Note: See Search for references not found here.
accommodation space: space made available for sedimentation below water level.
adhesion ripples: small-scale structures produced by wind blowing sand on a wet surface.
aeolianite: see eolianite.
agglomerate: conglomerate composed of mixed volcanic derived materials.
aggradation: vertical accretion of sedimentary interface; cf. lateral growth, progradation.
air-heave structure: distortion of depositional structures (e.g., laminae) by ascending gas.
aklè dunes: fields of barchan dunes; see color photo 11.
algal biscuits: old term for algal (or bacterial) encrusted grains; see oncoid, oncolith, and rhodolith; also see plate 144.
algal lamination (structure): synonymous with the more modern term bacterial lamination (structure); see also algal mat, oncolite, rhodolith, stromatolite.
algal mat: should be updated into bacterial or microbal mat.
allogenic: attribute of material deriving from outside the basin or the region; syn.: extraformational, extrabasinal, exotic, allochtonous, allotigenous, terrigenous.
alluvial: pertinent to fluvial deposits.
amalgamation surface: subdued bed surface of erosional origin separating two coarse-grained beds; erosion caused the welding of two similar or identical lithotypes.
anastomosing ridges: small-scale markings made by currents on the surfaces of sand or silt laminae (intrastratal or parting-plane structure).
anastomosing rill marks: morphological variety of rill marks: see color photo 19.
angle of repose: critical angle of slope of a loose sediment, representing an equilibrium condition between gravity (tangential component of weight) and internal resistance to shear (angle of internal friction).
antidunes: tractive bed forms formed in supercritical flow regimes; see plate 37.
antidune phase: range of hydraulic conditions favorable to formation of antidunes.
antiripples: see adhesion ripples.
appositional fabric: spatial arrangement of sedimentary particles following deposition; cf. imbrication.
arcuate bands: intersections of foreset laminae (cross-lamination) with the base of the bed; syn.: rib-and-furrow structure.
armored mudballs: sand or pebble coated mud clasts; see plate 80.
asymmetrical ripple marks: small-scale bed forms produced by a unidirectional current or waves with a dominant component of oscillation.
asymmetry index: descriptor of ripple asymmetry, equal to the ratio between the lengths of the two sides.
attachment point: where flow lines come in touch with a solid boundary after losing contact with it before or behind an obstacle; down current limit of a separation bubble; cf. separation point.
auto-breccia: breccia formed during lava consolidation, by rapid quenching or detachment of consolidated portions and their incorporation in the still fluid mass.
avalanching: sliding of groups of grains on the slipface of a bed form.
backfilling: retrogradational filling of a channel or scour; see plate 75 A.
backreef: internal, protected part of an organic reef, usually occupied by a lagoon.
backset beds (laminae): up current dipping beds (laminae).
backshore: emerged part of a beach; cf. foreshore; shoreface.
ballistic ripples: eolian ripples produced by saltating sand grains.
barchanoid (ripples, dunes): see under lunate.
base-absent sequence: bouma sequence lacking one or more lower terms; cf. bouma sequence, turbidite,
base surge: type of pyroclastic flow (turbulent suspension), driven by gravity and volcanic blast.
beach cusps: series of small "promontories" alternating with rounded embayments, which form along a beach (foreshore) in the wake of storms.
bedding plane structures: see external structures, interfacial structures.
bedform lag: delay between the discharge peak of a tractive current and the maximum development of related bed forms.
bedload: the bulk of particles transported near the bottom by a current.
bedset: packet or bundle of conformable beds.
berm: shallow ridge, bench, or terrace, separating foreshore from backshore.
bioconstruction: building up caused by active growth of colonial, sedentary organisms.
biodeformation: see bioturbation.
bioglyphs: see ichnofossils, trace fossils.
bioturbation: mechanical disturbance and deformation of sediment induced by organic activity.
bird's-eye (birdseye) structure: internal cavity related to desiccation, leaching, bioturbation, or early diagenesis of carbonate sediments; usually preserved by cement filling.
blanket: extensive deposit of reduced thickness.
blow-out: erosional channel form produced by wind.
bottomset: horizontal set of beds or laminae at the toe of foresets.
boudinage: deformation due to stretching and shearing of competent beds, induced by extensional tectonics, or detachment of slide masses (slumping); syn.: pull-apart structure.
Bouma sequence: vertical sequence of structures in a turbidite layer; a complete sequence consists of five intervals, or divisions (a through e).
bounce cast: a type of tool mark.
boundary shear stress: tangential pressure transmitted by a fluid to the interface with a solid or other fluid.
brush cast: a type of tool mark.
burrow mottling: patchy structure due to burrowing (bioturbation).
cabbage-leaf casts: see frondescent marks (plate 97).
calcrete: calcareous crust in soil of arid-semiarid zones; see duricrust.
calc-sinter: speleal encrustation, i.e., stalactite, stalagmite.
caliche: synonymous with calcrete.
candle-end flute casts: morphological variety of flute casts.
carbonaceous: rich in vegetal organic matter.
carrying capacity: capacity of sediment transport of a current.
cascade folding: folding style common in slumps and slides.
channel deposits: sediments confined in a stable or migrating channel; coarse materials represent bars formed when the channel is active; finer materials plug the channel after its abandonment.
channel fill: broadly speaking, synonymous with channel deposits; in a more strict sense, materials deposited after the channel has been disactivated.
channel-form: channel-like profile preserved in stratigraphic sections.
channelized deposits: see channel deposits, channel fill.
channel-lag deposit: coarse materials paving the bottom of a channel.
chaotic deposits: breccia, debris flow deposits, slumped beds.
charcoal lineation: streaks and laminae of carbonized vegetal debris.
chatter marks: scratches or cracks made on a rock surface by a mass moving over it; can be either a sedimentary structure (made by glaciers or debris masses) or a tectonic structure on a fault plane.
chevron fold: also called zigzag fold; a tectonic structure.
chord: distance between adjacent crests of ripples, dunes, or other bed forms; equivalent term: (wave) length.
