Download Demise of the Dinosaurs Powerpoint

By Stephen Monahan
 Discovered by Luis and
his son Walter Alvarez in
1980
 Proposed Asteroid
Theory
 Lack of evidence of other
opposing theories, made
volcanic theory the given
cause
 Correlates to knowledge
about other mass
extinctions
 A piece of limestone
 From "great dying“
 Neutron activation
analysis (NAA) by Asaro
and Michel
 Allowed for precise
measurements
 Discovered twenty-five
time increase of iridium
 Unlikely that so many
species killed in short
period of time
 Single event of the
asteroid hitting the earth
or a succession of events
caused the extinction
 Time is often evidence to
the contrary
 Gerta Keller studies of
many rock formations
 Fossil remains to date
surrounding geologic
features
 El Penon, 52 species
discovered in the layer
below asteroid layer found
in layer above
 Concluded that volcanoes
was more likely
 In 1991, scientists found a impact
crater
 New data from debris suggest
extinction and impact happened
within 33,000 years period
 A small layer of sediment
around the world contains a lot
of iridium
 Collection of 45 scientists from
different fields
 Went through each possible
cause
 The impact from the




asteroid made subsurface
rocks unstable by
disturbing them
Dust sent into the
atmosphere from the
impact
Significant variations in
the climate
Global wildfires
Modern View is not
unanimous but mostly to
Asteroid Theory