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Glossary Advection Usually horizons Art of air or water, as a current. Anticline A fold or arch of stratified rock whose layers bend downward from the crest and whose core contains strati graphically older rocks. Baroclinicity A condition in which surfaces of equal pressure are in clined to surfaces of equal density. Ben~os The organisms that live in or on Be bottom of water bodies. Hence Antic. Brookian A local term indicating geological age applied to nor ~ern Alaska. Cambrian The earliest period of the Paleozoic era, thought to have covered Be span of time between 570 and 500 million years ago. Made up of fragments of pre-ex~sting rocks. Coriolis force Apparent force due to Earths rotation Hat deflects mo ving objects to He right in the northern hemisphere and to He left in He southern hemisphere. The magnitude of force increases as one moves toward He poles. 243

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244 OCS DECISIONS: ALASKA Cretaceous The final period of Me Mesozoic era (after He Jurassic and before the Tertiary period of He Cenozoic era), drought to have covered He time span between 135 and 65 million years ago. Cryology The study of snow and ice. Danian The lowest (oldest) division of He Tertiary period. Deformation A general term for He processes of folding, faulting, shearing, compression, or extension of a material such as a rock or sea ice. Devonian A period of He Paleozoic era (after He Silurian and before He Mississippian), Nought to have covered He span of time between 400 and 345 million years ago. Eocene An epoch of He early Tertiary period, after He Pale ocene and before He Oligocene. Foredeep A deep depression in He ocean bottom fronting a mountainous land area. Frazi! ice Ice chisels or granules sometimes resembling slush that are formed in supercooled turbulent water. When these ice crystals float to He surface, Hey form a layer of fine-grained, granular ice. Geostrophic Resulting from a balance between He pressure gradient force and He Coriolis force (as in He geostrophic windy. Graben A depressed segment of He Earn' s crust bounded on at least two sides by faults and generally of greater length Han width. Halocline A location in He water column where there is a usually sharp vertical gradient in salinity.

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GLOSSARY 245 Hydrography The science of describing the waters of the Earth's surface comprising the study and mapping of their forms and physical features; i.e., the contours of the sea bottom, shallows, winds, tides, and currents. Lead A long narrow open water opening passing through a region of sea ice navigable by surface vessels and air breathing mammals. It is often said that the difference between a crack and a lead is that one can row a boat down a lead. Littoral Of, relating to, on, or near a shore, especially of the sea. Maestrichtian Marine boundary layer Miocene Oligocene Of, pertaining to, or designating the uppermost division of the Upper Cretaceous in Europe. It immediately underlies the Danian stage. The region of the atmosphere over He sea where heat, moisture, and momentum are exchanged by turbulent transfer between the sea surface and the air. The layer' s depth varies, typicalRy from a few hundred to a thousand meters. An epoch of the Tertiary period, after the Oligocene and before the Pliocene. An epoch of the Tertiary period after He Eocene and before He Miocene. Orographic Of or relating to mountains, especially wig respect to dleir location, distribution, and accompanying phenom ena (e.g., orographic lifting of air). Pelagic Of, relating to, or living in the open sea or in midwater; not associated with the benthos. Pleistocene An epoch of the Quaternary period, after He Pliocene of He Tertiary and before He Holocene.

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246 OCS DECISIONS: ALASKA Pliocene An epoch of tile Tertiary period, after the Miocene and before He Pleistocene Polynya A large area of open water or atypically thin ice in a location Rat is surrounded by sea ice and where climatologically sea ice should occur. The term is commonly applied to a persistent feature. Reservoir rock A subsurface volume of porous and permeable rock in which of! or gas has accumulated. Rift A long, narrow continental trough bounded by normal faults. Silurian A period of Be Paleozoic era, thought to have covered We span of time between 440 and 400 million years ago. Slump The sliding down of a mass of sediment shordy after its deposition on an underwater slope, especially He downsiope flow of soft unconsolidated marine sediments at He head or along He side of a submarine canyon. Source rock The geological formation in which oil and gas originate. Stradgraphic A chronological succession of sedimentary rocks from sequence older below to younger above, essentially without inter ruption. Subsea Completion of an of! well win the wellhead at the sea completion floor. Synthetic A technique in which numerical procedures are used to Aperture generate high-resolution radar images. For the proce Radar cure to work, the radar move at a known rate (e.g., on an airplane or satellite) over He terrain to be imaged. Taxon A group of organisms classified according to presumed (pi. taxa) evolutionary relationship. Examples of taxa include phy lum, family, genus, species.

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GLOSSARY 247 Tectonic Of or relating to deformation of Me Earths crust, We forces involved in or producing such deformation, and He resuldng rock structures and external forms. Tertiary The first period of Be Cenozoic era, Fought to have covered the span of dine between 65 and 2 million years ago. Transgression The spread of the sea over land areas; any change that brings offshore, deep-water environments to areas occupied by nearshore, shallow-water conditions, or that shifts He boundary between marine and nonmarine de position outward from He center of a marine basin.

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