knowt logo

Extinctions, Anomaly, and a Crater

K/Pg (Cretaceous/Paleogene) Extinction

  • the dinosaur killer

  • at least 50% of all species were lost

    • classified as an intermediate mass extinction

  • nothing over 55 pounds on land survives

  • this didn’t just happen to land species

  • marine animals suffered too

    • example: ammonites, marine reptiles

    • 80-90% of marine species were lost

Iridium Anomaly

  • chemical element that’s much more abundant in meteoroids than on Earth

  • last clay layer formed during the Cretaceous is strongly enriched in iridium

  • it was noticed first in Gubbio, Italy, but it was a global phenomenon

The Smoking Gun: Chicxulub Crater

  • years before a crater was discovered, “odd”, melted rocks were found

  • melted rocks weren’t explored further until…

  • gravity survey revealed a 93 mile diameter crater

    • shallow entry (20-30 degrees)

    • 6.8-50.3 mile diameter impactor

Meteorite Effects

  • initial effects:

    • vaporizes everything close by

    • causes wildfires

    • generates tsunamis

  • longer term effects:

    • sunlight shut off

      • photosynthesis effectively stops on land and in oceans for up to several months

  • even longer-term effects:

    • up to 18 degree Fahrenheit global warming

      • water vapor remains in the atmosphere after the dust clears

      • CO2 produced from vaporization of certain rocks during the impact

    • acid rain

      • NOx (oxides of nitrogen) formed due to impact combined with the water in the atmosphere →nitric acid

        • oceans and soils acidified

Extinctions, Anomaly, and a Crater

K/Pg (Cretaceous/Paleogene) Extinction

  • the dinosaur killer

  • at least 50% of all species were lost

    • classified as an intermediate mass extinction

  • nothing over 55 pounds on land survives

  • this didn’t just happen to land species

  • marine animals suffered too

    • example: ammonites, marine reptiles

    • 80-90% of marine species were lost

Iridium Anomaly

  • chemical element that’s much more abundant in meteoroids than on Earth

  • last clay layer formed during the Cretaceous is strongly enriched in iridium

  • it was noticed first in Gubbio, Italy, but it was a global phenomenon

The Smoking Gun: Chicxulub Crater

  • years before a crater was discovered, “odd”, melted rocks were found

  • melted rocks weren’t explored further until…

  • gravity survey revealed a 93 mile diameter crater

    • shallow entry (20-30 degrees)

    • 6.8-50.3 mile diameter impactor

Meteorite Effects

  • initial effects:

    • vaporizes everything close by

    • causes wildfires

    • generates tsunamis

  • longer term effects:

    • sunlight shut off

      • photosynthesis effectively stops on land and in oceans for up to several months

  • even longer-term effects:

    • up to 18 degree Fahrenheit global warming

      • water vapor remains in the atmosphere after the dust clears

      • CO2 produced from vaporization of certain rocks during the impact

    • acid rain

      • NOx (oxides of nitrogen) formed due to impact combined with the water in the atmosphere →nitric acid

        • oceans and soils acidified

robot