporated into the development of ooids, but their presence may indicate development in a pelagic environment.