Leg 68 of the Deep Sea Drilling Project used the newly developed Hydraulic Piston Corer (HPC) to recover two virtually continuous, undisturbed sections of late Neogene and Quaternary sediment. The sites are located in the western Caribbean (Site 502, 4 holes) and in the eastern equatorial Pacific (Site 503, 2 holes). The sediment of Site 502 is primarily foram-bearing nanno marl which accumulated at about 3 to 4 cm/thousand yr. The bottom of Site 502 (228.7 m) is ∼ 8 m.y. old. The sediment of Site 503 is primarily siliceous calcareous ooze which accumulated at about 2 to 3 cm/thousand yr. The bottom of Site 503 (235.0 m) is ∼ 8 m.y. old.
The magnetostratigraphy of both sites was determined on the R.V. Glomar Challenger with a long-core spinner magnetometer. All paleomagnetic boundaries through the Gilbert were identified in Site 502; most of them were identified in Site 503. The sediment at both sites shows a distinct cyclicity of calcium carbonate content. These relatively high accumulation rate, continuous, undisturbed HPC cores will enable a wide variety of high-resolution biostratigraphic, paleoclimatic, and paleoceanographic studies heretofore not feasible.