CretaceousTertiary Boundary Impact

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Asteroid Impact The Dinosaur Killer
Cretaceous-Tertiary Boundary Impact
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The Fossil Record - Mass Extinction

• The fossil record shows a significant drop in the
  spicies populations of Earth approximately 65
  million years ago.

• This marks the end of the Age of Reptiles
  (Cretaceous period) and the beginning of the Age
  of the Mamals (Tertiary period)

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Evidence of an Impact

• A great deal of evidence supporting the theory
  that the K-T boundary mass extinction was caused
  by an asteroid impact is accumulating.
• Scientists have found
• 65 million year old soot layer around the globe
• an impact site in present day Mexico
• with fractured rock evidence indicating a
  massive impact
• gravitational fluctuations were found in 1991 by
  the Geological Survey of Canada

We will study the evidence and effects at greater
detail later in the year.
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The Location of Chicxulub
Impact site
The position of the continents 65 million years
ago.
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The Evidence at Chicxulub
Gravity Mapping Geological Survey of Canada
Approximately 180 km across
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The Impact Energy
Recall Dcrater kEn where D crater
diameter k impact constant (k 0.057 s2/kg
m) n energy impact exponent constant (n
0.25)
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The Impact Energy
Dcrater kEn
n slope of line
Class data plotted to determine n- and k-values.
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The Impact Energy
Dcrater kEn
n slope of line 0.26 k 0.067 s2/kg m
Class data plotted to determine n- and k-values.
Values are based on SES 4UI class data from
February 2004
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The Impact Energy
Given Dcrater 180 km 180 000 m n
0.26 k 0.0667
Find Energy
That is equivalent to a 1.2 billion MT nuclear
blast or 12 million of the most powerful nuclear
warheads detonating at once.
MT mega ton 1 MT 4.3 x 1015 J
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The Impactor Size
Given rimpactor ? km E 5.25 x 1024 J v 20
000 m/s RecallDensity mass/vloume Energy
1/2mv2
Find Size
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The Impactor Size
Given rimpactor ? km E 5.25 x 1024 J v 20
000 m/s D 3000 kg/m3
Find Size
Based on data from our impact-flour lab, the
asteroid that killed the dinosaurs had a diameter
of approximately 26 km.
Values are based on SES 4UI class data from
February 2004
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The End