Marine Sediments

Meteor

A bright tail or streak that appears in the sky when a meteroid is heated to incandescence by friction with Earth's atmosphere. It is often called a shooting star.

Stromatolite

A calcium carbonate sedimentary structure in which algal assemblages trap sediment and bind it into forms that are often dome shaped. They are known to form only in shallow-water environments.

Calcium carbonate

A chalk-like substance secreted by many organisms in the form of coverings or skeletal structures.

Limestone

A class of sedimentary rock composed of at least 50% calcium or magnesium carbonate. It may be either biogenous or hydrogenous.

Metal sulfide

A compound containing one or more metals and sulfur.

Phosphate

A compound containing the radical PO4. It is an important component of nutrients needed by algae for primary production.

Tektite

A cosmogenous globular mass composed of silicate rock material.

Spherule

A cosmogenous microscopic globular mass composed of silicate rock material (tektites) or of iron and nickel.

Core

A cylinder of sediment and/or rock material.

Diatomaceous earth

A deposit composed primarily of the tests of diatoms mixed with clay.

Oolite

A deposit formed of small spheres from 0.25 to 2 mm in diameter. They are usually composed of concentric layers of calcite.

JOIDES Resolution

A drill ship that replaced the Glomar Challenger in 1985. It has a tall metal drilling rig to conduct rotary drilling.

Aragonite

A form of CaCO3 that is less common and less stable than calcite. Pteropod shells are usually made of aragonite.

turbidity current

A gravity current resulting from a density increase brought about by increased water turbidity. Possibly initiated by some sudden force such as an earthquake, the turbid mass continues under the force of gravity down a submarine slope.

Chalk

A lithofied sedimentary deposit largely composed of coccoliths.

Wentworth Scale of Grain Size

A logarithmic scale for size classification of sediment particles.

Protozoan

A member of one-celled animals.

Rotary drilling

A method of drilling through rock that involves rotating a bit at the end of a "drilling string" of steel pipe.

Coccolithophore

A microscopic planktonic form of algae, encased by a covering composed of calcareous discs (coccoliths).

Integrated Ocean Drilling Program (IODP)

A new drilling program that replaced the Ocean Drilling Program in 2003 with a new drill ship that has riser technology, enabling cores to be collected from deeper within Earth's interior.

Siliceous ooze

A pelagic deposit that contains at least 30% biogenous siliceous particles.

Ooze

A pelagic sediment containing at least 30% skeletal remains of pelagic organisms, the balance being clay material. Oozes are further defined by the chemical composition of the organic remains (siliceous or calcareous) and by their characteristic organisms (diatom, foraminifer, radiolarian, or pteropod ooze).

Radiolarian

A planktonic, benthic protozoan that possess protective coverings usually made of silica.

Weathering

A process by which rocks are broken down by chemical and mechanical means.

Turbidite deposit

A sediment or rock formed from sediment deposited by turbidity currents and characterized by graded bedding.

Evaporite mineral

A sedimentary deposit that is left behind when water evaporates; includes gypsum, calcite, and halite.

Maturity

A texture of lithogenous sediment, where increasing maturity is indicated by decreased clay content, increased sorting, and increased rounding of the grains within a deposit.

Sorting

A texture of sediment where well-sorted sediment is characterized by having a narrow range of grain sizes.

Diatom

A type of algae that has a wall of overlapping silica valves.

Quartz

A very hard mineral composed of silica, SiO2.

K-T event

An extinction event marked by the disappearance of the dinosaurs that occurred about 65 million years ago at the boundary between the Cretaceous (K) and Tertiary (T) periods of geologic time.

Red Clay

Deep ocean deposits containing less than 30% biogenous sediment; usually red in color. AKA: Abyssal Clay.

Abyssal Clay

Deep ocean deposits containing less than 30% biogenous sediment; usually red in color. AKA: Red Clay.

Calcareous ooze

Deep sea sediment made of at least 30% calcareous biogenous particles like coccolithophores, foriminifers, globigerina, pteropod, and ostracod.

