(1) Mass extinctions on Earth
(2) Asteroid Impact and the K-T Event
(3) Dr. Elliott's work at Stevns Klint
The Earth has suffered a series of mass extinction events recorded in the
geological record. These probably had both TERRESTRIAL (climate change, flooding,
volcanic activity, disease, loss of biological diversity) and
EXTRATERRESTRIAL (asteroid impacts) causes.
The most recent event occurred 65 million years ago at the boundary
of the Cretacious - Tertiary ages (K-T) in which 11 percent of all species
were lost (including the demise of the dinosaurs).
The evidence now points to an impact of a 10 km size body near the
Yucatan peninsula in Mexico (crater now covered by 2 - 3 km of sediments).
The impact destroyed the asteroid and sent a cloud of debris into the
stratosphere (which settled all around the globe).
Dr. Elliott investigated the clay deposits found in exposed K-T boundary
rocks (debris from the impact) at
Stevns Klint in Denmark.
He studied the smectite clay and found evidence of meteoritic proportions
of iridium and gold. High magnification images of the samples show
evidence of glasses formed in the impact which slowly tranform into
He also found evidence of
small dark patches of iron oxides with
meteoric proportions of metals. These are probably remnant fragments
of the actual asteroid that collided with Earth.