Nhoroondo yekuumbwa kweAmerican Continent
Kondinendi yeAmerica ndeimwe yenyika dzakakura kwazvo pasi rose, inotangira kuNorth Pole kusvika kuSouth Pole. Zvisinei, chimiro chayo chakareba, makomo makuru akadai seAndes neRocky Mountains, uye kuvapo kwezvitsuwa zvikuru seGreenland hazvisi tsaona. Zvese izvi zvinokonzerwa nemaitiro ekugadzira zvinhu akareba—mazana emamiriyoni kusvika kumabhiriyoni emakore—anosanganisira kufamba kweplate ye tectonic, kuputika kwemakomo, kugadzirwa kwegungwa, uye kunyange nguva dzechando. Chinyorwa chino chinoongorora nhoroondo yekuumbwa kwekondinendi yeAmerica muchidimbu asi zvizere.
1. Nyika Inoshanduka uye Basa rePlate Tectonics
Kuti tinzwisise kuumbwa kweAmerica, tinofanira kunzwisisa musimboti wekutanga we geology yemazuva ano: pamusoro penyika pane mapuratifomu e tectonic anofamba pamusoro pepurasitiki inopisa. Mapuratifomu aya anogona kusimuka kubva kune mumwe nemumwe (akapatsanurwa), kuroverana (akaungana), kana kutsvedza kupfuura mumwe nemumwe (akachinja). Kuburikidza nekudyidzana uku ndiko kunoita kuti makondinendi aumbe, aparadzane, asanganiswezve, uye achinje chimiro.
North America inonyanya kugara pamusoro peNorth American Plate, nepo South America iri pamusoro peSouth America Plate. Kumativi avo ekumadokero, makondinendi ese ari maviri anodyidzana nemaplate egungwa akadai sePacific Plate, Nazca Plate, Cocos Plate, uye mamwe maplate madiki. Kudyidzana uku kwakaoma ndiko kunokosha pakuumbwa kwemakomo nemiganhu yemakondinendi.
2. Kutanga: Kuumbwa kweNzvimbo Yekare yeKondinendi
Nhoroondo yemakondinendi inotanga nekuumbwa kwematombo ekare anoumba "pakati" pemakondinendi, anozivikanwa semacraton. MuNorth America, craton hombe, inonzi Canadian Shield, inoumbwa nematombo ekare kwazvo, ane makore anopfuura mabhiriyoni maviri nehafu. Iyi ndiyo yaive hwaro hwekutanga hwakagadzikana hwakabva kuNorth America "yakakura" kuburikidza nekuwedzera zvinhu kuburikidza nemaitiro etectonic.
MuSouth America, chikamu chepakati chekondinendi chakarewo, semuenzaniso muGuiana Shield neBrazilian Shield. Matunhu maviri aya ane matombo ekare anoumba chimiro chikuru cheSouth America.
Ma craton aya akafanana ne "skeleton" yemakondinendi: haachinje zvakanyanya semiganho yemakondinendi inoshanda zvakanyanya. Asi anoshanda senzvimbo dzekuwedzera nyika itsva nekufamba kwenguva.
3. Supercontinent Era: Kubva kuRodinia kuenda kuPangea
Munhoroondo yePasi rese, makondinendi akaungana kuita makondinendi makuru kakawanda. Rimwe remakondinendi makuru ekare raive Rodinia (makore angangoita bhiriyoni imwe apfuura). Munguva iyi, zvikamu zvaizova maAmerica zvaive zvakasiyana zvikuru nezvazviri nhasi. Rodinia payakapatsanuka, zvidimbu zvekondinendi zvakafamba, zvikaumba makungwa matsva, ndokuzobatanidzwazve kuita rimwe kondinendi guru.
