cyclothem
Jump to navigation
Jump to search
English[edit]
Etymology[edit]
cyclo- + Ancient Greek θέμα (théma, “a deposit”). Coined by American scientists Harold R. Wanless & J. Marvin Weller in 1932.[1]
Noun[edit]
cyclothem (plural cyclothems)
- (geology) A vertical stratigraphic sequence caused by repeated flooding by the sea
Derived terms[edit]
References[edit]
- ^ Harold R., Wanless, Weller, J. Marvin (1932 December 30) “Correlation and Extent of Pennsylvanian Cyclothems”, in Bulletin of the Geological Society of America[1], volume 43, number 4, The Geological Society of America, , page 1003:
- Cyclothem is derived from two Greek words: Cyclos, cycle, and thema, a deposit. It has been proposed that each of the cyclical series of beds in the Pennsylvanian system be considered a formation (Weller, Jour. Geol., vol. 38, 1930, p. 101). Inasmuch as the word "formation" is very loosely employed in stratigraphy to designate a single bed, a group of beds having some character in common such as age, composition, or origin, a group of more or less unrelated beds combined for convenience into a carto-graphical unit, etc., this term seems inappropriate for the very definite subdivisions of the Pennsylvanian system that are coming to be widely recognized, unless it be always prefixed by the adjective "cyclical." The word "cyclothem" is therefore proposed to designate a series of beds deposited during a single sedimentary cycle of the type that prevailed during the Pennsylvanian period.