Kubizwa ngokuba ngumkhenkce iminyaka yomkhenkce, ixesha lomkhenkce okanye ixesha lomkhenkce la maxesha okwakheka komhlaba ayenzeka ngexesha lokuphola okukhulu kwemozulu yomhlaba, nto leyo ekhokelela ekukhenkceni kwamanzi, ukwandiswa kweebhloko zomkhenkce ezimhlophe kunye nokubonakala komkhenkce welizwekazi. Ngala maxesha, izityalo nezilwanyana kufuneka ziqhelane nemekobume entsha.
Kweli nqaku siza kukuxelela ukuba yeyiphi iminyaka ephambili yomkhenkce, zeziphi iimpawu zabo, izizathu kunye nemiphumo.
yintoni iminyaka yomkhenkce
Ngamaxesha obude obuguquguqukayo (ubude obuqhelekileyo: amashumi ezigidi zeminyaka) apho ubomi kufuneka buqhelane nemozulu eyomileyo nebandayo okanye butshabalale. Banokuguqula ngokuphawulekayo ubume bejografi, bebhayoloji kunye nemozulu yeplanethi.
Iminyaka yomkhenkce inokwahlulwa ibe ngamathuba omkhenkce, amaxesha okubanda okunyukayo, kunye namaxesha okuhlangana komkhenkce, amaxesha okuhla kwengqele, kunye nokwanda kwamaqondo obushushu, nangona kungaphakathi kwemida esengqiqweni yokuphola kwexesha elide loMhlaba.
Umhlaba uye wafumana imikhenkce emininzi ngamaxesha, eyokugqibela eyaqala kwiminyaka eyi-110.000 eyadlulayo. Kuqikelelwa ukuba yonke impucuko yethu yaphuhla kwaye yaphila ngexesha lokuhlangana komkhenkce elaqala kwiminyaka eyi-10.000 eyadlulayo.
imbali ice age
I-Quaternary Ice Age yenzeke ngexesha le-Cenozoic Neogene. Nangona okwangoku kuphela i-10% yomhlaba ogqunywe ngumkhenkce, siyazi ukuba oku akusoloko kunjalo. Umkhenkce kuyo yonke imbali yejoloji yoMhlaba ushiye umkhondo obonakalayo, ke namhlanje siyawazi amaxesha amahlanu amakhulu womkhenkce, athi:
- Huron Ice Age. Yaqala kwiminyaka eyi-2.400 yeebhiliyoni eyadlulayo kwaye yaphela kwi-Paleoproterozoic geological era 2.100 billion kwiminyaka eyadlulayo.
- Umkhenkce weSturtian-Varangian. Ifumana igama layo kwixesha lobushushu obuphantsi lwe-Neoproterozoic, eyaqala kwi-850 yezigidi zeminyaka eyadlulayo kwaye yaphela kwi-635 yezigidi zeminyaka eyadlulayo.
- I-Andean-Saharan Glacier. Yenzeka phakathi kwe-450 kunye ne-420 yezigidi zeminyaka eyadlulayo, kwi-Paleozoic (i-Ordovician kunye ne-Silurian), kwaye yeyona imfutshane eyaziwayo.
- Umkhenkce waseKaroo. Yaqala kwizigidi ezingama-360 kwiminyaka eyadlulayo kwaye yaphela kwi-100 lezigidi zeminyaka kamva, kwiPaleozoic efanayo (iCarboniferous kunye nePermian).
- I-quaternary glaciation. Olona lwakutsha nje, olwaqala kwi-2,58 yezigidi zeminyaka eyadlulayo kwixesha le-Neogene lexesha le-Cenozoic, liya kuphela ngoku.
Umhlaba wawuyibhola yekhephu
Ixesha lomkhenkce wehlabathi, i-superglacial okanye "snowball" yoMhlaba luqikelelo malunga nento eyenzekayo ngexesha leNeoproterozoic amaqondo obushushu aphantsi, ngexesha elinye okanye ngaphezulu komkhenkce bekuya kuveliswa kwihlabathi jikelele, ukugquma uMhlaba wonke ngongqimba womkhenkce oshinyeneyo, kwaye wehlise ubushushu obuphakathi ukuya kuma -50°C.
Kuqikelelwa ukuba le nto (eyayilwe kwi-Sturtian-Varangian Ice Age) yahlala malunga ne-10 yezigidigidi zeminyaka, elona xesha likhulu lomkhenkce kwimbali yoMhlaba, kwaye likhokelele ekuphelisweni kobomi phantse ngokupheleleyo. Noko ke, ubunyaniso bayo ngumbandela ophikisanayo kwibutho lezenzululwazi.
Iminyaka emincinci yomkhenkce
Igama libhekisa ku ixesha lengqele eqhaqhazelisa amazinyo eyenzeka eMhlabeni ukusuka kwi-XNUMX ukuya phakathi kwenkulungwane ye-XNUMX. Ixesha elishushu ngokukhethekileyo elaziwa njengeyona mozulu ilungileyo yamaXesha Aphakathi (inkulungwane ye-XNUMX ukuya kweye-XNUMX) yaphela.