Nzvimbo yepamusoro-soro ye "kubatana" kwekondinendi yaive Pangaea, iyo yakavambwa makore angangoita mamiriyoni mazana matatu nemakumi matatu nemashanu apfuura uye yakatanga kupatsanuka makore angangoita mamiriyoni mazana maviri apfuura. Mukati mePangaea, matunhu aizozova North neSouth America akabatana neAfrica neEurope muchikamu chimwe chete chenyika hombe. Kuparara kwePangaea kwaive danho rakakosha mukuumba remangwana reAmerica dzanhasi.
4. Kuparara kwePangaea uye Kuberekwa kweAtlantic Ocean
Pangaea payakatanga kupatsanuka, makondinendi makuru akapatsanuka kuita mapoka maviri makuru: Laurasia kuchamhembe (ramangwana reNorth America, Europe, neAsia) uye Gondwana kuchamhembe (ramangwana reSouth America, Africa, Antarctica, Australia, neIndia).
Nekufamba kwenguva, mukaha wakaparadzanisa America neAfrica neEurope wakawedzera, zvichiumba Atlantic Ocean. Izvi zvakaitika kuburikidza nekupararira kwepasi pegungwa paMid-Atlantic Ridge. Magma yakasimuka, yakabatana kuita goko idzva regungwa, uye zvishoma nezvishoma yakaparadzanisa makondinendi. Nanhasi, Atlantic ichiri kukura nemasendimita akati wandei pagore.
Kuparadzana uku kwaikosha: dai pasina kuvhurwa kweAtlantic, America ingadai isina kuva "nyika pachayo" sezvatinoiziva nhasi.
5. Kuumbwa kweMakomo Makuru eWestern North America
Kudivi rekumadokero kweNorth America, kwakaitika chimwe chinhu chakasiyana. Panzvimbo pekuparadzana, nzvimbo iyi yakasangana nekubonderana kwakawanda uye kuderedzwa kwemaplate egungwa pasi peplate dzemakondinendi. Kwemamiriyoni emakore, plate yegungwa yakakora yakaderedzwa pasi pekondinendi, zvichikonzera magma uye kugadzira makomo anoputika nemakomo.
Imwe nguva huru yekuumbwa kwemakomo yaive orogenesis, iyo yakagadzira zvikamu zveRocky Mountains. Uyezve, nzvimbo huru dzekukanganisa dzakadai seSan Andreas Fault muCalifornia dzakaumbwa nekuchinja kwekuchinja pakati pePacific neNorth American Plates. Nekuda kweizvozvo, mahombekombe ekumadokero eNorth America inzvimbo ine kudengenyeka kwenyika kwakanyanya ine nzvimbo dzakasiyana-siyana.
6. Kuzvarwa kweMakomo eAndes neKushanduka kweSouth America
South America ine chimwe chezvinhu zvinoshamisa zve geology paNyika: Makomo eAndes, makomo marefu kwazvo panyika. MaAndes akaumbwa zvakanyanya nekuderedzwa kweNazca Plate (ndiro yegungwa) pasi peSouth America Plate. Kuderedzwa uku kwakaguma ne:
1. Kusimudzwa kweganda rekondinendi kuti riumbe makomo marefu
2. Kuputika kwakanyanya kwemakomo muAndean band
3. Kudengenyeka kwenyika kwakasimba kunokonzerwa nekukweshana kwemaplate
Maitiro aya anga achienderera mberi kwemakumi emamiriyoni emakore uye achiri kuitika nanhasi. Nekuda kweizvozvo, nyika dzakadai seChile, Peru, neEcuador dziri pa "Pacific Ring of Fire," nzvimbo ine kudengenyeka kwenyika kwakawanda uye kuputika kwemakomo.
7. Kuumbwa kweIsthmus yePanama: Kubatanidza Makondinendi Maviri
Chimwe chezviitiko zvakakosha zve geology munhoroondo yeAmericas kwaive kuumbwa kweIsthmus yePanama makore angangoita mamiriyoni matatu apfuura. Kare, North neSouth America zvainge zvakaparadzaniswa negungwa rinobatanidza Pacific neAtlantic Oceans.
