Surf Wiki
Save to docs
general/landforms

From Surf Wiki (app.surf) — the open knowledge base

Reef knoll

Accumulated calcareous material on an ancient seabed

Reef knoll

Accumulated calcareous material on an ancient seabed

A reef knoll is a landform that comprises an immense pile of calcareous material that had previously accumulated on an ancient sea floor. Reef knolls are geological remnants of reefs and other organic concentrations of calcareous organisms. Reef knolls are often fossil-rich, with prehistoric corals, sponges, calcareous algae, and other reef-builders contributing to a large portion of the structure's volume. This density of skeletal material allows the structure to withstand sea currents and stand freely.

Reef knolls can be divided into bioherms and biostromes. A bioherm is a landform of organic sedimentary rock enclosed or surrounded by rock of different origin. A biostrome is a distinctly bedded or broadly lenticular sedimentary rock landform. Krumbein additionally used these terms to distinguish different shapes of stromatolites: "Distinctly bedded, widely extensive, blanketlike build-ups are biostromes. Nodular, biscuit-like, dome-shaped or columnar stromatolites are also referred to as bioherms".

England

Thorpe Kail, Stebden and Elbolton hills, against Thorpe Fell, from north east, near Hebden

Examples on the Derbyshire/Staffordshire border include Thorpe Cloud and Bunster Hill in southern Dovedale, and also Chrome Hill and Parkhouse Hill at the northern end.

These structures are often most clearly seen where the surrounding rocks are much softer and so can be preferentially eroded. All the Derbyshire examples quoted lie at the edge of the limestone areas; Chrome and Parkhouse lie at the divide between limestone and the much softer shale.

Examples in the Yorkshire Dales lie on the downthrow side (north) of the Mid Craven Fault. There is one set located around Thorpe (Skelterton, Butter Haw, Stebden, Elbolton, Thorpe Kail, Myra Bank and Hartlington Kail); one set located around Malham (Burns Hill, Cawden, and Wedber); and a set around Settle (High Hill and Scaleber).

It was once proposed that in Lancashire, reef knolls could be seen between the villages of Worston and Downham near Clitheroe.

References

References

  1. Cope, F. Wolverson (1976) ''Geology Explained in the Peak District'', David & Charles
  2. "Definition of BIOHERM".
  3. "Definition of BIOSTROME".
  4. Krumbein, W.E., Brehm, U., Gerdes, G., Gorbushina, A.A., Levit, G. and Palinska, K.A.. (2003). "Fossil and Recent Biofilms: A Natural History of Life on Earth". Kluwer Academic.
  5. Ramsbottom, W.H.C.. (1974). "The Geology and Mineral Resources of Yorkshire". Yorkshire Geological Society.
  6. "English Nature: Lancashire Geology".
  7. (1972). "Origin and structure of Lower Viséan "reef"limestones near Clitheroe, Lancashire". Proceedings of the Yorkshire Geological Society.
  8. "Clitheroe Reef Belt". Craven & Pendle Geological Society.
Info: Wikipedia Source

This article was imported from Wikipedia and is available under the Creative Commons Attribution-ShareAlike 4.0 License. Content has been adapted to SurfDoc format. Original contributors can be found on the article history page.

landforms
Want to explore this topic further?

Ask Mako anything about Reef knoll — get instant answers, deeper analysis, and related topics.

Research with Mako

Free with your Surf account

Content sourced from Wikipedia, available under CC BY-SA 4.0.

This content may have been generated or modified by AI. CloudSurf Software LLC is not responsible for the accuracy, completeness, or reliability of AI-generated content. Always verify important information from primary sources.

Report