Ayingomkhenkce ncam, kude kuyo, kwaye xa sithetha ngokwejoloji, inobomi obufutshane kakhulu. Kwimeko nayiphi na into, ihlulwe ibe yizigaba ezithathu, eziphawulwe ngokuhla kweqondo lokushisa eliphantsi: 1650, 1770 kunye ne-1850.
iziphumo zeminyaka yomkhenkce
I-glaciation idala uhlobo olukhethekileyo lokukhukuliseka eweni. Iimpembelelo eziphambili ze-Ice Age zinokwahlulwa ngokweendidi ezintathu:
- Ijoloji. Umkhenkce wadala uhlobo olukhethekileyo lokhukuliseko ematyeni, mhlawumbi ngokupholisa, ngoxinzelelo lomkhenkce okanye ngenxa yemozulu, ukudala umhlaba ocacileyo kakhulu ematyeni exesha lawo.
- Iikhemikhali. Iziphumo ze-ice cores zikhona njengekhephu elisisigxina kwiimeko ezininzi (ezifana naphezu kweentaba ezininzi ezinde) ngenxa yokutshintsha kwe-isotopic emanzini, okwenza ubunzima obunzima kunesiqhelo. Oku kubangela ukuba amanzi abe ngumphunga kunye nokunyibilika kobushushu bamanzi.
- Paleontology. Olu tshintsho lukhulu kubushushu nakwimozulu ludla ngokukhatshwa kukutshabalala kwabantu abaninzi, nto leyo evelisa izixa ezikhulu zezinto eziphilayo, idipozithi enkulu, ize ishiye ngasemva intaphane yobungqina befosili. Ngaphezu koko, izilwanyana ezingakwaziyo ukuziqhelanisa nokubanda zibalekela kwiindawo ezishushu, zenza iindawo zokuhlala ezinomkhenkce kunye neentshukumo ezinkulu zebiogeographical.
Iimbangela zeminyaka yomkhenkce
Izizathu zeminyaka yomkhenkce zinokuhluka kwaye ziphikisana. Ezinye iithiyori zicebisa ukuba zibangelwa utshintsho ekubunjweni kwe-atmosphere enciphisa igalelo lamandla ashushu ukusuka elangeni, okanye utshintsho oluncinci kwi-orbit yomhlaba.
Ngakolunye uhlangothi, Isenokuba ngenxa yentshukumo yeepleyiti zetectonic: ukuba amazwekazi asondelelana, avale indawo elwandle, ingaphakathi layo liba lome kwaye lifudumale, linciphisa imida yokuphuma komphunga. Noko ke, ukuba amazwekazi ebenokusasazeka aze ahlukane, bekuya kubakho amanzi amaninzi okupholisa nokugcina ubushushu behlabathi buzinzile.
izilwanyana ice age
Izilwanyana eziye zasinda kutshintsho lwe-Ice Age zaza zaqhelana nobomi kwiindawo ezinendawo engumkhenkce ezihlala zineempawu ezikhethekileyo: iileya ezishinyeneyo zoboya namafutha ezazikhusela imizimba yazo kubanda ngaphakathi, ukuziqhelanisa nengqele nembalela, kunye nokutya okunekhalori ephezulu. .
Nangona kunjalo, ngokujonga kwiintlobo zezilwanyana eziphambili zexesha lokugqibela lomkhenkce, kunokwenzeka ukuqonda iindlela ezithile uhlobo ngalunye olusabela ngayo kubanda, njengale:
- Imammoth yoboya. Iindlovu ezinethamsanqa ziye zaqhelana nengqele, kwaye imizimba yazo yogqunywe ngoboya obufikelela kwimitha ubude, kwaye amazinyo azo anokutyumza iqokobhe eliqinileyo lohlaza olungumkhenkce. Baphila iminyaka engama-80.
- Ingwe eneesaber. La marhamncwa anamandla ayemafutshane, enzima kwaye engqindilili kuneengonyama, enamabamba anobude obuziisentimitha ezili-18 awayekwazi ukuvula imihlathi yawo kangange-120 degrees xa eluma, konke oko ukuze ahlale esebenza kuloo mathafa awayenomkhenkce okuzingela ngelo xesha.
- imikhombe enoboya. Abanduleli bemikhombe yanamhlanje, imizimba yabo emikhulu yayigqunywe ngoboya kwaye inobunzima obufikelela kwiitoni ezi-4. Iimpondo zayo nokakayi zayo zazisomelela yaye zinkulu ngakumbi, yaye yayikwazi ukugqobhoza ekhephini ifuna ukutya.
Ndiyathemba ukuba ngolu lwazi unokufunda ngakumbi malunga nobudala bomkhenkce obuhlukeneyo kunye neempawu zabo.