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Glossary
Accommodation - The space available for deposition. A principal control on the environment of deposition and ability of that environment to have net sedimentation, or preserve sediments and fauna in an environment.
Anoxic - Conditions in which there is little oxygen, and where this occurs on the seafloor, generally minimal bottom life. Less oxygen than dysoxic or dysaerobic.
Bioturbation - The mixing and moving of sediment by organisms. Distinct tracks, trails, dwelling structures, etc. are termed trace fossils or ichnofossils.
Buildup - General term for the geometric accumulation of sediment in a mound or pinnacle structure. Implies an upward building accumulation of sediment. In the Fort Payne, buildups are commonly called mud mounds, and consist of both siliclastic and carbonate muds.
Calyx - The cup-like crown or body of crinoids. Plural is "calyces."
Camerate crinoids - A large group of crinoids (a class of stalked echinoderm) in the subclass Camerata, which have a raised or domed tegmen (covering on the top of the crinoid's calyx or crown), generally thick plates, and rigid dorsal cups.
Carbonate bank - A large, broad, submarine geomorphic feature formed by an accumulation of carbonates (usually from sessile organisms). Also called a carbonate platform.
Carbonate ramp - A configuration of carbonate platform margin with a low-gradient depositional slope.
Carbonate slope - A broad, inclined submarine geomorphic feature connecting a topographically higher platform region to a topographically lower basinal region. Gradual slopes are termed ramps, while steeper slopes are sometimes referred to as bypass margins, because sediment is bypassed around them.
Clinoform - Geometric description of large-scale sediment packages that form where sedimentation mantles an inclined surface on which beds thin and pinch-out (downlap) onto the basin floor. Clinoforms are typical of the Borden and Fort Payne Formations.
Condensed section - In sequence stratigraphy, a fine-grained bed that accumulated over a long time. In many cases, the bed represents long periods with little or no deposition. Condensed sections are often laterally equivalent to very thick successions of strata in other areas. For example, the condensed section at the base of the Maury Shale or Maury-shale equivalent in Kentucky (less than a foot thick) represents most of the entire Borden Formation (hundreds of feet thick) in eastern Kentucky. For more information see SEPM's glossary of sequence stratigraphy.
Dasyclad algae - A unicellular green algae belonging to the order Dasycladales. These algae live in marine waters and have a calcium carbonate shell.
Debrite - The deposit of a debris flow. Clasts and grains in a debrite are matrix- rather than clast-supported.
Debris flow - A type of mass flow in which clasts are carried rapidly downslope in a liquefied state.
Downlap - A term to describe the geometric relationship between beds, in which an inclined bed pinches out down dip. Downlap, offlap, and onlap were used first to describe large regional relationships on seismic lines, but were then used for geometric relationship descriptions in sequence stratigraphy.
Dunham classification - A commonly used classification for describing limestones based on the amount of interstitial fine-grained mud or grains. Only classes used in the geology of the Fort Payne Formation website are shown.
Dysoxic - Conditions in which there is some oxygen restriction.
Euxinic - Conditions in which there is no oxygen and where this occurs on the seafloor, no life on the sea floor.
Fenestrate bryozoans - Bryozoans in the order Fenestrata, which have mesh- or lace-like structures.
Flexible crinoids - Crinoids (a class of stalked echinoderm) in the subclass Flexibilia, which have flexible cups and tegmens (covering on the top of the crinoid's calyx or crown), with arms usually distinctly differentiated or separated from the cup (calyx).
Flooding surface - Surface across which a rise in base level (sea level) is interpreted. Generally appears as more marine facies overlying a less marine facies with a gap of transitional facies.
Glauconite - A green to blue-green mineral of the micaceous group of minerals, which is commonly associated with deep-water marine deposition under very slow sedimentation rates.
Grainstone - A type of limestone in the Dunham classification, consisting of carbonate framework grains with virtually no mud; well washed and this grain supported (see Dunham classification).
Highstand Systems Tract (HST) - That part of a depositional sequence in sequence stratigraphy, which is between the maximum flooding surface and the next lowstand surface or sequence boundary. It records deposition at relatively high sea level. For more information see SEPM's glossary of sequence stratigraphy.
Holdfast - The attachment structure for a crinoid; often appears root-like.
Inadunate crinoids - Refers to crinoids (a class of stalked echinoderm) in the subclass Inadunata that have a different arrangement of plates than camerates, This subclass has been eliminated in some classification schemes.
Mass flow - Any of a group of liquefied or fluidized sediment flows including slumps, slides, debris and flows.