chott: coastal lake, sabkha (north African term).
chute: minor channel incising a fluvial bar.
chute-and-pool structure: erosional bed form of upper flow regime; similar to truncated dunoids.
clastic dike: sedimentary dike constituted by clastic sediment.
clastic sill: concordant injection of clastic sediment.
clast supported: clastic fabric in which framework grains are in mutual contact.
clay ball: clay pebble, globular chip.
clay chip: intraformational clast made of clay or mud; cf. intraclast.
clay dune: eolian dune made of clay fragments.
climbing surfaces: surfaces connecting the stoss sides of climbing ripples; a type of false bedding.
clinostratification: inclined stratification (bedding), diagonal stratification (bedding); includes frontal, or progradational types (foreset bedding), and lateral, or transversal types (epsilon cross-bedding). The term should be used only for large bodies (vertical scale exceeding 1 meter), otherwise it is more properly defined as tabular cross-bedding.
coarsening up: upward increase in grain size in bedsets and sedimentary bodies, not in individual beds (where the term inverse grading should be used).
coastal drifting: long shore transport.
coastal sabkha (sebkha): arid-land coastal plain encrusted by salt, with diagenetic (vadose) precipitation of evaporites.
coated grains: particles surrounded by one or more envelopes of biological, chemical, or biochemical origin; they include oncolites, rhodoliths, ooids, oolites, pisoids, pisoliths.
collapse breccia: fragments due to roof falling in a cavity created by dissolution of buried beds; syn.: karst breccia; solution breccia.
comet-shaped flute casts: morphological variety of flute markings.
compaction: consolidation of sediments under load, with loss of fluids and pore space.
competence: the term can have a hydraulic or rheological meaning; in the first respect, it indicates the maximum velocity of a current (related to the size of transported particles); in the second, it is equivalent to strength or resistance to deformation. A competent bed, or material, can have a ductile, a brittle, or a mixed behavior.
complex ripple marks: see interference ripple marks.
cone-in-cone: load structure consisting of stacked cones pointing downward; it is found in mudstones, shales, and coal. The conical surfaces are surfaces of shear.
contourite: deposit of a contour current (deep-water thermoaline or geostrophic circulation).
coquina: shell bed.
corkscrew flute casts: morphological variety of flute casts.
corrasion ripples: structures similar in shape to ripples on rock surfaces, caused by mechanical (tectonic, glacial) or chemical action.
coset: group of sets of cross beds or cross laminae.
crawling trails: traces made by reptating organisms.
creep, creeping: slow mass movement of particulate material controlled by gravity on slopes.
crescentic ripple marks: lunate ripple marks.
crest lines: lines separating lee side from stoss side in ripples, dunes, and other bed forms.
crevasse splay: apron or lobe of sediment got out of a channel through a breach (crevasse).
crinkles: small or microscale folds.
critical slope: see angle of repose.
cross-grooves: groove marks that intersect each other (usually at angles less than 40°).
crumpled ball: ball-and-pillow structure, slump ball.
curled mud flakes: mud curls, curled mud polygons; structures related to desiccation.
current crescents: crescent marks.
current lamination: lamination produced by a tractive current.
current lineation: alignment of grains or other objects parallel to a current.
cuspate ripple marks: see under linguoid.
cut-off: erosional event that leaves a segment of a fluvial channel isolated from the main course.
cycloid: corresponds to ball-and-pillow structure, but has been interpreted as liquefaction structure and attributed to earthquake shocks.
datum: correlated stratigraphic level based on physical (lithological, geometric) evidence or data interpretation (biostratigraphic, magnetostratigraphic, etc.).
debris flow: gravity flow where fine particles and water form a single phase (mud), which can support coarser, usually heterogeneous materials; see also mud flow.
debris line: landward boundary of storm waves, underlined by debris of various origin.
deep-sea fan: submarine fan, built by turbidity currents and other mass flows.
deformed cross-bedding: deformations include over steepened foresets, folded foresets (gravity failure) and "hooked" tops (current drag).
dendritic rill marks: morphological variety of rill marks; see plate 85 and color photo 25.
depocenter: area of maximum accumulation within a basin.
depositional interface: upper surface of newly deposited sediment; ground surface in subaerial conditions, bed in rivers, bottom in subaqueous environments.
depositional strike: direction of contour lines on a slope; direction perpendicular to flow vectors in gravity controlled movements.
desiccation breccia: layer of mud completely broken by subaerial cracking; see color photo 27.
desiccation polygons: polygonal mud crusts delimited by desiccation cracks; syn.: mud crack polygons.
detachment point: see separation point (hydraulic concept).
detachment surface: surface from which a slide or slump detaches; see slide scar, slump scar.
dewatering: more or less violent expulsion of water from a compacting sediment.
diagenetic environment: physical and chemical conditions of buried sediments, especially localized in pores and vugs.
diagonal bedding: see clinostratification; the term should not be used for ordinary cross-bedding.
diamictite: mudstone with matrix-supported ruditic clasts (angular or rounded, indifferently), in all possible proportions. When pebbles are dominant, the term pebbly mudstone is also used.
diamicton: unconsolidated sediment with admixture of fine and coarse materials.
diapiric structures: domes and other structures related to salt injection in overlying beds (and possibly, surface outpouring and flowage).
diastem, diastemic surface: interruption of sedimentation, surface of stratigraphic discontinuity. It is an old term, coined when sedimentation was conceived as a continuous process, to stress gaps. Now, all bedding surfaces are regarded as diastems.
dip: orientation (immersion) of an inclined plane; can be primary (depositional) or secondary (tectonic).
disorganized: attribute of a ruditic sediment or rock, when there is no order in the arrangement of clasts; syn: chaotic.
distal: far from the source or the entry point (see ) of clastics.
domichnia: ecological type of trace fossil, or ichnofossil, left by organisms in living position; see dwelling burrow.
downlap: basal contact of a set of inclined beds on a horizontal or less-inclined surface.
downward shift: seaward displacement of the shoreline, regression.
draa: eolian dune of large size and complex structure.