Glacial deposit

Deposit of rock fragments carried to the ocean by glaciers. The deposits form as the glacier ice melts and releases the rock fragments to the ocean floor.

Pelagic deposit

Deposits of sediment found on the deep ocean floor beyond the continental rise. They typically include abyssal clay, calcareous ooze, and siliceous ooze.

Ocean Drilling Program (ODP)

In 1983, this program replaced the Deep Sea Drilling Project to recover cores from the sea floor. It uses the drilling vessel JOIDES Resolution.

Manganese nodule

Lump containing oxides of iron, manganese, copper, or nickel found scattered in groups over the ocean floor.

Biogenous sediment

Material produced by plants or animals (ex. coral reefs, shell fragments, and tests of diatoms, radiolarians, foraminifers, and coccolithophores.

Terrigenous sediment

Mineral grains derived from the rock of continents and islands and transported to the ocean by wind or running water. AKA: lithogenous sediment.

Lithogenous sediment

Mineral grains derived from the rock of continents and islands and transported to the ocean by wind or running water. AKA: terrigenous sediment.

carbonate

Minerals that contain CO3 in its chemical formula.

Macroscopic biogenous sediment

Particles large enough to be seen without the aid of a microscope; includes shells, bones, and teeth of large organisms.

Sediment

Particles of organic or inorganic origin that accumulate in loose form.

Microscopic biogenous sediment

Particles that are so small they must be viewed with a microscope. They include tests of diatoms, radiolarians, coccolithophores, and foraminifers.

Nannoplankton

Plankton less than 50 microns (0.002 inch) in length that cannot be captured in a plankton net and must be removed from the water by centrifuge or special microfilters.

Foraminifer

Planktonic, benthic (bottom) protozoans whose protective covering is made of calcium carbonate.

Algae

Primarily aquatic, photosynthetic organisms that have no root system; can be micro or macroscopic.

Cosmogenous sediment

Sediment derived from outer space.

Hydrogenous sediment

Sediment that forms from ocean water precipitation or ion exchange between existing sediment and ocean water. Examples are manganese nodules, phosphorite, glauconite, metal sulfides, and various evaporite salts.

Silica

Silicon dioxide (SiO2).

Neritic deposit

That sediment composed of primarily lithogenous particles and deposited relatively rapidly on the continental shelf, slope, and rise.

Deep Sea Drilling Project

The 1st large-scale ocean drilling project that was conducted from 1963 - 1983. The drilling vessel used was the Glomar Challenger.

Grain size

The average size of grains in a sample of material.

Planktonic

The condition of an organism being carried about by ocean currents because of lack of sufficient means of locomotion to determine its position on the water column.

Calcite compensation depth

The depth at which the amount of calcite (CaCO3) produced by organisms in the overlaying water column is equal to the amount of calcite the water column can dissolve. There will be no calcite deposition below this depth, which, in most parts of the ocean, is at a depth of 4.5 kilometers (2.8 miles).

Lysocline

The depth in the ocean at which the carbon dioxide concentration is sufficient

Glomar Challenger

The drill ship specially designed for the Deep Sea Drilling Project.

Texture

The general physical appearance of an object (size/shape).

Calcite

The most common form of CaCO3.

Ice rafting

The movement of trapped sediment within or on top of ice by flotation.

Upwelling

The process by which deep, cold, nutrient-rich water is brought to the surface, usually by wind divergence of equatorial currents or coastal winds pushing water away from the coast.

Meteorite

The remains of a meteor that enters Earth's atmosphere and falls as a solid to the surface of Earth. They probably originate as fragments of asteroids.

Test

The supporting skeleton or shell (usually microscopic) of many invertebrates.

Coccolith

Tiny calcareous discs averaging 3 microns (0.0001 inch) in diameter that form the cell wall of coccolithophores.

Precipitate

To cause a solid substance to be separated from a solution, usually due to change in physical and/or chemical conditions.

Eroded

When material is worn away from Earth's surface by processes such as weathering, dissolution, abrasion, corrosion, and transportation.