Glossary of some advanced and specialised terms encountered during, and relevant to, a study of East Yorkshire coastal erosion.
aliquot
Portion of a larger whole, especially when a sample taken for analysis.
allochthonous
Denoting a deposit or formation that originated at a distance from its present position.
anisotropic
Having a different physical property or varying in magnitude according to direction of measurement. Opposite is isotropic.
anostomosis
Cross-connection between adjacent channels or streams. Also rejoining of previoulsy separated streams.
anticline
Trough or fold of stratified material in which the strata slope downwards from the axis (i.e. an upwardly convex structure). Opposite is syncline.
aquiclude
Geological formation that may absorb and hold water but does not allow it to pass through. See also aquitard.
aquifer
Underground layer of very porous water-bearing material, e.g. soil, sand, gravel. Heavily fractured beds of sedimentary rock such as chalk, limestone, and sandstone are also aquifers.
aquitard
A bed of low permeability, i.e. a ‘retarding’ layer, that acts as a limiting barrier for groundwater. See also aquiclude.
arenaceous
Consisting of sand or particles of similar grain size.
argillaceous, argillic
Of or relating to clay or clay materials.
bathymetry
The study of the topography (contours and relief) of the seabed. Also in reference to a local situation, e.g. the bathymetry of the near shore at [location].
boreal
Relating to, or located in, northern regions.
clast
Piece or fragment of rock, such as found in glacial till.
consolidated / unconsolidated
Some ambiguity exists as to whether the glacial tills of the East Riding of Yorkshire should be described as consolidated or unconsolidated.
Generally, a geological deposit may be regarded as consolidated when compacted by overburden, such as another deposit above. It can be called overconsolidated if compacted under an overburden pressure greater than existing at the present time (that is, the load was removed at some time in the past).
However, the tills of East Yorkshire are composed of sediment particles laid down in a loose and essentially unsorted arrangement. They are geologically soft and easily succumb to processes of erosion. Although there was at one time the overburden of glacial ice, for the purposes of practical study the tills are deemed to be unconsolidated.
comminution
Gradual reduction of material to minute particles or fragments.
cryoturbation
Churning and mixing of soils caused by freezing and thawing.
DEM (Digital Elevated Model)
A 3D computer graphics representation of elevation data to represent terrain.
depo-centre
The location of the deepest deposit in a sedimentary basin.
depth of closure (DoC)
The depth away from the shore beyond which no significant sediment transport takes place. Seaward boundary of the littoral zone.
diagenesis
The process of alteration of a sediment which takes place after its deposition.
diamict
Very poorly sorted sediment, typically gravel size grains in a matrix of fine sand. Once glacial origin has been established, the deposit can be called a till.
diapir
Domed formation piercing an overlying stratum or strata.
drape
Appearance of a fold but might form simply through sagging or differential compaction of layers around a pre-exisiting structure.
fabric
Spatial and geometric configuration of all the elements that make up a deposit. In glacial till, the fabric can provide information on directions at the time of deposition.
facies
See LFA (lithofacies association).
flocculation
Process by which small particles suspended in water bind together to form larger particles or lumps.
imbrication
An overlapping of edges, like roofing tiles.
indurate
To harden, as a sedimentary deposit might under the weight of overlying material.
intercalated
Inserted between layers.
isoclinal
Denoting a fold in which the two limbs are parallel.
isotropic
Having the same physical property or magnitude according to direction of measurement. Opposite is anisotropic.
lattisepic
See fabric.
LFA
A facies is a depositional entity distinct from adjacent deposits. Facies are often presented as an LFA, or lithofacies association, in order to depict a representational sequence of different environments.
Individual facies within an LFA are indicated and described using a coding scheme.
LFA codes (PDF)LR04
The LR refers to Lorraine E. Lisiecki and Maureen E. Raymo, and 04 is 2004, the year leading up to the publication of their benthic stack. See also MIS.
macrofabric
Preferred orientation of clast long axes. See fabric.
matrix
Finer grained mass of material, e.g. glacial till, in which larger grains or clasts are embedded.
MIS (Marine Isotope Stage)
The ratio of two isotopes of oxygen present in oceans alters according to climate. Oxygen-16 is the lighter, and evaporates more easily than Oxygen-18. During periods of climatic cooling, evaporated water falls as snow and oxygen-16 is locked up in ice.
Oxygen-18 becomes more concentrated in the seas, and in the calcite shells of tiny organisms (foraminifera) that live there. When the organisms die, their shells sink to the floor of the ocean to form accumulations in the sediment.
By taking cores from ocean floor sediment, it is possible to measure changes in the isotopic ratio within shell material and therefore to estimate past global temperatures. Each major change is recorded as a marine isotope stage, working backward from the present, MIS 1. Odd numbers in the MIS scheme represent warm periods, even numbers cold (e.g. glacial).
See also LR04.
neritic (zone)
Region of shallow water overlying a continental shelf. Also sublittoral.
omniseptic
See fabric.
OSL (Optically Stimulated Luminescence)
Optically stimulated luminescence (OSL) is a technique used in dating late Quaternary deposits.
As sediment is transported by wind, water, or ice, it is exposed to sunlight. Once this sediment is deposited and subsequently buried, it is removed from light and subjected to low levels of surrounding natural radiation.
Over a period of time, electrons freed by ionisation become trapped in defects or holes within the crystal lattice of grains of quartz and feldspar, and some other minerals. By measuring the percentage of accumulated electrons through various processes in the laboratory, estimates of age may be made.
paleopedology
Study of buried and relict soils.
palynology
Study of the geographic distribution and seasonal production of pollen.
pedogenic
Relating to formation and development of soil.
pedostratigraphy
Study of soils.
pseudomorph
Replacement or substitution of something by something else, with appearance and dimensions remaining the same. Usually applied to mineral replacement (an example is the formation of a fossil).
In the context of the present study, a crack in the ground surface caused by ice during glaciation later fills with sediment and is today seen in the cliff face as an ice wedge pseudomorph.
radiocarbon dating
The carbon that plants and animals absorb from the atmosphere throughout their lifetimes includes a weakly radioactive isotope – carbon-14, or 14C. When the organism dies, the 14C content starts to decay at a fixed rate, and the changed ratio with other carbon isotopes allows for estimation of years since death.
Variations in past atmospheric concentrations mean that radiocarbon and calendar ages are not identical. Conversion is carried using a calibration curve.
radfiocarbon to calendar date conversionrheology
Science of physical deformation and flow of matter.
riedal
Refers to small right-lateral faults gently inclined to the strike of the main fault.
skelseptic
See fabric.
syncline
Trough or fold of stratified material in which the strata slope upwards from the axis (i.e. an upwardly concave structure). Opposite is anticline.
terminus ante quem
The latest possible date for an event.
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Prepared and maintained by Brian Williams.
