Glossary of terms used within thin section micromorphology of glacigenic sediments
Please note that this informal glossary is unpublished, and based on terms used extensively within the papers cited in the reference list. In all cases, you should not use this glossary as a formal reference, and should explore the published literature for more detail on specific terms and terminology.

  • birefringence optical property, used to visualize interference colours (anisotropism) by turning the stage of the microscope; caused by double refraction of light under crossed polarizers and consequent polarizing of the bundles of light
  • cutan accumulation of material on or against structural elements, walls of pores, etc. in soils or sediments; can be the result of illuviation or crystallisation
  • cryoturbation the mixing of soil or sediment beds as a result of repeated freezing and thawing and/or the disappearence of permafrost
  • deformable bed glacier bed which as a result of the glacial stress field is deformed and thus delivers part of the forward motion of the glacier
  • diagenesis all the chemical, physical or biologic changes undergone by a sediment after its initial deposition
  • Diamicton a generic term referring to any non-sorted or poorly-sorted, heterogeneous sediments containing a wide range of particle sizes in a muddy matrix and used when the genetic history of the sediment can not be ascertained. (adapted from the American Geological Institute’s Glossary of Geology (3rd edition; 1987)
  • domains small zones in which clay particles are oriented parallel to each other, causing them to behave (optically) like one single crystal
  • fissility property of some rocks of splitting easily into thin layers along closely spaced, roughly planar and approximately parallel surfaces
  • flowtill till that maybe derived from any glacial debris upon its release from glacier ice or from a freshly deposited till, in direct association with glacier ice
  • glaciomarine the environment where sediment is deposited in the sea after release from glacier ice or sea ice.
  • iceberg scour digging action of an iceberg on seabed or lakefloor
  • intraclasts torn-up and reworked fragment of unconsolidated sediment
  • lodgement till till deposited by plastering from the sliding base of a moving glacier by pressure melting and/or other mechanical processes
  • matrix see plasma
  • melt-out till till deposited by a slow release of glacial debris from ice that is not sliding or deforming internally
  • micromorphology microscopic examination of the composition and constituant structural elements of lithified and unlithified earth materials
  • pedology the study of soil morphology, genesis and classification
  • plasma originally particles of colloidal size (< 2 μm); may consist of clay minerals, oxides and hydroxides of Fe, Al and Mn, soluble salts, etc.; in micromorphology it is often used as synonimous with matrix which is all material smaller than the thickness of the thin section and in which, consequently, individual particles can no longer be seen
  • plasmic fabric (p.f) birefringence models of the plasma, based on the optical properties of the particles as well as the optical properties caused by the orientation of particles relative to each other;
  • asepic very few or no anisotropic plasma domains are present;
  • skelsepic plasma particles are oriented around a skeleton grain;
  • silasepic oriented particles occur only in isolated spots; silt sized material is dominant;
  • argillasepic oriented particles occur only in isolated spots; clay sized material dominant;
  • (bi)masepic short plasma domains are mainly oriented in bands in one (masepic) or two (bimasepic) directions; in laminated sediments it is parallel to bedding;
  • unistrial anisotropic clay with discrete, thin, continuous (i.e. long) birefringence bands in one direction;
  • lattisepic plasma separations occur in two, very short, and discontinuous sets, usually oriented approximately at right angles to each other, now thought to be an artifact of the optical system of the microscope;
  • omnisepicplasmic fabric domains show a full spectrum of oriented directions, irrespective of turning the stage;
  • kinkingorientation of domains is organised in alternating clear and dark parallel bands, caused by a fishbone arrangement of clay particles as a result of compression;
  • silt droplet concentrations of silt in (sub-)horizontal bands as a result of the formation of ground-ice (segregation) lenses
  • skeleton (grains) single grains which are larger than the thickness of a thin section and thus can be studied individually