Jerin lokaci na ƙanƙara

Jerin lokaci na ƙanƙara
timeline (en) da Wikimedia timeline (en)
Bayanai
Muhimmin darasi	glacial period (en)

Tarihin yanayi a cikin shekaru miliyan 500 da suka gabata, tare da manyan shekarun kankara guda uku da aka nuna, Andean-Sahara (450 Ma), Karoo (300 Ma) da Late Cenozoic. An nuna lokacin sanyi ko zamanin kankara a lokacin Jurassic-Cretaceous (150 Ma).

Akwai manyan shekarun kankara biyar ko shida a tarihin Duniya a cikin shekaru biliyan 3 da suka gabata. Late Cenozoic Ice Age ya fara shekaru miliyan 34 da suka gabata, sabon matakin sa shine Quaternary glaciation, yana ci gaba tun shekaru miliyan 2.58 da suka gabata.

A cikin shekarun kankara, akwai lokutan yanayi mai tsanani da kuma yanayin yanayi mai sanyi, wanda ake kira lokutan glacial da lokutan interglacial, bi da bi. Duniya a halin yanzu tana cikin irin wannan lokacin interglacial na Quaternary glaciation, tare da Lokacin Glacial na Ƙarshe na Quatternary ya ƙare kusan shekaru 11,700 da suka gabata. An san lokacin interglacial na yanzu a matsayin zamanin Holocene . Dangane da Bayanan yanayi, masana kimiyyar yanayi suna nazarin Jihohin yanayi daban-daban da suka samo asali daga glaciation.

Shekaru na kankara da aka sani

Sunan zamanin kankara	Shekaru BP (Ma)	Lokacin yanayin ƙasa	Ya kasance
Pongo	2900–2780		Mesoarchean
Huronian	2400–2100	Siderian Ryacian	Paleoproterozoic
Sturtian Jirgin Ruwa Masu amfani da gas Baykonur	715–680650–635580547	Cryogenian Ediacaran	Neoproterozoic
Andean-Sahara (ciki har da Hirnantian da Late Ordovician glaciation)	450–420	Ƙarshen Ordovician Silurian	Paleozoic
Karoo	360–289	Carboniferous Permian	Paleozoic
Late Cenozoic Ice Age (ciki har da Quaternary glaciation)	34-yanzu	Late PaleogeneNeogene Na huɗu	Cenozoic

Bayani

Samfuri:Life timelineShekarar kankara ta uku, kuma mai yiwuwa mafi tsaNa, an kiyasta ya faru ne daga 720 zuwa 635 Ma (shekaru miliyan) da suka gabata, a cikin Neoproterozoic Era, kuma an ba da shawarar cewa ya samar da na biyu "Snowball Earth", watau lokacin da aka rufe duniya gaba ɗaya da kankara. An kuma ba da shawarar cewa ƙarshen wannan lokacin sanyi na biyu shine ke da alhakin Cambrian_explosion" id="mwjQ" rel="mw:WikiLink" title="Cambrian explosion">Fashewar Cambrian da ta biyo baya, lokacin saurin bambancin rayuwar salula da yawa a lokacin Cambrian Period. Har yanzu ana jayayya da ra'ayin, ko da yake yana samun amincewa tsakanin masu bincike, kamar yadda shaidar da ke cikin ni'imar ta ta hau. 

Ƙananan jerin ƙanƙara sun faru daga 460 zuwa 430 Ma, kuma akwai ƙanƙarar ƙanƙanta mai yawa daga 350 zuwa 289 Ma.  

Late Cenozoic Ice Age ya ga manyan kankara a Antarctica na 34 Ma da suka gabata. A cikin Ma 3 da suka gabata, kankara sun bunkasa a arewacin arewa. Wannan matakin an san shi da Quaternary glaciation, kuma an yi masa alama da yawa ko žasa mai zurfi. Sun fara bayyana tare da mafi girman mita na shekaru 41,000, amma bayan Mid-Pleistocene Transition wanda ya canza zuwa zagaye mai girma, tare da matsakaicin lokacin Shekaru 100,000.  

Nomenclature na Quaternary glacial cycles

Ganin cewa shekaru miliyan 30 na farko na Late Cenozoic Ice Age galibi sun haɗa da Antarctica, Quaternary ya ga kankara da yawa da ke shimfiɗa a sassa na Turai da Arewacin Amurka waɗanda a halin yanzu suna da yawan jama'a kuma suna da sauƙin isa. Saboda haka, masu ilimin ƙasa na farko sun ba da suna a bayyane na lokutan glacial da interglacial na Quaternary Ice Age bayan halaye na yanayin ƙasa, kuma waɗannan sunaye sun bambanta daga yanki zuwa yanki. Rubuce-rubucen ruwa suna adana duk abubuwan da suka gabata; shaidar ƙasa ba ta cika ba saboda abubuwan da suka biyo baya na iya shafe shaidar magabata. Ice cores daga tarin kankara na nahiyar kuma suna ba da cikakken rikodin, amma ba su koma baya a lokacin da bayanan ruwa suka kasance ba. Bayanan Pollen daga tabkuna da bogs da kuma bayanan loess sun ba da mahimman bayanai na alaƙa da ƙasa. Yawancin masu sana'a ne suka kawar da tsarin sunayen. Yanzu ya fi dacewa ga masu bincike su koma ga lokutan ta hanyar lambar isotopic na ruwa. Misali, akwai sauye-sauye biyar na Pleistocene / interglacial da aka rubuta a cikin ruwa a cikin rabin shekaru miliyan da suka gabata, amma kawai an gane sauye-shiryen glacial guda uku a ƙasa a wannan lokacin (Mindel, Riss da Würm).