Asteroid/Meteor Theory
One hypothesis in this controversy about what
caused the K-T extinction is believed to be extraterrestrial (out of this world). It is
believed that something sudden caused a catastrophic change. Luis and Walter
Alvarez proposed the main hypothesis in 1980. It is known as the Alvarez
Hypothesis or the “Asteroid Theory”.
The Alvarez
Hypothesis:
A large extraterrestrial object collided with the Earth; its impact threw up
enough dust to cause the climatic change. An asteroid impact can be to blame
for the high iridium layer. Asteroids and other space rocks are
higher in iridium content than the Earth’s crust. Therefore it can be argued that the iridium
layer must be composed of the dust from the vaporized meteor. There is a crater at Chicxulub, on the Yucatan Peninsula of
Mexico that seems to appeared at the time the dinosaurs went extinct.
Other evidence was also
reported: the presence of shocked quartzin the rocks of the K-T
boundary (indicating the passage of a shock wave so powerful that it actually
rearranged the crystal structure of quartz grains), glassy spheres that looked
like impact ejecta (molten rock that solidified into droplets
when cooled), and a soot layer was found in many areas (evidence for widespread
forest fires). The likelihood that massive hurricanes and firestorms would have
raged across the Earth was also hypothesized, adding to the destructive power
of the catastrophe.
