Sediments become semilithified by 100-110 mbsf. We observed very rare tephra layers and disseminated volcanic ash, locally concentrated in burrows. Within this depth interval, three volcanic ash layers have high P -wave velocities. The base of the pelagic section is earliest Oligocene in age. Index properties change significantly near the boundary between Units III and IV, from 381.4 to 384.4 mbsf.
Grains are predominantly highly altered volcanic lithic fragments.
Bryozoans, bivalves, and echinoids are the major biogenic components. Well-rounded cobbles at the top of the basement suggest a beach deposit at the base of the sedimentary succession. All basement units are highly altered and fractured. The high degree of alteration and poor core recovery in Units 1-5 make it difficult to identify physical volcanic features and interpret modes of emplacement. However, these units can be distinguished in the natural gamma ray logs.