drag fold: minor fold due to relative movements of competent and incompetent beds.
drag mark: mark left by an object dragged at the base of a flow; syn: groove cast, chevron cast.
drag wrinkles: small-scale soft-sediment deformation produced on a surface by friction with a moving mass.
drape: sediment cover of a rough substratum; mud cover on a coarser sediment.
dripstone: calcareous encrustation formed by dripping water in caves; includes stalactite and stalagmite.
dropstone: coarse particle dropped by rafting bodies (icebergs, trees, etc.) on subaqueous sediments.
dune bedding: cross bedding at a scale of a dune. The term is imprecise, because subaqueous dunes have an arbitrary upper limit of 1 m in height, whereas there is no limit for eolian dunes.
dunelike form: see dunoid.
dune-phase: range of hydraulic conditions allowing the formation of dunes on the bottom.
dunoid: dunelike bed form common in pyroclastic deposits. The profile is either symmetrical or asymmetrical, the internal laminae dip down flow but with an angle smaller than that of repose. The form can be truncated by erosion on the back side.
dwelling burrow: ecological type of trace fossil; see also domichnia.
edgewise (conglomerate, coquina): subvertical disposition of coarse particles in ruditic sediments and shell beds.
effective pressure (load): vertical pressure exerted by a submerged sediment, where only the weight of solid particles is effective (water pressure is neutral); represents the active force of compaction.
elutriation: mechanical selection, or particle sorting, made by an ascending fluid.
elutriation pipe: vertical structure in pyroclastic deposits, where fine ash particles have been removed by ascending gas.
entrainment threshold: critical value of shear pressure transmitted by a fluid to remove a stationary particle.
entry point: point source of sediments along a basin margin (shoreline or base of slope).
eolianite: cemented eolian (dune) deposit.
episodic: sporadic; in sedimentology, can be synonymous with catastrophic.
epsilon (cross)bedding: diagonal bedding caused by lateral (across-flow) accretion.
escape burrow: trace left by an animal trying to keep pace with rapid sedimentation.
esker: localized sedimentary body accumulated by melting water in a glaciated area.
evaporite: sedimentary rock constituted by salts precipitated from a solution because of evaporation of water.
evaporite solution breccia: collapse breccia due to the subsurface dissolution of evaporites; can remain as the only witness to vanished evaporites.
external structures: structures present on bedding surfaces; also interfacial structures
extrabasinal: deriving from outside the basin; cf. alloch- thonous, intrabasinal, terrigenous.
fabric: spatial arrangement of sedimentary particles (the term is used as well in igneous and metamorphic rocks). Sedimentary fabric is related to sedimentary processes (ex. : imbrication).
faceted pebble: ventifact, pebble shaped by wind.
facies: 1) lithological, textural, structural, and geometrical characters of a generic deposit (descriptive concept); 2) the same features as indicators of a type of process or environment (genetic, process-oriented concept); 3) features of a specific sedimentation event or episode (genetic concept, space and time dependent).
facies analysis: sedimentological analysis carried out in the field, based on macroscopic characters of sediments.
facies association: genetically and spatially related facies forming a sedimentary body or part of it, and reflecting a sedimentary environment or subenvironment.
facies tract: lateral sequence of genetically related facies.
fair weather deposits: beach sediments whose characteristics are controlled by normal waves; opposed to storm deposits.
fall velocity: important parameter for defining the hydraulic size of sedimentary particles; not to be confused with the velocity of sedimentation, or accumulation rate.
false bedding: pseudo stratification simulated by tectonic joints, cleavage, schistosity or sedimentary structures; see also climbing surfaces.
fan delta: coarse-grained delta fed by a torrential stream.
fanglomerate: coarse, poorly sorted conglomerate deposited in an alluvial fan or fan delta.
fan-shaped flute casts: morphological variety of flute casts.
feather marking: syn. of frondescent casts.
feeding burrow: ecological type of trace fossil.
feeding trail: ecological type of trace fossil (on bedding surfaces).
festoon: syn. of trough, the basic unit of concave cross-bedding; festoon cross-bedding = trough cross-bedding.
fining up: upward decrease of grain size in a sequence, or set of beds (not in individual beds, where the term normal grading should be used).
fissile: attribute of flaggy or laminated rocks with numerous parting planes.
flame structure: pointed pelitic injection; associated to load structures.
flaser bedding: thin, concave-up mud(stone) lenses within sand(stone).
flash flood: instantaneous flood surge in ephemeral streams of semiarid regions.
flat festoons: see swale, swaley cross-bedding.
flat-pebble conglomerate: intraformational conglomerate whose clasts derive from thin crusts or brittle, early indurated sediments.
flat-topped ripple marks: modified ripples with truncated crests.
flint: chert, crystalline silica.
flow regime: hydraulic condition defined by the Froude number, approximated by the ratio between velocity and depth (thickness) of a current, e.g., lower (subcritical) and upper (supercritical) flow regimes.
flow roll: syn. of pseudonodule, ball-and-pillow, slump ball.
flow separation: detachment of flow lines and fluid shear from the boundary; cf. attachment point, separation point.
flowstone: calcareous deposit encrusting cave walls or paving cave floors, caused by water flowing along them; cf. dripstone.
fluidal structures: generic term for whirling traces in deformed sediments.
fluidization: mixing of gas and solid particles that creates a phase behaving like a liquid; process occurring in pyroclastic flows.
foam marks: delicate structures (wrinkles) in littoral sands; similar to current markings on lamina surfaces of turbidites.
foredune: sand mound behind grass tufts or other obstacles in backshore zones.
foreset bedding: basinward dipping beds accumulating on a submerged slope.
foreshore: intertidal zone of a beach; its upper part is the swash zone.
form set: set of laminae recording a bed form in section.
founder breccia: see collapse breccia.
fragmented bed: bed with a chaotic, or disorganized, internal structure.
freezing: consolidation of a moving sediment-fluid mixture.
frost cracks: structures related to cryoturbation.
furrow: elongate erosional mark; see ridge-and-furrow structure.
gas hole: surface expression of escaping gas; on a large-scale: pockmark.
gas pit: see gas hole.
