Bruce Levell on Bias in the Sedimentary Record 

Glossary

ammonites - extinct marine molluscs

aragonite – a form (polymorph)of calcium carbonate formed by certain marine organisms and distinct from calcite, which is another calcium carbonate polymorph.

bedding plane - a surface representing a contact between a deposit and the depositing medium when the depositional environment or sediment supply changes

Blue Lias - a late Triassic and early Jurassic fossil-rich limestone and shale formation in southern, eastern and western England and parts of South Wales

calcareous (structures) - organisms which are primarily made of calcium carbonate, e.g, snails

Cryogenian glaciations – the two “Snowball Earth” glaciations which occurred during the Cryogenian period in the Neoproterozoic

echinoid spines - sea urchin spines

foraminifera - single-celled marine organisms

glacial lacustrine deposits – lake deposits from a glacier

intermediate forms (in evolution) - evidence of organisms showing transitional features that give evidence of evolutionary change over time

Milankovitch band - an interval of frequencies corresponding to a Milankovitch cycle

Milankovitch cycles - collective periodic effects of changes in the Earth's movements on its climate over long timescales

"Mind the gap" - common UK warning phrase issued to rail passengers to take caution when crossing over the gap between the train doorway and the station platform edge

paleontological data (for chronology) - dating through the fossil record

periglacial - relating to or denoting an area adjacent to a glacier or ice sheet or otherwise subject to repeated freezing and thawing

(in) spate (of a river) - containing a lot more water than usual and flowing rapidly

signal shredding – the effect of events subsequent to a deposition of a layer that scrambles the record of the deposition

strand plain - broad belt of sand along a shoreline or river bank

Sturtian Sequence – rocks deposited during the earlier of two postulated “Snowball Earth” worldwide glaciations during the Cryogenian Period

taphonomy - the study of how biological remains are decomposed, buried, and preserved

unconformity - a discontinuity in rock sequence indicating interruption of sedimentation