Climate Detective Glossary

biochemical sediments: form from the gradual accumulation of biologic material such as shells or dead plant material.
calving: the process by which an iceberg breaks off from an ice shelf or glacier.
chemical sediment: is composed of previously dissolved minerals that have either precipitated from evaporated water or been extracted from water by living organisms and deposited when the organisms died or discarded their shells.
climate: a region's long-term, average weather elements such as temperature and precipitation. The climate generally determines what kind of plants will grow in that region.
clastic sediments or rocks: are composed of fragments, or clasts of pre-existing minerals and rock. A clast s a fragment of geological detritus, chunks and smaller grains of rock broken off other rocks by physical weathering.
cryosphere: the set of all locations on or beneath Earth's surface where frozen water exists.
delta ¹⁸O record: a synonym for the ratio of ¹⁸O to ¹⁶O.
diatoms: microscopic unicellular marine or freshwater colonial alga having cell walls impregnated with silica.
dropstones: isolated fragments of rock found within finer-grained water-deposited sedimentary rocks. They range in size from small pebbles to boulders.
erosion: the wearing away of land surface by wind or water, intensified by land-clearing practices related to farming, residential or industrial development, road building, or logging.
forminifera (or forams): a type of zooplankton, a single-celled marine organism.
evaporite: is a sedimentary rock formed by evaporating sea water.
glacier: a mass of ice that originates on land, usually having an area larger than one tenth of a square kilometer; many believe that a glacier must show some type of movement; others believe that a glacier can show evidence of past or present movement.
half life: the time it takes for half the atoms in a radioactive substance to decay.
ice age: a cold period marked by episodes of extensive glaciation alternating with episodes of relative warmth.
iceberg: a piece of ice that has broken off from the end of a glacier that ends in water.
ice-rafted debris: when icebergs melt a certain amount of drifting, sediments of different sizes are deposited onto the bottom of the ocean. These pieces of sediment are normally larger than the surrounding fine-grained mud found there.
ice sheet: a dome-shaped mass of glacier ice that covers surrounding terrain and is greater than 50,000 square kilometers (12 million acres). e.g., the Greenland and Antarctic ice sheets
ice shelf: a portion of an ice sheet that spreads out over water.
index fossil: is a fossil of an organism known to have existed for a relatively short period of time, used to date the rock in which it is found.
interglacial period: is a geological interval of warmer global average temperature lasting thousands of years that separates consecutive glacial periods within an ice age.
isotope: one of two (or more) atoms of the same element which only differ in the number of neutrons found within its nucleus. e.g. H¹ (no neutrons) and H² (1 neutron), H³ (2 neutrons)
lithology: the mineralogy, grain size, texture, and other physical properties of granular soil, sediment, or rock.
magnetometer: a device used for measuring intensity of a magnetic field.
Milankovitch cycles: refer to long-term variations in the orbit of the Earth which result in changes in climate over periods hundred of thousands of years and are related to ice age cycles.
microfossil: a fossil that must be studied microscopically.
normal polarity: periods of time in the past in which the direction of the Earth's magnetic field was the same as the present direction.
paleomagnetism: the fixed orientation of a rock's crystals, based on the Earth's magnetic field at the time of the rock's formation, that remains constant even when the magnetic field changes over time.
paleontologist: a geologist who researches geological periods through the study of fossils.
phytoplankton: microscopic floating plants, mainly algae, that live suspended in bodies of water and that drift about because they cannot move by themselves or because they are too small or too weak to swim effectively against a current.
pollen: a fine powder produced by flowers that fertilizes other plants for reproduction.
principle of superposition: the scientific law stating that in any unaltered sequence of rock layers, each layer is younger than the one beneath it and older than the one above it, so that the youngest layer will be at the top of the sequence and the oldest at the bottom.
proxy data: is a past climate record like ice cores and tree rings used to interpret paleoclimate. Organisms, such as diatoms, forams, and coral serve as useful climate proxies.
radiolarians: protozoa with amoeba-like bodies and radiating filamentous pseudopods (latin for false feet).
reverse polarity: periods of time in the past in which the Earth's magnetic field was in the opposite direction from the present orientation.
sedimentation rate: the time it takes for a certain amount of sediment to be deposited on the sea floor (cm/year).
sedimentologist: a branch of geology that encompasses the study of modern sediments such as sand, mud (silt), and clay, and the processes that result in their deposition.
sediments: soil, sand, and minerals washed from land into water, usually after rain. Sediment can destroy fish-nesting areas, clog animal habitats, and cloud waters so that sunlight does not reach aquatic plants.
smear slides: a sample of sediment prepared by taking a small amount of it with a toothpick and mixing it with a few drops of distilled water before it is spread on a glass slide for observation.
strata: distinct horizontal layers in geological deposits. Each layer may differ from adjacent layers in terms of texture, grain size, chemical composition, or other geological criteria.
stratigraphy: a branch of geology which treats the formation, composition, sequence and correlation of the layered rocks as parts of the Earth's crust.
terrane: a group of rocks having a common age or origin.
thrust fault: a thrust fault is a type of fault, or break in the Earth's crust across which there has been relative movement, in which rocks of lower stratigraphic position are pushed up and over higher strata.
turbidity current: a current of rapidly moving, sediment-laden water moving down a slope through water, or another fluid. The current moves because it has a higher density than the fluid through which it flows—the driving force of a turbidity current derives from its sediment, which renders the turbid water denser than the clear water above.
weather: the state of the atmosphere at a given location and time. It includes such variables as temperature, precipitation, cloudiness, wind speed and direction, and relative humidity.
weathering: the process by which exposure to atmospheric agents, such as air or moisture, causes rocks and minerals to break down. This process takes place at or near the Earth's surface.
zooplankton: Small (often microscopic) free-floating aquatic plants or animals.