Gilbert delta: fan delta advancing in a relatively deep body of water. The resulting geometry shows a typical "triad": topset, foreset, and bottomset beds (see color photo 2); see clinostratification, fan delta, progradation.
glacial flutes: marks made by glaciers on bedrock, similar to current-produced flutes in sediments.
glacial striation: drag structures made by glaciers on both sediment and rock.
glaciotectonic structures: soft-sediment deformation caused by overriding ice.
glide breccia: breccia caused by sliding or tectonic friction.
graded bedding: fabric expressing vertical grading.
graded interval (division): basal part of the Bouma sequence.
grading: vertical or areal variation of grain size in beds, layers, and laminae, i.e., in individual depositional units; can be normal or reverse (inverted).
grain fall: gravity-driven deposition of individual particles at the foot of slopes and cliffs; cf. rockfall.
grain flow: collective movement of solid particles behaving like a fluid.
gravel stripe: alignment of pebbles parallel to current or wave motion.
grazing mark: scratch made by an animal on the bottom surface; trace fossil related to feeding or crawling activities.
ground surge: type of pyroclastic flow, observed for the first time at the base of ascending columns in experiments with atomic bombs.
growth fault: normal fault induced by gravity on the margin of a basin (downthrown side is basinward).
growth model: mode or style of accretion of a sedimentary body; examples are aggradation, progradation, frontal accretion, lateral accretion.
gully: minor channel on a slope.
hailstone imprints: small pits similar to raindrop imprints, preserved in fine sediments; also (syn.) pitted mud.
hemipelagic: attribute of fine sediments composed partly of indigenous (intrabasinal) particles, like microfossil tests, and for the other part by terrigenous (land derived) or extraformational (from older geologic bodies) materials.
herringbone: attribute of a variety of cross-bedding.
heterolithic: attribute of a facies showing more than one lithology; virtually restricted to sand(stone)/mud(stone) alternations; cf. rhythmic bedding, rhythmite.
hexagonal cross-ripple marks: see interference ripple marks, tadpole nests.
hiatus: discontinuity of sedimentation, stratigraphic gap.
hieroglyph: old name for sole marking.
horizontal lamination: the term should be used only in Modern and Recent sediments. In Anciet sediments, use plane-parallel lamination, bed-parallel flat lamination.
host sediment: sediment embedding secondary structures; see diagenetic environment.
hydraulic jump: local hydraulic instability of a current owing to sudden increase in thickness and/or change in gradient.
hydraulic size: fall velocity of a sedimentary particle, controlled by size, weight and shape.
hydraulic sorting: grain selection based on hydraulic size.
hydroplastic deformation: ductile deformation in water-soaked sediments..
hydrostatic pressure (head, load): pressure exerted by water (in all directions).
hypersaline: marine water with salt concentration above normal.
hyposaline: marine water with salt concentration below normal; syn.: brackish.
ice-crystal marks: indicators of cryoturbation.
ice-push structures: see glaciotectonic structures.
ice-rafted sediment: includes dropstones.
ice ripples: undulations on ice surface due to contact with water.
ice-shear structures: see ice-push structures.
ice-wedge polygons: polygonal zones of a ground or soil delimited by ice wedges.
ice wedges: ice-filled cracks in frosted soil or sediment.
ichnofossil: trace fossil, organic structure modifying a sediment.
imbrication: shingled arrangement of platy particles, produced by currents or waves.
impact marks: traces left by impacting objects on sediments.
inclined bedding: see clinostratification. These terms imply depositional slopes; for inclination of tectonic origin, use tilting.
incompetent: easily deformable material.
indicator: sedimentary character that records a specific mechanism, process or environment.
infauna: benthic animals living inside the sediment.
injection structures: deformation structures related to upward intrusion of various materials: water (see dewatering), quicksand, fluid mud, plastic mud, salt; also sedimentary dikes, sedimentary sills, diapiric structures, liquefaction structures, fluidization structures, dish structure, pillar structure, and others.
inland sabkha (sebkha): subbottom of a dried lake, with salt encrustations; cf. playa lake.
interfacial structures: marks, imprints on bedding planes.
interference ripple marks: a rippled surface with different orientations of ripple crests.
internal sediment: particles that infiltrate in a porous sediment or a leaching cavity.
intertidal: comprised between average high tide mark and low tide mark.
intertonguing: interfingering of depositional units (regardless of scale).
intrabasinal: relates to materials and phenomena originating within a sedimentary basin; cf. allochthonous, extrabasinal, terrigenous.
intraclast: clastic particle deriving from fragmentation of intrabasinal sediment.
intraformational: deriving from intrabasinal reworking.
intrastratal: internal to beds or layers. Examples: intra- stratal solution, intrastratal structure.
inverse grading: upward increase of grain size within a bed or layer; cf. coarsening-up.
jet: expanding flow.
joint: fracture, surface of tectonic discontinuity without displacement of parts.
jo;aukulhlaup: Icelandic term for catastrophic flood deriving from the collapse of an ice dam.
kames: morphological and sedimentary unit deriving from deposition by melting water in glaciated areas; cf. esker.
kankar: calcareous duricrust.
karst: subterranean cavities in soluble rocks; also cave deposits, dripstone, flowstone, speleothems.
keeled ripple marks: morphological variety of r.m.
key bed (layer): bed (layer) used as a marker for stratigraphic correlation; corresponds to a time line or synchronous stratigraphic level.
kinetic sieving: downward shift of fine particles between larger ones in a moving sediment.
lag (conglomerate, deposit, pavement): coarse particles lagging behind most currents which are not able to carry them. More or less continuous cover of erosional surfaces (except cut-and-fill scours).
lahar: dry or wet avalanching (debris flow) of remobilized volcanic ash, often embedding coarse particles; cf. pyroclastic flow.
laminar sublayer: part of a boundary layer in close contact with the boundary, where the flow is laminar (not turbulent).
laminaset: packet or bundle of conformable laminae.
