A single hole of 362.7 mbsf was rotary drilled at Site 1103 to obtain glaciomarine and preglacial sediments. The upper part of Hole 1103A (0-247.3 mbsf) and all of Hole 1100D (0-100.9 mbsf) contain intervals of poor recovery: 2.3% and 4.8%, respectively. Recovery at Site 1102 consisted of coarse clasts of hard rock, originally from diamicts or dropstones, with the exception of one small sample of sediment from Hole 1102C. This sediment became a single small paleontological sample (Sample 178-1102C-2R-CC) that was examined only for foraminifers. It was found to contain rare planktonic foraminifers (Neogloboquadrina pachyderma sinistral) and was barren of benthic foraminifers. Samples 178-1100D-1R-CC through 12R-CC (0.05-100.9 mbsf) and Samples 178-1103A-1R-CC through 24R-CC (0.2-218.4 mbsf) contain isolated large clasts with small amounts of fine sediment on or between them. Microfossils (radiolarians, diatoms, and foraminifers) are rare to barren in these sediments, and those that are present could be reworked. The presence of late Pliocene and Pleistocene diatoms suggests that the sediments in Hole 1100D and the upper part of Hole 1103A were deposited during or after this time. The lower part of Hole 1103A, between 247 mbsf and the bottom of the hole (Cores 178-1103A-27R [247.3 mbsf] through 38R [362.7 mbsf]), had better core recovery (3% to 67%). It contains marine diamictite, mudstone, and sandstones (see "Lithostratigraphy"). The three fossil groups examined were very rare in abundance and provide poor age assignments (pre-Pliocene, possibly late Miocene, based on diatoms).
All core-catcher materials from Hole 1100D were examined. However, only poorly preserved, fragmented, rare diatoms were observed from the upper part of this hole. The appearance of Fragilariopsis kerguelensis in Samples 178-1100D-1R-CC through 3R-CC suggests that those sediments are younger than the first occurrence age of this species (3.3 Ma). Samples 178-1100D-4R-CC through 12R-CC were barren or contained only unidentifiable diatom fragments.
At Site 1103, smear slides of all core-catcher samples, and additional samples taken within the split sections of the core, were examined for diatoms. Diatoms were mostly rare at Site 1103. Valves were often fragmented beyond the limit for identification, yet these fragments can be abundant in the material recovered.
Samples 178-1103A-1R-CC through 6R-CC (55.2 mbsf) contain only rare fragments of F. kerguelensis (present to 3.3 Ma) (Fig. F12). The absence of Pliocene to early Pleistocene diatoms, which appear in the middle part of this hole, suggests an age younger than early Pleistocene.
The middle part of this hole, Samples 178-1103A-11R-CC (93.7 mbsf) through 24R-CC (228 mbsf), contains low numbers of several biostratigraphic index species. Co-occurrence of Actinocyclus ingens, Fragilariopsis barronii, Thalassiosira insigna, Thalassiosira inura, Thalassiosira oestrupii, and Thalassiosira torokina suggests that these samples are younger than the first appearances of these species and may be placed into the Thalassiosira kolbei Zone or the lower part of the A. ingens Zone (Fig. F12). The absence of Thalassiosira vulnifica supports this age assignment. The lower portion of Hole 1103A from Samples 178-1103A-31R-1, 22 cm (286 mbsf), to the bottom of the hole at Sample 178-1103A-38R-CC (355.34 mbsf) has a lower abundance of diatoms and no Pleistocene to Pliocene species. The occurrence of Denticulopsis simonsenii s.l. suggests that this interval is younger than the first occurrence of this species (14.18 Ma). A trace occurrence of Nitzschia januaria and Rouxia californica in Sample 178-1103A-31R-1, 63 cm (286.4 mbsf), may allow this sample to be placed in the late Miocene (Fig. F12). The better preservation of D. simonsenii s.l. may indicate a close source area, if the specimens are reworked, or an environment with high sedimentation rate (see "Lithostratigraphy"). Light yellowish gray pebble-sized clasts of soft sediment within the diamict in Core 178-1103A-34R contain a nearly monospecific diatom assemblage dominated by Stephanopyxis grunowii and Thalassionema/Thalassiothrix fragments. Another clast from the same core has a different diatom assemblage, dominated by Denticulopsis spp. but still having a high diversity, including other species (Thalassiothrix/Thalassionema spp. and Fragilariopsis/Nitzschia spp.). The existence of these well-preserved clasts within the diamictite matrix and the lack of abundant diatom species in the matrix add support for a close source location for the clasts.
Trace amounts of radiolarians were observed at Site 1100. Most of the skeletons were reworked or recrystallized. No age-diagnostic in situ specimens were found.
Radiolarians are sparse with poor to moderate preservation in core-catcher samples from Site 1103, making biostratigraphic determinations nearly impossible (Fig. F12). Radiolarians are present in Samples 178-1103A-1R-CC (10.8 mbsf), 6R-CC (55.2 mbsf), 13R-CC (122.6 mbsf), 23R-CC (218.4 mbsf), and 24R-CC (228.0 mbsf). Reworked Cretaceous radiolarians were present in all but Sample 178-1103A-1R-CC. Sample 178-1103A-24R-CC (228.0 mbsf) contained an assemblage indicative of the Upsilon Zone, but considering the age based on diatoms, this is probably reworked. Marker species were not encountered in any other samples.
Foraminifers are absent to rare in core-catcher samples from Sites 1100 and 1103. In Samples 178-1103A-1R-CC through 24R-CC (0.2-218.4 mbsf) and Samples 178-1100D-1R-CC through 12R-CC (0.05-100.9 mbsf), the fauna contains rare, well-preserved, and white Neogloboquadrina pachyderma sinistral along with older, reworked, darker colored benthics and planktonics. In addition, Inoceramus prisms, sponge spicules, and recrystallized radiolarians are found. In Samples 178-1103A-27R-CC through 35R-CC (250.58-326.49 mbsf), the foraminiferal fauna was rare, with more evidence of reworking. Samples 178-1103A-31R-CC and 33R-CC contain the most abundant assemblages, with well-preserved specimens of Cassidulinoides parkerianus along with a substantial reworked component. The lowest three samples, 178-1103A-35R-CC through 38R-CC (338.77-355.34 mbsf), are barren of foraminifers.