Chapter 6: Ocean Sediments

ooze

(of a thick liquid) pass or flow slowly; N: mud or thick liquid as at the bottom of a river

Diatoms

A unicellular photosynthetic algae with a unique glassy cell wall containing silica

mollusk

An invertebrate with a soft, unsegmented body; most are protected by a hard outer shell.

grain size

the size of the grains that make up a rock, which helps to classify the type of rock

Runoff

water that flows over the ground surface rather than soaking into the ground

turbulence

wild or disturbing activity

weathered

worn by long exposure to the air; weather-beaten.

wetland

A land area that is covered with a shallow layer of water during some or all of the year

Delta

A landform made of sediment that is deposited where a river flows into an ocean or lake

glacier

A large mass of moving ice and snow on land

Fjord

A long narrow inlet from the sea between steep cliffs or hills

graded beds

A sediment layer characterized by a decrease in sediment size from bottom to top.

Fossil

A trace of an ancient organism that has been preserved in rock.

slump

A type of mass movement that occurs when a mass of material moves down a curved slope

Adsorption

Assimilation of gas, vapor, or dissolved matter by the surface of a solid or liquid.

detritus

Dead organic matter

Pelagic

Describing organisms that live in the water column away from the ocean bottom.

Radiolaria

Heterotrophic single-celled protists with a porous shell of silica and long cytoplasmic extensions.

colloidal

pertaining to a gluelike substance

Foraminifera

Marine protozoans that have variably shaped shells with small holes.

Phytoplankton

Microscopic, free-floating, autotrophic organisms that function as producers in aquatic ecosystems

Diffusion

Movement of molecules from an area of higher concentration to an area of lower concentration.

relict sediments

On continental shelf; do not change with the environment

decomposers

Organisms that break down the dead remains of other organisms

Frustule

the shell of a phytoplankton that is made up of silicon (glass)

Deposition

Process in which sediment is laid down in new locations.

Erosion

Processes by which rock, sand, and soil are broken down and carried away (i.e. weathering, glaciation)

fecal pellets

Sand-sized grains found in carbonate mud that have passed through the guts of invertebrate organisms.

contiental shelf

Sandy, gently sloping underwater plain boarding the coast of a continent is?

terrigenous sediment

Sediment derived from the land and transported to the ocean by wind and flowing water.

Biogenous

Sediment that is made up of the skeletons and shells of marine organisms.

residence time

The average time a given particle will stay in a given system

Carbonate Compensation Depth (CCD)

The depth in the ocean below which material composed of calcium carbonate is dissolved and does not accumulate on the seafloor.

electrostatic

The force between electrically charged objects.

Zooplankton

Tiny floating organisms that are either small animals or protozoa.

pore water

Water that is left in the clay even though it may appear completely dry.

lagoon

a body of water cut off from a larger body by a reef of sand or coral

Diagenesis

a collective term for all the chemical, physical, and biological changes that take place after sediments are deposited and during and after lithification

sorted sediments

a deposit of sediments that are similar in size (or shape, or density); the greater the similarity of particles the more sorted the sediments

turbidity current

a downslope movement of dense, sediment-laden water created when sand and mud on the continental shelf and slope are dislodged and thrown into suspension

abyssal plain

a large, flat, almost level area of the deep-ocean basin

submarine canyon

a seaward extension of a valley that was cut on the continental shelf during a time when sea level was lower, or a canyon carved into the outer continental shelf, slope, and rise by turbidity currents

limestone

a sedimentary rock consisting mainly of calcium that was deposited by the remains of marine animals

Coastal Plain

area of flat land along a sea or ocean

siliceous ooze

biogenous sediment composed of the silica based shells of single-celled animals and algae

Cosmogenous

derived from outer space

Turbidites

graded layers of terrigeneous sand interbedded with finer pelagic sediments of the deep sea floor

shore

land bordering the sea, a lake, or a large river

calcareous

made of calcium carbonate

Coccolithophores

microscopic algae with calcium carbonate shells, form the base of many marine food webs

hard parts

parts of organisms most likely to become fossils

biochemical cycle

process in which elements, chemical compounds and other forms of matter are passed from one organism to another

marginal sea

relatively large semi-isolated body of water

Leaching

removal of dissolved materials from soil by water moving downwards

Hydrogenous

seafloor sediment consisting of minerals that crystallize from seawater

lithogenous

sediment made of rocks eroded from the continents by water wind waves

Evaporites

sedimentary rocks formed from minerals left after water evaporates

excreted

separate and expel as waste

Pteropods

small, graceful, swimming snails

hydrothermal vents

spots on the ocean floor where hot gases and minerals escape from earth's interior into the water

cohesive

sticking or holding together; unified

Bioturbation

the disturbance of sedimentary deposits by living organisms