Kukwira kwenzvimbo yePanama kwakakonzerwa nekusanganiswa kwekuputika kwemakomo, kurovera kwemaplate madiki muCaribbean, uye kukwira kwepasi pegungwa. Kukanganiswa kwacho kwaive kwakakura:
– Kubatanidza makondinendi maviri uye kubvumira kutama kwemhuka (Great American Biotic Interchange)
- Kuchinja mafungu egungwa pasi rose nekuvhara nzira yegungwa pakati pePacific neAtlantic
- Zvinokanganisa mamiriro ekunze, kusanganisira kusimbisa Gulf Stream iyo inokanganisa mamiriro ekunze eNorth Atlantic
Chiitiko ichi chaisangova "kubuda kwebhiriji repasi", asiwo shanduko muhurongwa hwePasi pamwero wepasi rose.
8. Nguva Yechando uye Kuumbwa Kwenzvimbo Yemazuva Ano
Mumakore mamiriyoni apfuura, maAmerica akasangana nenguva dzechando (glacial-interglacial). MuNorth America, chando chikuru chakafukidza Canada nenzvimbo zhinji dzekuchamhembe kweUnited States. Aizi iyi:
– Kuputsa matombo, zvichiita mipata nemadhamu
- Kuisa zvinhu zvevhu, zvichiita nzvimbo yakakura
- Akaita basa guru mukuumbwa kweGreat Lakes
Aizi payakanyunguduka, mwero wegungwa wakawedzera uye wakagadzira mahombekombe emazuva ano, kusanganisira magungwa, rwizi rwe deltas, uye mapani egungwa.
South America yakasanganawo nemigumisiro yeIce Age, kunyanya muAndes nenzvimbo dzekumaodzanyemba dzakadai sePatagonia. Matombo echando akaumba mipata yakaita seU, mafjords, nemakungwa emakomo anoratidza nzvimbo iyi.
9. America Ichiri "Kuumbwa"
Kunyangwe zvichinzwika senhoroondo yekare, kuumbwa kweAmerica hakuna kumira. Maplate eTectonic achiri kufamba:
- Atlantic ichiri kuwedzera
– Nzvimbo iri kumadokero ichiri kugadzira makomo uye ichikonzera kudengenyeka kwenyika.
- Mabasa ekushandura akadai seSan Andreas ari kuramba achichinja nzvimbo dzepasi
- Dunhu reCaribbean richiri kuomarara nekuda kwekuroverana kudiki kwemaplate
Izvi zvinoreva kuti chimiro chekondinendi yeAmerica chinogona kunge chakasiyana mune ramangwana. Mumamiriyoni emakore anotevera, zvikamu zvekondinendi zvinogona kusimuka, kunyura, kana kuchinja zvakanyanya kubva panzvimbo yazviri pari zvino.
Mhedziso
Nhoroondo yekuumbwa kweAmerica inyaya refu yekuchinja kweNyika nguva dzose. Kubva pakuumbwa kwemakondinendi ekare (cratons), kusvika pakubatana kwemakondinendi makuru sePangaea, kusvika pakupatsanurwa kwakakonzera Atlantic Ocean, kusvika pakuumbwa kwemakomo makuru ekumadokero, kusvika pakumuka kweIsthmus yePanama uye kukanganisa kwenguva dzechando—zvese izvi zvakaumba maAmerica sezvatinoziva nhasi. Kunzwisisa maitiro aya kunotibatsira kuona kuti makondinendi haana kumira, asi mhedzisiro yekuchinja kwemapuraneti kuri kuramba kuchishanda nanhasi.
Kana muchida, ndinogonawo kugadzira chinyorwa chino nenzira inonzwisisika kuvadzidzi, kana kuwedzera nguva yezvidzidzo zve geology (gore negore) kuti zvive nyore kudzidza.
