Abduction

GLOSSARY

Asthenosphere A zone within the earth ranging in depth from 50 to 200 km; it is the upper part of the mantle (see below), situated directly below the lithosphere (see below). This area is theorized to be molten and yielding to plastic flow.

Basalt A dark, almost black rock formed from the cooling and solidification of molten silicate minerals. It forms a large part of the oceanic crust.

Bathypelagic An adjective relating to moderately deep ocean depths (2,000- 12,000 ft).

Caldera A crater formed by the collapse of a volcano’s summit.

Circadian An adjective relating to a twenty-four-hour cycle.

Dike A tabular rock formation arising from molten rock forced up a cleft or fissure and then solidifying.

Dinoflagellates A type of plankton (see below) that includes many bioluminescent varieties. Dinoflagellates also cause red tide.

Ectogenesis Embryonic development outside the womb.

Epipelagic An adjective relating to the part of the surface ocean in which enough light penetrates to support photosynthesis.

Foraminifera Tiny marine protozoans whose calcerous shells form chalk and the most widely distributed limestone.

Gabbro A dark, sometimes green rock that makes up a significant part of the lowest part of the oceanic crust.

Gamete A male or female germ cell.

globigerina ooze A cream-colored muck that covers a good portion of the deep ocean floor and is composed mainly of the minute skeletons of foraminifera (see above).

Graben A fault block that has dropped below the height of the surrounding rock.

Guyot A seamount (see below) with a flat top.

Lithosphere The rigid crust of the earth; it includes the sea floor as well as the continents.

Mantle An inner layer of the earth, between the lithosphere (see above) and the central core.

Microsome Any of the various minute subcellular structures.

Mohorovicic discontinuity An area within the earth where there is a large change in the transmission of seismic waves. It is between 5 and 10 km below the ocean floor and about 35 km below the continents.

Pangaea A single continent that began breaking up in the Mesozoic era by the action of plate tectonics to form the present-day continents.

Peridotite A dark rock deep within the mantle.

Plankton Microscopic plants (phytoplankton) and animals (zooplankton) that exist in such prodigious numbers that they form the base of the oceanic food chain.

Richter scale A method of expressing the magnitude of earthquakes.

Seamount An underwater mountain usually formed by volcanic activity.

Thermocline A relatively stable, abrupt temperature change in a body of water.

Zygote A cell formed by the union of two gametes (see above) which has the potential to form a new individual.