Glossary - Fundamentals of the Physical Environment - page 881

Crustal shortening Crustal compression and consequential thickening, achieved by
folding and thrusting, and associated particularly with convergent plate boundaries.
Crustal thickening An increase in crustal thickness caused by intracontinental thrusting
in an A-subduction zone, where the buoyancy of light continental crust precludes B-
subduction and resorption ; isostatic balance is maintained by the displacement of
denser crust below the thickened pile.
Crusting The reduction of soil infiltration capacity by surface compaction during heavy
rainfall, the dispersal of fine grains into pores and subsequent drying.
Crustose lichens Lichens with flat, crust-like growth form; lichens are symbiotic
associations between a fungus and an alga.
Cryofracture An alternative term for frost shattering .
Cryonival Said of processes related to the combination or close proximity of snow and
ice, such as frost weathering at the margins of a snow patch and driven by its diurnal
thaw-freeze.
Cryopedology Soil-forming processes occurring in low-temperature conditions, usually
in the presence of permafrost .
Cryophyte A cold-tolerant plant of the arctic-alpine community with life forms and
cycles adapted to persistent snow and ground ice.
Cryosphere The portion of Earth's hydrosphere where water is perennially frozen as
snow, glacier or ground ice .
Cushion mosses Mosses with erect stems.
Cut and fill The erosion and subsequent sedimentation of new fluvial channels cut
through existing fluvial sediments, and the sedimentary structures so formed.
Cyclical climax theory The theory of climax vegetation which emphasizes cyclical
rather than unidirectional change; mostly discussed in relation to tropical forests.
Darcy's law A definition of the relation between the transmission of water through
porous Earth material, water viscosity and the height of the free water surface above
the point of measurement.
Debris cone A cone-shaped mass of rounded boulders deposited where a mountain
stream meets a flat valley floor.
Debris flow A mass wasting process in which fluidized colluvium or other loose,
granular debris moves downhill in a series of rapid turbulent pulses.
Decalcification The removal of carbonates (mostly calcium carbonate) from a soil
horizon.
Décollement A zone along which overlying rocks or other Earth materials have become
detached from and have moved over underlying materials, normally as the materials
respond to shear stress.
Decomposers Organisms that feed on dead or decaying organic matter.
Deflation The removal by wind of fine granular materials, especially sand, silt and snow.
Deflation hollow A surface depression in a material which has undergone deflation or
been abraded by windblown sand.
Deformation The alteration of Earth material from an initial shape and internal structure,
involving compression, extension, folding , faulting , shear, etc.
Delayed flow An estimated component of stream flow which is delayed in reaching the
channel after a precipitation event but does not form part of the baseflow .