lateral growth: mode of accretion of a sedimentary body.
layer-cake: a growth model, with vertically accreting, parallel, continuous layers.
leaching vug: see birds-eye structure.
lebensspuren: German term for trace fossils.
lee side: frontal or anterior side of a bed form.
lensing: thinning at both sides of a bed or a body.
lenticular bedding: alignment of sand(stone) lenses embedded in mud(stone).
levee: natural or artificial super elevation of a channel bank. Natural levees are built by overflowing sediment.
linear structures: structures reflecting the trend, but not necessarily the direction of a movement.
lineation: linear structure parallel to movement.
linguoid (bar, dune, ripple): morphological variety of a bed form; syn.: cuspate.
liquefaction: process destroying the solid framework of a water-saturated sediment and creating a mixture with the behavior of a liquid.
lithosome: rock body.
lithostatic pressure (load): vertical pressure exerted by rock bodies, including the solid particles of sediments.
lithotope: part (area) of a sedimentary environment characterized by a certain lithology.
load: static pressure due to weight.
load-casted (flute cast, groove cast, etc.); sole markings emphasized by load effects.
longitudinal: parallel to a movement or to the length of an object; e.g., longitudinal bar, longitudinal section.
longitudinal furrows and ridges: type of wrinkle marks; see ridge-and-furrow structure.
long shore bar: submerged littoral bar, parallel to shoreline.
long shore current: current parallel to shoreline, developing in beaches where and when waves impinge obliquely.
low-angle (cross-bedding, cross-lamination): inclination smaller than the angle of repose in laminae or beds.
lower flow regime: see flow regime.
low-flow structures: structures associated to bed forms of lower flow regime.
lumpy bedding: see mottling, nodular bedding.
lunate (ripples, dunes): morphological variety of bed forms; syn.: barchanlike, barchanoid.
lunette: see clay dune.
maar: see tuff ring.
marker: correlatable stratigraphic horizon, recognizable in the field; cf. datum; key bed.
mass flow: flow transporting high quantities of sediment per unit area and unit time. It can be fluid or gravity driven.
massive: ambiguous attribute, used both for thick or very thick beds and for the lack of structures (the two characters often coincide but should be kept separate).
matrix: finer material in sediments with two size modes, filling pore spaces or embedding coarser particles.
matrix-supported: surrounded, embedded by matrix.
meander: loop of a migrating channel with high sinuosity.
meander scroll: see scroll bar.
megaripple: long ripple or subaqueous dune.
micrite: microcrystalline calcite deriving from crystallization of carbonate mud; opaque in thin section, whitish in outcrop and polished section.
microdelta: modification structure observed in intertidal environments and looking like a small-scale delta; see plate 29.
mima mounds: patterned ground with moundlike relieves made of silt; attributed to cryoturbation or earthquakes; occur mostly in cold regions.
mottling: patches of different color or texture due to bioturbation or diagenetic reactions (nodule growth, etc.).
mud ball: see clay ball, mud pebble.
mud clast: intraclast, clay chip.
mud crack: desiccation crack.
mud-draped ripples: ripples with tops preserved by a mud cover; see plate 58.
mud flat: mud-covered part of a tidal or coastal flat.
mud flow: end member of debris flows (no clasts).
mud lump: top of a mud diapir.
mud mound: micritic mass accumulated by organisms.
mud pebble: rounded mud clast; see also clay ball.
mud pellet: see mud pebble.
mud ripples: undulations on mud surfaces subject to current or wind shear; a rare structure.
mudstone: fine-grained rock, or compacted sediment, with no obvious fissility; textural term, independent from composition.
mudstone conglomerate: see intraformational conglomerate.
mudstone pebbles: rounded intraformational clasts.
multiple grading: repeated grading; can occur in laminae within beds or in amalgamated beds within a bedset.
nodular bedding: pervasive nodular structure that destroys original bedding; see plate 171.
nodule: structure of chemical or biochemical origin; small mass of amorphous or crystalline mineral growing within a host sediment.
normal grading: upward decreasing size in a clastic bed or layer; cf. fining-up.
obstacle shadow: sediment accumulation behind an obstacle.
offshore bar: sedimentary relief on a shelf, separated from the littoral zone.
olist(h)ostrome: slid mass or big debris flow deposit (not clear in the original definition).
oncoid: see oncolith.
oncolith: grain coated by calcified microbal laminae.
oncolitic structure: concentric structure of oncoliths.
onlap: a type of discordant contact; beds leaning against an inclined surface.
organic mound: sedimentary relief caused by building organisms; e.g., reef, bank, mud mound, stromatolitic mound.
organized: attribute of a coarse clastic deposit, in which the particles are arranged with some order (layering, size or shape sorting, imbrication).
oscillation ripples: wave ripples.
outwash deposits: glacio-fluvial sediments.
overbank deposits: fine sediments overflowed from channels.
overfold: overturned fold, often occurring as a broken, uprooted hinge in slides.
oxbow lake: abandoned meander loop.
packing: "geometric" density of grains; ratio between volume of framework grains and total sediment volume.
parabolic dune: type of coastal dune with slipface convex downwind (opposite to barchan dune).
paralic: attribute of coastal to shallow water environments, or facies; syn.: marginal marine.
parallel lamination: plane or wavy, continuous lamination.
parting plane lineation: alignment of grains or objects on an intrastratal surface (parting plane).
parting-step lineation: parting lineation with shallow terraces.
pebbly mudstone: type of diamictite. The origin can be glacial (till), glacio-marine or glacio-lacustrine (dropstones) or related to mass flows.
penecontemporaneous: early post-depositional.
penecontemporaneous deformation: see soft-sediment deformation.
permafrost: permanently frosted ground.
phacoidal: peculiar shape of intraformational fragments.
phreatomagmatic: qualifies an explosive eruption involving water bodies.
pillar structure: small-scale sedimentary dike within sandstone beds, commonly associated with dish structure.
pinch-out: lateral termination (wedging) of a bed or sedimentary body.
