Kogin Turkana

Babban tafkin Turkana a Gabashin Afirka (musamman arewa maso yammacin Kenya da kudancin Habasha, ƙananan sassan gabashin Uganda da kudu maso gabashin Sudan ta Kudu) ya ƙayyade babban kwandon endorheic, kwandon ruwa ba tare da fitowa ba wanda ke kewaye da tsarin Gregory Rift a arewa maso kudu a Kenya da kudanci Habasha. Matsayi mafi zurfi na kwandon shine Tafkin Turkana, Tafkin soda mai laushi tare da babban aikin muhalli a cikin Gregory Rift.

Wani karamin ma'anar kalmar Turkana Basin yana kuma amfani da shi sosai kuma yana nufin Tafkin Turkana da mahallinta a cikin iyakar Gregory Rift a Kenya da Habasha. Wannan ya hada da kwarin Kogin Omo a Habasha. Basin a cikin ƙarancin ma'anar shi ne shafin yanar gizon geological wanda ke dauke da ɗayan mafi ci gaba da sarrafa burbushin burbushin Plio-Pleistocene  tare da wasu burbushin da suka tsufa kamar Cretaceous.  Daga cikin mahimman wuraren burbushin burbushin halittu na Basin sune Lothagam, Allia Bay, da Koobi Fora.

 Yanayin ƙasa 
Tafkin Turkana yana zaune a tsakiyar Turkana Basin kuma yana kewaye da hamadar Chalbi a gabas, filayen Lotakipi a arewa, Karasuk a yamma da Samburu a kudu. An haɗa su a cikin waɗannan yankuna da tsire-tsire na hamada, ciyawa na hamada da shrubland, da kuma warwatse Akasia ko wuraren ciyawa. Kogin Omo ne kawai na gaskiya a Habasha, a arewacin kwandon, wanda ke fitowa cikin tafkin a gefen arewacinsa kuma yana ba da tafkin sama da kashi 98% na ruwan da ke shigowa a shekara-shekara. Koguna biyu masu saurin wucewa - wanda kusan shi kaɗai ke ba da gudummawa ga sauran kashi 2% na shigar ruwa - sune Kogin Turkwel da Kogin Kerio a Kenya, a yammacin ɓangaren kwandon.  Yawancin Turkana Basin a yau ana iya bayyana su a matsayin busasshiyar daji ko ma hamada. Banda kwarin Omo- zuwa arewa.

Manyan garuruwa a cikin Turkana Basin sun hada da Lokitaung, Kakuma, Lodwar, Lorogumu, Ileret da Kargi . Mutanen Turkana suna zaune a yammacin Basin, mutanen Samburu da Pokot suna zaune a kudu, kuma mutanen Nyangatom, Daasanach da Borana Oromo suna zaune a arewa da gabas.

 Yanayin ƙasa 
Tsohon rikodin sedimentary sun koma zuwa Cretaceous, gami da raka'a da aka ambata a baya a matsayin Turkana grits kamar Lapurr Sandstone kuma suna mamayewa da jerin kogin masu gudana zuwa gabas da ke gudana cikin Tekun Indiya;  daga baya daga Oligocene da Miocene suna nuna irin wannan tsarin ruwa wanda duk da haka ba a haɗa su a ƙarƙashin rukuni ɗaya ko tsarin ƙasa ba Kimanin shekaru miliyan 4.2 da suka gabata (Ma), yankin ya sami yaduwa da kuma muhimmiyar dutsen wuta, wanda ke da alaƙa da Gombe basalts a cikin Koobi Fora formation zuwa gabas da kuma Lothagam basalts zuwa kudu; wannan taron ya haifar da tafki a tsakiyar kwandon kuma a bayyane ya kafa tsarin zamani, ci gaba na Turkana Basin . 

Kashewa a cikin Turkana Basin gabaɗaya ana motsa shi da farko ta hanyar raguwa, sakamakon raguwa tsakanin faranti na Somaliya da Nubian wanda ya haifar da jerin tsarin horst da graben, kuma ya haifar da kusan kilomita 1 na ajiyar sedimentary a tsakiyar kwandon kowane shekaru miliyan 1.  Rubuce-rubucen sedimentary, waɗanda suka zama mafi ƙanƙanta da raguwa a nesa da tsakiyar kwandon, sun nuna cewa kwandon ya sauya tsakanin tsarin ruwa da na tafki a duk lokacin Plio-Pleistocene, da farko sakamakon ci gaba da aikin dutsen wuta da farko zuwa gabas, kuma daga baya zuwa kudancin kwandon.

 Tarihin juyin halitta 
Rubuce-rubucen burbushin halittu a cikin kwandon sun taimaka wajen kafa yawancin abin da aka sani game da juyin halittar fauna na Afirka a cikin Neogene da Quaternary .  Kamar yadda yake a wasu yankuna, rikicin ɓarkewar ƙazanta na Miocene na ƙarshen-Miocene da yanayin sanyi na duniya da alama sun yi tasiri a kan ƙungiyoyin burbushin halittu a cikin Basin Turkana, ko dai ta hanyar ƙaura ko kuma abubuwan juyin halitta na de novo .  Fossilized ganyen dabi'un mafi kyawun shimfidar wurare, abubuwan da suka shafi al'umma, da haɓaka " C4 " ko gudummawar tsire-tsire masu bushewa don shan carbon na herbivore, duk suna nuna cewa duniyar Miocene ta fi Pliocene kyau.  Wasu herbivores, kamar dawakai, sun amsa da sauri ga yaduwar C4 ciyayi, yayin da sauran herbivores sun samo asali da sannu-sannu, ko kuma sun ci gaba da amsa daban-daban ga wani wuri mai bushe. 

Nazarin juyin halitta na Turkana Basin sun gano abin da zai iya zama manyan lokutan juyin halitta bayan Miocene, musamman a ƙarshen Pliocene da farkon Pleistocene,   kodayake binciken da ya biyo baya ya ba da shawarar canje-canje a hankali a cikin abubuwan da ke cikin al'umma masu cin ganyayyaki a duk wannan lokacin.  Ɗaya daga cikin dalilan da ya sa aka mayar da hankali kan marigayi Pliocene da farkon Pleistocene shine manyan wallafe-wallafen akan burbushin hominin da ke nuna "radiation mai daidaitawa" a fadin wannan iyaka. Duk da yake ana ɗaukar nau'ikan hominin da suka gabata a matsayin wani ɓangare na zuriyar "Anagenetic",  burbushin burbushin hominin sun zama daban-daban a Gabashin Afirka shekaru miliyan 2.5 da suka gabata, tare da nau'ikan nau'ikan Australopithecine masu ƙarfi da kakannin ɗan adam na farko da aka samo da farko a cikin Turkana Basin, kuma a ƙarshe a Afirka ta Kudu. Shaidar farko da aka yi amfani da kayan aikin dutse tsakanin kakannin mutane ana samun su a cikin Turkana Basin.

 Bayanan da aka ambata