Kubizwa ngokuthi i-glaciation iminyaka yeqhwa, inkathi yeqhwa noma inkathi yeqhwa lezi zikhathi zokuma kwezwe zenzeka phakathi nokupholisa okukhulu kwesimo sezulu somhlaba, okuholela emakhazeni amanzi, ukwanda kwezingqimba zeqhwa ezitholakala ezindaweni ezishisayo kanye nokuvela kweqhwa lezwekazi. Ngalezi zikhathi izitshalo nezilwane kufanele zivumelane nezimo ezintsha.
Kulesi sihloko sizokutshela ukuthi yiziphi izikhathi zeqhwa eziyinhloko, yiziphi izici zabo, izimbangela kanye nemiphumela.
ziyini izinkathi zeqhwa
Kuyizinkathi zobude besikhathi esiguquguqukayo (imvamisa eside: amashumi ezigidi zeminyaka) lapho ukuphila kufanele kujwayelane nesimo sezulu esomile nesibandayo noma kubhubhe. Bangakwazi ukuguqula ngokuphawulekayo ukuma kwezwe, imvelo kanye nesimo sezulu seplanethi.
Izikhathi zeqhwa zingahlukaniswa zibe yizinkathi zeqhwa, izinkathi zokubanda ezikhulayo, nezinkathi zokuhlangana kweqhwa, izikhathi zokuncipha kwamakhaza, nezinga lokushisa elikhuphukayo, nakuba lisengaphakathi kwemingcele enengqondo yokupholisa isikhathi eside koMhlaba.
Umhlaba uye waba namaqhwa amaningi ngezikhathi ezithile, owokugcina owaqala eminyakeni eyi-110.000 edlule. Kulinganiselwa ukuthi yonke impucuko yethu yathuthuka futhi yaphila phakathi nenkathi yeqhwa eyaqala eminyakeni eyi-10.000 edlule.
umlando we-ice age
I-Quaternary Ice Age yenzeka ngesikhathi se-Cenozoic Neogene. Nakuba okwamanje amaphesenti angu-10 kuphela omhlaba embozwe yiqhwa, siyazi ukuthi lokhu akunjalo ngaso sonke isikhathi. Izinguzunga zeqhwa kuwo wonke umlando wokwakheka komhlaba zishiye imikhondo ebonakalayo, ngakho namuhla sazi izikhathi ezinhlanu ezinkulu zeqhwa, okuyizi:
- I-Huron Ice Age. Yaqala eminyakeni eyizigidi eziyizinkulungwane ezingu-2.400 edlule futhi yaphela enkathini ye-Paleoproterozoic geological eminyakeni eyizigidi eziyizinkulungwane ezingu-2.100 edlule.
- I-Sturtian-Varangian glaciation. Ithola igama layo kusukela esikhathini se-low-temperature Neoproterozoic, eyaqala eminyakeni eyizigidi ezingu-850 edlule futhi yaphela eminyakeni eyizigidi ezingu-635 edlule.
- I-Andean-Saharan Glacier. Kwenzeka phakathi kweminyaka eyizigidi ezingu-450 kanye ne-420 edlule, ku-Paleozoic (Ordovician kanye ne-Silurian), futhi yiyona emfushane eyaziwayo.
- I-Karoo Glacier. Yaqala eminyakeni eyizigidi ezingu-360 edlule futhi yaphela eminyakeni eyizigidi ezingu-100 kamuva, kuPaleozoic efanayo (iCarboniferous nePermian).
- I-quaternary glaciation. Eyakamuva kakhulu, eyaqala eminyakeni eyizigidi ezingu-2,58 edlule esikhathini se-Neogene senkathi ye-Cenozoic, izophela manje.
Umhlaba wawuyibhola leqhwa
Inkathi yeqhwa yomhlaba wonke, i-superglacial noma "ibhola leqhwa" loMhlaba kuwumbono wokuthi kwenzekani ngesikhathi se-Neoproterozoic wamazinga okushisa aphansi, lapho iqhwa elilodwa noma ngaphezulu bekungakhiqizwa emhlabeni wonke, limboze uMhlaba wonke ngongqimba oluminyene lweqhwa, futhi lehlise izinga lokushisa elijwayelekile libe ngu-50°C.
Kulinganiselwa ukuthi lesi simo (sakhiwe ku-Sturtian-Varangian Ice Age) sathatha iminyaka engaba yizigidi eziyizinkulungwane eziyi-10, isikhathi seqhwa esikhulu kunazo zonke emlandweni womhlaba, futhi siholele ekuqothulweni cishe okuphelele kokuphila. Nokho, ubuqiniso bayo kuyindaba eyimpikiswano emphakathini wesayensi.
Iminyaka emincane yeqhwa
Igama libhekise ku inkathi yokubanda okukhulu okwenzeka eMhlabeni kusukela ngekhulu le-XNUMX kuya maphakathi nekhulu le-XNUMX. Isikhathi esishisayo kakhulu esaziwa ngokuthi isimo sezulu esihle kakhulu seNkathi Ephakathi (ikhulu le-XNUMX kuya kwele-XNUMX) saphela.
