Glossary definitions

An oil and gas well development process that typically involves injecting water, sand, and chemicals under high pressure into a bedrock formation via the well. This process is intended to create new fractures in the rock as well as increase the size, extent, and connectivity of existing fractures. Hydraulic fracturing is a well-stimulation technique used commonly in low-permeability rocks like tight sandstone, shale, and some coal beds to increase oil and/or gas flow to a well from petroleum-bearing rock formations.

A fissure on the floor of a sea out of which flows water that has been heated by underlying magma. The water can be as hot as 400°C (752°F) and usually contains dissolved minerals that precipitate out of it upon contact with the colder seawater, building a stack of minerals, or chimney. Hydrothermal vents form an ecosystem for microbes and animals, such as tube worms, giant clams, and blind shrimp, that can with stand the hostile environment. The hottest hydrothermal vents are called black smokers because they spew iron and sulfide which combine to form iron mono sulfide, a black compound.

Low dissolved oxygen levels in coastal and oceanic waters (<2mL per liter of water), either naturally occurring or as a result of a degradation (e.g. eutrophication).