CATEGORY: ceramics DEFINITION: Perforating the wall of a ceramic artifact while still plastic by pushing a sharpened cylindrical tool (like an awl) through it or drilling a hole through a thin stone or fired ceramic.
CATEGORY: tool DEFINITION: A device for extracting columns of sediment from the ocean floor. Deeper cores are taken by the piston corer, which can take samples as long as 20 meters. In a piston corer, a closely fitted piston attached to the end of the lowering cable is installed inside the coring tube. When the coring tube is driven into the ocean floor, friction exerts a downward pull on the coresample. The hydrostatic pressure on the ocean bottom, however, exerts an upward pressure on the core that will work against a vacuum being created between the piston and the top of the core. The piston, in effect, provides a suction that overcomes the frictional forces acting between the sedimentsample and the inside of the coring tube. The hydraulic piston corer is used by deep-sea drilling ships and can take undisturbed cores of lengths up to 200 meters. Dates for the different layers are obtained by radiocarbon, paleomagnetism, or uranium series methods.
SYNONYMS OR RELATED TERMS: tazzae (pl.) CATEGORY: artifact DEFINITION: A cup-like vessel, usually in a light-colored fabric, with a stem and foot, decorated with bands of frilling. The frequent occurrence of signs of burning on the inner surface of such vessels indicates their possible use as lamps. May have been used in religious rituals.