Matsayi na asali
 Matsayi na asali |
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A cikin ilimin ƙasa da ilimin ƙasa matakin tushe shine ƙananan iyaka don Matsayi na tsaye na Tsarin rushewa. John Wesley Powell ne ya gabatar da kalmar zamani a cikin shekara ta 1875. [1] William Morris Davis ne ya karɓi kalmar daga baya wanda ya yi amfani da ita a cikin sake zagayowar ka'idar lalacewa.[1][2] "Mataki na ƙarshe" shine farfajiyar da ke haifar da tsinkaye na matakin teku a ƙarƙashin ƙasa (geoid). [1] A wannan matakin tushe ne Yanayin ƙasa ke kusanci saboda rushewa, a ƙarshe yana samar da fili kusa da ƙarshen sake zagayowar rushewa.[3][4]
Har ila yau, akwai ƙananan matakan tushe na tsarin inda duwatsu masu tsayayya ke jinkirta rushewa. wannan sun haɗa da yankunan karst da ke ƙarƙashin dutse marar narkewa. Matakan tushe na iya zama na gida lokacin da manyan wuraren ƙasa ke nesa da teku ko kuma an cire su daga ciki, kamar yadda yake ga wuraren endorheic. Misali na wannan shine rikicin salinity na Messinian, wanda Tekun Bahar Rum ya bushe yana sa matakin tushe ya faɗi fiye da 1000 m a ƙasa da matakin teku..[1][5][6]
Tsawon matakin tushe kuma yana tasiri ga matsayin Deltas da kogin kogin. Tare da zubar da kogi da yaduwar laka matsayi na matakin tushe yana tasiri ga gradient, faɗin da yanayin gado a cikin koguna. Raguwar dangi a matakin tushe na iya haifar da sake daidaitawa a cikin Bayanan kogin ciki har da ƙaurawar knickpoint da watsar da terraces da ke barin su "hanging". An kuma san faɗuwar matakin tushe don haifar da ci gaba da deltas da kuma kogi a tabkuna ko teku.[7] Idan matakin tushe ya faɗi ƙasa da shelf na nahiyar, koguna na iya samar da fili na koguna masu laushi har sai rushewar kai ta shiga cikin ƙasa daga shelfbreak.[7]
Lokacin da matakan tushe suka kasance masu ɗorewa ko koguna masu tasowa na iya kara muni.[7] Matsayi masu tasowa na iya nutsar da ƙananan koguna da ke haifar da Marias. Wannan ya faru a cikin Nilu a lokacin ambaliyar Zanclean lokacin da ƙananan hanyarsa ta zama, a cikin ɗan gajeren lokaci, babban bakin teku wanda ya kai har zuwa kilomita 900 daga cikin ƙasa daga gabar Bahar Rum.[6]
Canjin matakin tushe na iya danganta da dalilai masu zuwa:
- Canjin matakin teku
- Motsi na tectonic[1]
- Kama kogin[1]
- Yaduwar yaduwar ruwa [8]
Manazarta
[gyara sashe | gyara masomin]- ↑ 1.0 1.1 1.2 1.3 1.4 1.5 Cite error: Invalid
<ref>tag; no text was provided for refs namedGoudie2004 - ↑ Orme, Anthony R. (2007). "The Rise and Fall of the Davisian Cycle of Erosion: Prelude, Fugue, Coda, and Sequel". Physical Geography. 28 (6): 474–506. Bibcode:2007PhGeo..28..474O. doi:10.2747/0272-3646.28.6.474. S2CID 128907423.
- ↑ Green, Paul F.; Lidmar-Bergström, Karna; Japsen, Peter; Bonow, Johan M.; Chalmers, James A. (2013). "Stratigraphic landscape analysis, thermochronology and the episodic development of elevated, passive continental margins". Geological Survey of Denmark and Greenland Bulletin. 30: 18. doi:10.34194/geusb.v30.4673.
- ↑ Lidmar-Bergström, Karna; Bonow, Johan M.; Japsen, Peter (2013). "Stratigraphic Landscape Analysis and geomorphological paradigms: Scandinavia as an example of Phanerozoic uplift and subsidence". Global and Planetary Change. 100: 153–171. Bibcode:2013GPC...100..153L. doi:10.1016/j.gloplacha.2012.10.015.
- ↑ Fairbridge, Rhodes W.; Finkl Jr., Charles W. (1980). "Cratonic erosion unconformities and peneplains". The Journal of Geology. 88 (1): 69–86. Bibcode:1980JG.....88...69F. doi:10.1086/628474. S2CID 129231129.
- ↑ 6.0 6.1 Goudie, A.S. (2005). "The drainage of Africa since the Cretaceous". Geomorphology. 67 (3–4): 437–456. Bibcode:2005Geomo..67..437G. doi:10.1016/j.geomorph.2004.11.008. Cite error: Invalid
<ref>tag; name "Goudie2005" defined multiple times with different content - ↑ 7.0 7.1 7.2 Koss, John E.; Ethridge, Frank G.; Schumm, S.A. (1994). "An Experimental Study of the Effects of Base-Level Change on Fluvial, Coastal Plain and Shelf Systems". Journal of Sedimentary Research. 64B (2): 90–98. doi:10.1306/D4267F64-2B26-11D7-8648000102C1865D. Cite error: Invalid
<ref>tag; name "Kossetal1994" defined multiple times with different content - ↑ Babault, Julien; Van Den Driessche, Jean; Bonnet, Stephanie; Castelltort, Sébastien; Crave, Alain (2005). "Origin of the highly elevated Pyrenean peneplain". Tectonics. 24 (2): n/a. Bibcode:2005Tecto..24.2010B. doi:10.1029/2004TC001697.