pit-and-mound structure: see gas hole, gas pit.
planar cross-bedding: geometrical variety of cross-bedding, contrasted with trough (concave, festoon) cross-bedding; syn: tabular cross-bedding.
plane bed: flat depositional interface, with no fluid movement over it or a current in upper flow regime.
plane bed phase: range of hydraulic conditions preventing formation of bed forms.
platform: environment of shallow water carbonate deposition.
playa lake: ephemeral lake of semiarid regions; cf. inland sabkha.
point bar: laterally accreting bar in a meander loop; cf. epsilon (cross)bedding.
polygonal ground: patterned ground of subpolar regions characterized by alternating freezing and thawing; cf. ice-wedge polygons.
preservation potential: determines the absolute and relative abundance of structures that are recorded in sedimentary rocks, with respect to the total original number.
priel: erosional structure at the base of beds; examples: scour, gutter cast.
primary lineation: see parting plane lineation.
prismatic cracks: variety of desiccation cracks.
problematic markings: sole marks of unexplained or not completely clear origin.
prod marks: morphological variety of impact markings.
progradation: a growth model of sedimentary bodies; lateral (frontal) accretion in a water body. Frontal means "in the direction of main flow vector and sediment supply," in contrast with transversal, or normal to flow vector; cf. clinostratification, foreset bedding, Gilbert-type delta.
prograding: advancing basinward.
progressive cross-bedding: syn. of climbing ripple cross-lamination.
proximal: close to the source or the entry point (see ) of clastics.
proximal rim: upcurrent margin of a structure.
pseudo bedding: see false bedding.
pseudo breccia: old term for breccias of nondepositional origin.
pull-apart (basin): basin originated by wrench, or transcurrent faulting.
pull-apart (structure): extensional deformation; see boudinage.
pyramidal dune: a morphological variety of eolian dune; syn.: star dune.
pyroclastic flow: broadly speaking, any dispersion (solid-fluid mixture) of volcanic ash and hot gases flowing under the control of gravity; strictly speaking, a laminar nonturbulent flow with a high concentration of solid particles, similar to a debris flow.
pyroclastic surge (flow): highly turbulent pyroclastic flow with tractive power (cf. dunelike bed forms). Base surge and ground surge are two varieties.
quickclay: liquefied clay.
quicksand: liquefied sand.
radial: type of fabric or growth pattern in chemical and biogenic structures.
rafting: transport by floating objects.
reactivation surface: small-scale unconformity between foreset laminae.
reattachment point: see attachment point.
recumbent fold: overturned fold with horizontal or slightly dipping axial plane.
recurrence time: return time of an event.
recycled sediment: sediment deriving from erosion of an older deposit or sedimentary rock.
recycling: removing particles from an older sediment, extraformational reworking.
redeposition: deposition of sediment removed from a previous site of accumulation within the basin perimeter; cf. intraformational reworking, intrabasinal reworking.
resedimentation: redeposition caused by mass transport and catastrophic events.
residual angle (after shearing): slope angle assumed by a loose sediment after avalanching took place; cf. angle of repose.
resting tracks: ecological type of trace fossils, due to stationing animals.
reversed density gradient: cause of gravitational instability in stratified fluids or sediments; produces structures such as load casts, pseudonodules, flame structure, convolutions.
reworking: in paleontological jargon, remobilization of body fossils; in sedimentological terms, any action of mechanical or biological modification of a previous sediment.
rheotactic fabric: particles reoriented by a current after deposition.
rhodolith: calcareous nodular body produced by algal accretion around a nucleus.
rhomboid rill marks: morphological variety of rill marks; see plate 84.
rhomboid ripple marks: lozenge-shaped ripple marks.
rhythmic (bedding, lamination): regular repetition of a couplet, or a triplet, of lithologies.
rhythmite: rhythmically bedding or laminated deposit; the term is employed mostly for thin beds or laminae (e.g., varve).
ridge-and-furrow structure: variety of longitudinal sole marks, produced by "spiral tubes" (see ); preserved both as original (on parting surfaces) and as a mold.
riffle-and-pool: channel bed morphology in sinuous streams.
rill molds: variety of flute casts, mistakenly interpreted as molds of rill marks.
rim cement: crystalline coating of particle surfaces or cavity walls; passes into void or other type of (central) cement; present in geode, druse, hollow concretions.
rip current: return (seaward directed) current active after storms in littoral zones; it is laterally confined and can scour channels.
ripple crest: limit between the two oppositely dipping sides of a ripple (not necessarily the top).
ripple fan: set of "parasite" ripples flooring the trough before a dune; see plate 29.
ripple index: describes the basic shape of a ripple by the length/height ratio.
ripple-load convolutions: convolutions related to load-casting of rippled sand beds.
ripple trough the deepest part of a ripple.
rock avalanche dry or wet sliding of rock debris; a type of very coarse sediment gravity flow; sturzström (Swiss term).
rockfall downslope fall of fragments detaching from a rock mass (or an organic reef). Particle by particle gravity accumulation.
rockslide type of landslide; mass of rock sliding as a single block or in fragments (rock avalanche).
rollability propensity of sedimentary particles to roll.
roll casts marks made by rolling objects; a type of tool marks.
rootlet bed bed with fossil roots or root traces, often underlying a coal bed.
roughness asperities of a bed or solid boundary; in hydraulics, it is not the absolute relief that counts, but its relation with the flow depth.
roundness index measures the amount of abrasion on edges and corners of clastic particles.
ruffled groove cast groove cast with ``barbs'' on one or both sides, making transition to chevron cast; see plate 101.
runnel cast fill of an elongated scour at the base of a bed; see gutter cast.
runzelmarken German term for wrinkle marks.
sabkha salt flat with vadose evaporites; see also coastal sabkha, inland sabkha.
saltation mode of bed load movement, with grains lifted temporarily in the flow; particularly diffused in wind transport.
sandblasting a type of abrasion in eolian environments.
sand blow dewatering or liquefaction structure; see pillar structure, sand volcano.
sand boil see sand blow.
