Temperature: ¡F = (9/5)* ¡C + 32 F:  Fahrenheit C:  Centigrate Distance: 1 mile = 1.6 km km:  Kilometer		Download text of this section - 5K
Archaea	Bacteria (single-celled organisms) that live at high temperatures such as the high temperatures found within hydrothermal vent structures.
autotroph	An organism that can get energy directly from sunlight through the process of photosynthesis.
bathymetry	Depth from the sea surface to the seafloor.
black smoker	A chimneylike structure made up of sulfur-bearing minerals that actively bellow black smoke.
buoyancy	The tendency for less-dense material to rise.
chemosynthesis	The process of using chemical energy to create food.
chemotroph	An organism that gets energy from the oxidation of chemicals. At deep-sea hydrothermal vents, the chemotrophs oxidize hydrogen sulfide in the water that discharges from black smokers.
clay mineral	A hydrous mineral formed by interaction between a hydrothermal solution and a mineral such as feldspar, mica, pyroxene, etc.
collapsed lava pits	Features created when the tops of lava tubes collapse inward.
core	The spherical mass, consisting largely of metallic iron, at the center of Earth. The radius of the core is approximately 3,000 kilometers.
crust	The outermost and thinnest of Earth's compositional layers, the crust consists of rocky material that is less dense than the rocks of the mantle below. The continents make up the continental crust, and the crust beneath the oceans is the oceanic crust. The oceanic crust varies in thickness from 6 to 8 kilometers, and the continental crust varies in thickness from 30 to 70 kilometers.
crystalline rock	Rock consisting of minerals in an obviously crystalline state. Often used to refer to slowly cooled igneous rocks.
crystallization	The process through which minerals grow from a liquid.
dikes	Thin, tabular, parallel-sided sheets of intrusive igneous rocks that generally cut across existing rock layers in a roughly vertical fashion.
earthquake	A sudden motion or tembling in the earth caused by the rapid breaking of rocks along faults.
ecosystem	A group of organisms and their habitat.
fault	A fracture in a rock along which movement occurs or has occurred.
fissures	Open cracks such as those that form in the oceanic crust due to plate separation.
fracture zones	Valleys on the ocean floor that run perpendicular to ocean ridges, separating offset segments of the ridge. Fracture zones are bound by both strike-slip faults and normal faults. Rocks from the deep oceanic crust are often exposed by these faults.
hydrothermal	An adjective applied to heated or hot-water-rich solutions.
hydrous	An adjective applied to water-bearing substances.
igneous mineral	A mineral that forms when magma or lava solidifies.
lava	Molten rock that erupts onto Earth's surface.
lystric fault	A fault with a curved fault surface. Many of the normal faults along the ocean ridges are lystric. They penetrate down into the crystalline rock of the oceanic crust.
magma	Molten rock under Earth's surface.
mantle	The thick shell of dense, rocky material that surrounds the core and lies beneath Earth's crust. The mantle is approximately 2,800 kilometers thick.
mid-ocean ridge	A 50,000 km submarine mountain range along which oceanic plates are formed.
mineral	Any naturally formed crystalline solid with a definite chemical composition and a characteristic crystal structure.
ocean basin	The ocean floor that includes the submerged plains and ocean ridges.
oceanic crust	The crust beneath the oceans.
ore	An aggregate of minerals from which one or more minerals can be extracted for profit.
photosynthesis	The process of using sunlight to create food.
pillow lavas	Rounded pieces of basaltic lava that are created when the lava erupts under water.
plates	The rigid pieces that make up the puzzle of Earth's crust.
precipitation	The separation of minerals from a liquid or gas.
reactivity	The tendency for one substance to dissovle another substance.
ROV	Remotely operated vehicle, in this case a remotely operated submersible.
sessile	The tendencey to stay in one place.
sheet flows	Thin, flat flows similar to those that are found on Hawaii.
solution	A liquid combination of a liquid and a nonliquid substance.
spreading	The separation of plates such as the spreading that occurs along midocean ridges.
subduction	Plunging of oceanic plates along trenches either within the oceans or along their boundary with the continents.
submersible	Research vessel designed to dive beneath the ocean surface. Deep-sea submersibles are designed to go to depths greater than ordinary submarines (depths greater than 2,000 meters).
sulfates	Oxygen-rich sulfur-bearing minerals.
sulfide mounds	Large piles of sulfide minerals built up over time.
sulfides	Oxygen-poor sulfur-bearing minerals.
symbionts	Usually refers to at least two organisms that need each other to survive, with one organism living within the other organism.
tectonic	A term designating rock structures and external forms resulting from the deformation of Earth's crust.
thermophyllic	Heat loving.
topography	Variation in altitude of the landscape.
zero-age	Oceanic crust formed with the last 10,000 years.