Nubbin (ƙasa)

A cikin ilimin ƙasa nubbin ƙaramin tudu ne mai laushi wanda ya ƙunshi ainihin dutse wanda ke cike da tubalan da suka rage. Blok din sun samo asali ne daga rushewar dutse da aka rushe. Musamman ana zaton cewa duwatsun nubbins sune raguwa kwarangwal guda ɗaya ko biyu da ke ƙarƙashin ƙasa - kodayake wasu yanayi na iya ci gaba da faruwa da zarar an fallasa duwatsun a saman.

Nubbins suna samuwa a cikin irin wannan hanyar zuwa castle koppies da bornhardts, kuma ana iya ganin siffofin ƙasa guda uku a matsayin maganganu daban-daban na wannan abin mamaki. Nubbins suna faruwa sau da yawa a cikin ƙungiyoyi masu tsari.

Ana iya samun Nubbins a wurare masu zafi da yanayin zafi. A cewar masanin ilimin ƙasa C. R. Twidale wannan shine yanayin da yawancin nubbins ke samuwa. Nubbins a waje da zafi ko yanayi mai zafi sune siffofin ƙasa da aka kafa a cikin zafi da na wurare masu zafi ko kuma a wuraren da ke da zafi sosai. Misalan yankuna tare da nubbins sun haɗa da Kudu maso yammacin Amurka, MacDonnell Ranges a Tsakiyar Ostiraliya da Namaqualand a Kudancin Afirka.

Duk da yake nubbins yawanci an yi su ne da dutse akwai kuma rahotanni na nubbins da aka yi da ignimbrite.

 Duba kuma 

 Grus (geology) - Yankin yashi da raguwar dutse tarawa
 Inselberg - Tsayawa, dutsen dutse mai tsawo a kan fili mai faɗi
 Saprolite - Dutse mai cike da sinadarai

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