Relict (geology)
Arelict,ingeology,is a structure or mineral from a parentrockthat did not undergometamorphic changewhen the surrounding rock did, or a rock that survived a destructive geologic process.
Somegeologic processesare destructive or transformative of structures or minerals, and when a process is not complete or does not completely destroy certain features, the left-over feature is a relict of what was there before. For example, relictpermafrostis an area of ancient permafrost which remains despite a change in climate which would prohibit new permafrost from forming[1]or it could be a fragment of ancient soil or sediment found in a youngerstratum.A relictsedimentis an area of ancient sediment which remains unburied despite changes in the surrounding environment. Inpedology,the study ofsoil formationand classification, ancient soil found in the geologic record is called apaleosol,material formed in the distant past on what was then the surface. A relict paleosol is still found on the surface, and yet is known to have been formed under conditions radically different from the present climate and topography.[2]
Inmineralogy,a relict mineral is a surviving mineral from a parent rock that underwent a destructive or transformative process. For example,serpentiniteis a kind of rock formed in a process calledserpentinization,in which a host mineral produces apseudomorph,and the original mineral is eventually replaced and/or destroyed, but is still present until the process is complete.[3]
Withingeomorphologya relict landform is alandformthat took form from geomorphic processes that are not active at present. In aScandinaviancontext, this is often meant to imply that relict landforms were formed before thelast glaciationand survived it under cold-based parts of theice sheet.[4]Climatic geomorphologistJulius Büdelestimated that 95% ofmid-latitudelandforms are relict.[5][6]
See also
[edit]- Hadean zircon– Oldest-surviving crustal material from the Earth's earliest geological time period
References
[edit]- ^Jackson, Julia A. (1980).Glossary of Geology.Falls Church, Virginia:American Geological Institute.pp.529.ISBN978-0-913312-15-5.
- ^Retallack, Gregory J. (2008)."Paleosol".AccessScience.McGraw-Hill Companies.doi:10.1036/1097-8542.484200.
- ^Wicks, Frederick J. (2008)."Serpentinite".AccessScience.McGraw-Hill Companies.doi:10.1036/1097-8542.616300.
- ^Ebert, Karin (2009). "Terminology of long-term geomorphology: a Scandinavian perspective".Progress in Physical Geography.33(2): 163–182.doi:10.1177/0309133309338138.S2CID128915651.
- ^Sarre, R.D. (1993)."Climatic geomorphology".In Kearey, Philip (ed.).The Encyclopedia of the Solid Earth Sciences.Blackwell Science Ltd. pp. 112–114.ISBN978-0-632-03699-8.
- ^Migoń, Piotr(2006). "Büdel, J. 1982: Climatic geomorphology. Princeton: Princeton University Press. (Translation of Klima-geomorphologie, Berlin-Stuttgart: Gebrüder Borntraeger, 1977.)".Progress in Physical Geography.30(1): 99–103.doi:10.1191/0309133306pp473xx.S2CID129512489.