sand flat sand covered part of a tidal flat; see plate 28.
sand flow variety of grain flow, with sand moving like a fluid substance.
sand holes gas holes on a sand bed; see plate 149.
sand pipe see pillar structure.
sand ribbon thin, elongated sand body deposited by wind in subaerial environment or tidal currents in shallow submarine environment.
sand shadow sand accumulated behind an obstacle; cf. foredune; see color plate 12.
sand slough see sand blow.
sand spout see sand blow.
sandstone whirlball a spiraled variety of pseudonodule (pillow) or slump ball.
sandur glacio-fluvial plain.
sand wave large scale, subaqueous, migrating bed form made of sand(stone), produced by a tractive current.
sausage structure see boudinage.
scallop dissolution furrow, karren.
scour-and-fill scour immediately filled by sediment carried by the same scouring agent.
scour marking erosional mark carved by current eddies; includes flute mark, crescent mark, gutter cast, current crescent, moat, etc.
scour remnant ridges ``passive'' relieves contrasted with ``active'' ones caused by deposition or deformation.
scroll bar minor arcuate bar on top of a point bar.
sedentary benthos benthic organisms, individual or colonial, which remain fixed to the bottom.
sedimentary interface see depositional interface.
sedimentation event single act of deposition.
sedimentation episode sequence of events related to the same process or environment.
sedimentation unit the record of a sedimentation event, or episode; lamina, bed or layer, laminaset, bedset.
sediment flow see debris flow.
sediment wave large scale undulation of sea bottom due to a current; seismic reflectors reveal unidirectional migration.
seepage infiltration and percolation of fluids in the sediment pores.
seif longitudinal desert dune.
separated flow fluid shear transferred from the bottom to the fluid body.
separation bubble shadow zone on the down current side of a bottom asperity (roughness element), where a secondary circulation separates from the main flow.
separation point point of detachment of a separated flow, upcurrent limit of a separation bubble; cf. (re)attachment point.
separation zone see separation bubble.
shaling out lateral transition into shales.
shear (force, stress, strain): reciprocal mechanical action exerted by masses in relative movement parallel to their surface of separation (tangential).
shear plane see shear surface.
shear surface surface of separation of masses sliding one past the other.
shear strength resistance to tangential movements (sliding).
sheet shape of a layer, or sedimentary body whose areal extent is much prevalent on thickness.
sheet crack desiccation crack parallel to bedding.
sheet erosion instantaneous erosion caused by an unconfined current.
sheet flood flooding current not confined to a channel.
sheet flow unconfined flow, with limited depth relative to width.
shelly bed accumulation of organic (skeletal) remains.
shingle structure see imbrication, imbricated fabric.
shoreface permanently submerged part of a beach, beneath low tide mark.
shrinkage crack subaqueous crack caused by physiochemical contraction in a mud.
silcrete siliceous duricrust.
sinter chemical encrustation in springs, lakes, and streams; can be calcareous (travertine, encrusting limestone) or siliceous.
skeletal attribute of hard, mineralized parts of organisms.
skim mark syn. of chevron mark.
skip cast variety of impact tool casts.
slide scar bare surface left by the detachment of a slide.
slide sheet tabular accumulation of a slid mass.
slipface down current side of a bed form, where grain avalanching takes place.
slip plane (surface): surface of sliding, base of a sliding mass; cf. shear plane.
slump rotational sliding.
slump ball pillow structure entrained in slumping or sliding.
slump fold folding related to gravity sliding.
slumping see slump.
slump overfold overturned slump fold.
slump scar curve, spoon-shaped surface of detachment; see also slide scar.
slump sheet tabular accumulation of a slumped mass.
small-scale cross-stratification (bedding): cross-lamination, ripple cross-lamination.
soft-sediment deformation penecontemporaneous deformation, deformation occurring in the sedimentary environment or basin.
solifluction soil creep.
solution furrow surficial karstic feature; syn. : scallop, karren.
solution ripples surface karstsic feature; pseudo ripples caused by dissolution
sorting selective distribution of grains, based on size, shape, or weight.
sparite calcite in large, clean crystals.
spasmodic event catastrophic or episodic event, suddenly releasing a high amount of energy.
speleal related to caves, karstic.
speleothem cave deposit.
spiral tubes longitudinal vortexes, where fluid particles follow helicoidal paths.
splitting planes parting planes of fissile rocks.
spongy (texture, rock): vuggy.
spontaneous liquefaction see liquefaction.
spreiten (Ger.): minor biogenic structures associated with trace fossils.
spring pits small structures produced on the surface of beach sand by escaping water.
spring-neap cycle tidal cycle corresponding to half a month (lunar month =27.3 days).
spur accessory structure of ripple marks, parallel to the flow.
spur-and-groove morphology of the submerged rim of a reef.
squeezed mud ridges see flame structure.
stalactiform looking like a stalactite.
standing wave stationary undulation present on the surface of both water and water-sediment surface in the antidune phase (upper flow regime) of a tractive current. The sediment is in motion on the bottom.
star dune syn. of pyramidal dune; type of desert dune.
starved basin undernourished basin, basin with little input and/or production of sediment.
starved ripples ripples forming a discontinuous sand bed (the troughs are occupied by mud).
steady flow a flow whose configuration (expressed by the velocity profile) does not change with time.
stone cluster see pebble cluster (to be used for clasts larger than pebbles).
stoss side upcurrent side of a bed form.
straight crested ripples contrasted with sinuous and three-dimensional ripples.
streaked-out ripples old term for flame structure; nothing to do with ripples.
streamline flow line, connecting velocity vectors in the flow direction.
striae striations, scratches; delicate markings.
strike intersection between an inclined plane and the horizontal, e.g., depositional strike, tectonic strike.
stromatolite laminated structure deriving from lithification of an algal (microbial) mat.
structureless term recommended instead of massive, for beds of uniform or homogeneous texture.
sturzström Swiss term for rock avalanche.
subcritical flow regime: see flow regime.
sun crack see desiccation polygons, mud crack.
superposed ripple marks see interference ripple marks.