Maximum (marine) flooding surface - Surface that marks the deepest water facies in a sequence of rock. It is the boundary between the underlying transgressive systems tract and overlying highstand systems tract. For more information see SEPM's glossary of sequence stratigraphy.
Mud mound - General term for a topographically high, generally semicircular feature composed dominantly of fine-grained particles. In the Fort Payne Formation, mud mounds are buildups of siliclastic and carbonate mud.
Mudstone - A type of limestone in the Dunham classification, consisting entirely of carbonate mud (see Dunham classification). To avoid confusion for the usage of this term in argillaceous (shaly) rocks, the term micstone (after micrite) is sometimes used.
Onlap - A term to describe the geometric relationship between beds, in which younger (overlying) beds pinch out up dip. Downlap, offlap, and onlap were used first to describe large regional relationships on seismic lines, but were then used for geometric relationship descriptions in sequence stratigraphy. For more information see SEPM's glossary of sequence stratigraphy.
Packstone - A type of limestone in the Dunham classification, consisting of grain-supported carbonates with some mud (see Dunham classification).
Parasequence - The smallest subdivision of sequence stratigraphy, referring to a relatively conformable succession of genetically related beds bounded by marine flooding surfaces and their correlative surfaces. Essentially, parasequences define a succession of beds or facies, which were deposited transitionally with each other. For more information see SEPM's glossary of sequence stratigraphy.
Pelmatazoan - A subdivision of echinoderms consisting of sessile forms such as crinoids and paracrinoids.
Photic zone - That part of the sea or ocean in which sufficient sunlight penetrates to allow photosynthesis.
Recumbent fold) - A structurally overturned fold in which the axial plane of the fold is nearly horizontal.
Sequence (in sequence stratigraphy) - Genetically related succession of strata bounded by unconformities or their correlative surfaces.
Sequence stratigraphy - A methodology for organizing successions of strata into natural, hierarchial, genetic packages linked to changes in relative water depth. There are different types or methods of sequence stratigraphy, mostly differing in which types of correlative or bounding surfaces are used to define the sequences. Greatly facilitates understanding and prediction of depositional facies and lithologies away from a known data point. For more information see SEPM's glossary of sequence stratigraphy.
Siliclastic - Non-carbonate rocks, which tend to be dominated by quartz (silica) grains.
Skeletal shelter cavities - Irregular, primary cavities formed in limestone by draping of planar skeletal debris such as fenestrate bryozoan fronds over other skeletal debris. Commonly filled with yellowish-colored carbonates, silt or cement in the Fort Payne buildups.
Spicule - Tiny (often microscopic), needle-like features that form the skeletal framework of sponges. In different types of sponges they may be composed of silica or calcium.
Stromatactus cavities - Irregular networks, generally less than 4 inches (10 cm) in length, that may or may not be cement filled, tend to have flat bottoms and irregular tops, and are characteristic of Waulsortian-type mounds. Their origin has never been fully explained.
Submarine fan - A sedimentary deposit at the bottom or toe of a submarine slope. Fans generally form at the base of submarine channels at the base of slopes or ramps. They are thick at their source and then thin in broad, semi-circular to lobate geometries away from the source.
Taphonomy - Study of the processes that operate after the death of an organism. When identified, these provide insights to the environment of deposition, rates of sedimentation, and more. A subdivision of paleoecology.
Time-rich bed - A thin unit deposited through a long time interval such as the New Providence Member of the Fort Payne Formation (17.5 Ma, Leslie et al., 1996). Likely to have bioturbation, bottom oxygen permitting. Also a condensed section or condensed bed, in that a significant amount of time is represented by the bed.
Transgressive Systems Tract (TST) - In sequence stratigraphy, that part of a depositional sequence between the lowest marine flooding surface and the maximum marine flooding surface. Records deposition during relatively rising sea level. For more information see SEPM's glossary of sequence stratigraphy.
Turbidity current - A type of sediment-gravity flow in which sediment-laden water flows downslope as a current because it has higher density than the surrounding water. These are common on marine slopes.
Turbidite - The deposit of a turbidity current. Turbidites exhibit a common succession of bedding and grain distribution called a Bouma sequence, which is related to the physical parameters of deposition from a turbidity current.
Wackestone - A type of limestone in the Dunham classification, consisting of carbonates with ten percent or more grains, but grains are mud-, rather than grain-supported (see Dunham classification).
Waulsortian mound - Name given to fine-grained (micritic) carbonate mud mounds first recognized near Waulsort, Belgium. Typical of the Lower Carboniferous (Lower to Middle Mississippian Period) worldwide, commonly associated with crinoidal debris and contain voids often filled with sparry calcite (stromatactis structures).
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