Akuyona i-glaciation ncamashi, kude nayo, futhi ngokukhuluma ngokwezwe, inokuphila okufushane kakhulu. Kunoma yikuphi, ihlukaniswe yaba izigaba ezintathu, ephawulwe ukwehla kwezinga lokushisa eliphansi kakhulu: 1650, 1770 no-1850.
imiphumela yeminyaka yeqhwa
I-glaciation idala uhlobo olukhethekile lokuguguleka kwedwala. Imithelela emikhulu ye-Ice Age ingahlukaniswa izigaba ezintathu:
- I-Geology. Iqhwa lakha uhlobo olukhethekile lokuguguleka emadwaleni, kungaba ngokupholisa, ngokucindezelwa yiqhwa noma isimo sezulu, okwenza isimo sezwe esiqondile kakhulu emadwaleni esikhathi sawo.
- Amakhemikhali. Ama-ice cores avelayo akhona njengeqhwa elingapheli ezimweni eziningi (njengaphezu kwezintaba eziningi ezinde) ngenxa yezinguquko ze-isotopic emanzini, okuwenza abe yisisindo esindayo kunokujwayelekile. Lokhu kubangela ukuhwamuka okuphezulu kanye nezinga lokushisa elincibilikayo lamanzi.
- I-Paleontology. Lezi zinguquko ezinkulu ezingeni lokushisa nesimo sezulu ngokuvamile zihambisana nokushabalala okukhulu, okukhiqiza isamba esikhulu sezinto eziphilayo, kukhiqizwe amadiphozithi amakhulu, futhi kushiye ubufakazi obuningi bezinsalela. Ngaphezu kwalokho, izilwane ezingakwazi ukuzivumelanisa namakhaza zibalekela ezindaweni ezishisayo, zenza izindawo zokukhosela ezinoqhwa kanye nokunyakaza okukhulu kwe-biogeographical.
Izimbangela zeminyaka yeqhwa
Izimbangela zeminyaka yeqhwa zingahlukahluka futhi zibe nempikiswano. Ezinye izinkolelo-mbono ziphakamisa ukuthi zibangelwa izinguquko ekubunjweni komkhathi okunciphisa ukufakwa kwamandla okushisa avela elangeni, noma izinguquko ezincane kumjikelezo woMhlaba.
Ngakolunye uhlangothi, Kungase kube ngenxa yokunyakaza kwamapuleti e-tectonic: uma amazwekazi esondelana, evala isikhala olwandle, ingaphakathi layo liyoma futhi lifudumale, kunciphisa imingcele yokuhwamuka. Nokho, ukube amazwekazi ebengase ahlukane futhi ahlukane, bekungaba namanzi amaningi okupholisa nokugcina amazinga okushisa embulunga yonke azinzile.
izilwane ze-ice age
Izilwane ezisinde ekushintsheni kwe-Ice Age futhi zajwayela ukuphila ezindaweni eziwugwadule eziqandisiwe zazivame ukuba nezici eziqondile: izingqimba eziwugqinsi zoboya namafutha ezazivikela imizimba yazo emakhazeni angaphakathi, ukujwayela ukwakheka kwe-metabolic emakhazeni nesomiso, kanye nokudla okunekhalori ephezulu. .
Kodwa-ke, ngokubheka izinhlobo zezilwane eziyinhloko zenkathi yokugcina yeqhwa, kungenzeka ukuqonda izindlela eziqondile uhlobo ngalunye olusabela ngayo emakhazeni, njenge:
- Umammoth woboya. Izindlovu ezinenhlanhla ziye zajwayelana namakhaza, futhi imizimba yazo imbozwe yizingqimba zoboya obufinyelela kumitha ubude, futhi amazinyo azo angakwazi ukuchoboza igobolondo eliqinile lezitshalo eziqandisiwe. Baphila iminyaka engaba ngu-80.
- Ingwe enamazinyo amaSaber. Lezi zilwane ezidla ezinye ezinamandla zazimfushane, zisinda futhi zijiyile kunamabhubesi, zinamazinyo angamasentimitha angu-18 ubude ayekwazi ukuvula imihlathi yawo ngama-degree angu-120 lapho ziluma, konke ukuze zihlale zisebenza kahle emathafeni okuzingela ngaleso sikhathi.
- obhejane abanoboya. Abanduleli bobhejane banamuhla, imizimba yabo emikhulu yayimbozwe ngoboya futhi inesisindo esingamathani angu-4. Izimpondo nogebhezi lwalo kwakunamandla futhi bukhulu, futhi lalikwazi ukumba eqhweni lifuna ukudla.
Ngithemba ukuthi ngalolu lwazi ungafunda kabanzi mayelana neminyaka yeqhwa ehlukene kanye nezici zabo.