surge rapid uprising of energy, catastrophic wave or flow (in pyroclastic processes); cf. base surge, ground surge.
surge (flow) see pyroclastic surge.
suspended load the bulk of particles carried in suspension by a flow.
suspension current gravity driven (density) current in which the density contrast with surrounding fluid is created by suspended particles; cf. turbidity current, pyroclastic surge flow.
swale 1) furrow between scroll bars of a meander bar; 2) scour related to hummocky cross-bedding.
swaley cross-bedding a variety of trough cross-bedding with slightly curved concavities; erosional counterpart of hummocky cross-bedding; also known as flat festoon (bedding).
swash wave dying on the beach face.
swash zone upper part of the foreshore, delimited by the berm.
symmetrical ripple marks see oscillation ripple marks, wave ripples.
syndromous load-casts syn. of dendritic ridges-and-furrows.
syneresis subaqueous shrinkage of gel-like materials.
tabular cross-bedding planar cross-bedding.
tangential cross-bedding foreset bedding with asymptotic toe.
tectonic ripples pseudo ripples; tectonic crenulations simulating sedimentary ripples.
tempestite storm layer, storm deposit.
tephra ashfall deposits.
terrigenous deriving from land areas.
thin-out see pinch-out, wedging.
thixotropy property of colloidal substances, passing from gel to sol conditions when disturbed.
threadlike flute casts morphological variety of flute casts.
threshold of grain movement critical value of fluid stress for removing a grain from the bed; entrainment threshold.
tidal channel channel in a tidal flat or estuary; cf. tidal inlet.
tidal creek small channel in mud flats.
tidal delta splay or fan of sand at the mouth of a tidal inlet.
tidal inlet passage between barrier islands.
till glacial deposit.
tillite consolidated glacial deposit.
time-transgressive diachronous, crossing time lines (surfaces).
toeset deposit connecting foreset and bottomset beds (laminae).
tool marks marks made by objects transported by a current, a mass flow, a slide, or a glacier.
toplap upper contact of foreset beds (laminae).
topset upper part of the triad top-, fore- and bottom-set; see Gilbert delta.
trace fossils individual bioturbation structures.
track type of animal trace preserved on bed surfaces.
traction carpet layer of moving and colliding grains at the base of a flow; collective bedload movement.
tractive movement selective bedload movement in which particles follow individual paths.
trail type of animal trace preserved on bed surfaces.
tranquil flow regime lower flow regime.
transverse ribs sort of crude ripple-like bed forms built with pebbles.
travertine concretionary or encrusting limestone due to chemical precipitation in continental environments (lake bottom, river bed, springs). encrusting limestone, calcareous sinter, tufa.
trough depressed portion of a bed form; longitudinal scour.
trough cross-bedding morphological type of cross-bedding reflecting the migration of three-dimensional bed forms; see festoon, swaley cross-bedding.
truncation upper termination of depositional units caused by erosion.
tufa see travertine.
tuff ring circular rampart built by accumulation of pyroclastic products around a vent located in a lake or an area with abundant water in the subsurface; cf. phreatomagmatic; syn. : maar.
tumble marks marks made by jumping/rolling objects.
turbidite the deposit layer of a turbidity current.
turbidity current a type of subaqueous density current in which the excess density is created by suspended sediment.
turboglyphs old name for flute casts.
twisted flute cast morphological variety of sole marking.
twisted groove cast morphological variety of sole marking.
unconfined current current not bounded by a channel; sheet flow.
unconformity geometric discontinuity of sedimentological or stratigraphic nature.
undercutting erosion at the foot of a cliff or river bank.
undertow see rip current.
upper flow regime supercritical flow regime; see flow regime.
U-shaped burrow type of shallow-water burrow.
vadose zone subsurface zone above the water table.
varve annual or seasonal deposit, commonly rhythmic.
velocity profile line connecting velocity vectors in a flow section (longitudinal, transversal or horizontal).
ventifact stone or object sculptured by the wind.
vergence direction of tectonic transport in zones subject to compression and shortening, which result in folds and thrusts; applied by analogy in soft-sediment deformation caused by tangential stresses.
waning current current related to a catastrophic event, which looses energy after an initial peak.
wash-out see scour-and-fill.
washover fan lobate or fan-shaped deposit in a lagoon, caused by a storm breaching a barrier island.
watery slide see debris flow, grain flow.
wave base maximum depth of traction for waves. Three levels can be distinguished, with reference to fair-weather waves, average storm waves, and exceptional (storm, tsunami) waves, respectively.
wavelength crest to crest distance in periodical bed forms; chord.
wave-ripple lamination a morphological type of cross-lamination, reflecting wave ripples.
wave ripples ripples produced by wave action. Without specification, normal waves are understood (storm waves produce hummocky cross-bedding).
wavy bedding a member of the triad completed by flaser and lenticular bedding; alternating sand and mud beds are both continuous, with wavy surfaces due to ripples and load effects.
wavy lamination a variety of parallel lamination; cf. plane lamination; contrast with discontinuous (cross) lamination.
way-up criteria methods for reconstructing the stratigraphic polarity (up and down) in tilted or overturned strata.
weathering physical and chemical alteration of rocks exposed to the atmosphere.
wedging lateral thinning of a depositional unit or sedimentary body.
wedge-out see pinch-out.
wedge-shaped cross-bedding morphological variety of cross-bedding.
wind-drift current current stimulated by the wind blowing on a water surface.
wind ripples ripples on dry sand, mostly related to saltation mechanism; see ballistic ripples.
wingless flute casts incomplete flute casts.
winnowing cleaning of coarse sediment, selective removal of fine particles.
wrinkle marks delicate erosional or deformational marks, usually preserved on lamina surfaces within beds; type of intrastratal current marks; see also longitudinal furrows and ridges.
yield limit the stress at which a material begins to undergo permanent deformation.
yield strength see yield limit.
younging going up stratigraphically.
Y-shaped burrow type of vertical burrow common in shallow water.
zibar dune a type of desert dune devoid of slipface.