Death from Outer Space, Did an Asteroid Impact Wipe out

the Dinosaurs?

The asteroid Gaspra - 7x7x12 miles

A Gallery of Asteroids

Was it really an asteroid? We must

have multiple working

hypotheses!

Dinosaurs forgot to board the Ark

K/T Boundary 66 MYAge of Dinosaurs

Geologic Time Scale

K-T extinction record

Wyoming

The K/T impact clay layer, Gubbio, Italy. Iridium anomaly first found here.

K = Cretaceous

T = Tertiary

K

T

Iridium anomaly in the K/T rocks at Gubbio, Italy, in parts per billion (PPB).

K/T boundary

20 cm

10 cm

0 10

PPB

0

The K/T boundary in New Mexico is marked by the white claystone just above the head of the hammer.Claire Belcher, Geology Department, University of London

The white claystone layer marks the K/T boundary

The K/T boundary in Spain

Known distribution of sites with K/T Iridium anomaly

Map of major impact sites in North America

The Berringer Crater in Arizona, 50,000 years old. 4000 ft across -- formed by 100 ft meteorite.

Why craters are so much larger than the objects that make them. Like shooting a bullet into a soft target.

The Manicougan Crater in Quebec,late Triassic in age -- 100 km diameter

Gosses Bluff, Australia. Crater age is 142 Ma, but no mass extinction.

A 4 km wide asteroid hit

America at the end of the Eocene,

35 m.y. ago

the Chicxulub Crater

Late Cretaceous Paleogeography

Gravity anomaly map of Yucatan area

3D representation of gravity anomaly

Another representation of the gravity anomaly on the Yucatan Penninsula: the Chicxulub Crater

Tektites from the asteroid impact –melted rock

Enlargement of a tektite from the Atlantic sea floor

Tektites from the K/T boundary in New Jersey

Map showing distribution of tektites by size. Tektites are largest near Yucatan.

Shocked quartz from the asteroid impact

The impact: 66 MY ago

The 6-mile diameter asteroid heading towards Earth, 66 MY ago

The start of a bad day, 66 MY ago

Velocity = 20 km/s or 40,000 mph

Kinetic energy about to be converted to thermal energy

Impact on the Yucatan Peninsula!

The power of millions of atomic bombs

The K/T impact released more energy than the World’s Nuclear Arsenal

Primary Killing Mechanisms: Two Hypotheses

• Infrared thermal pulse “broiled” exposed animals for several hours after the impact.

• A massive dust cloud blanketed the Earth, blocking sunlight. This caused a collapse of the food chain and severe global cooling.

Broiled Dinosaurs

Thermal radiation 7X greater than the sun

Fiery debris falls back to Earth over large areas starting forest fires

Worldwide forest fires consumed about 30% of all terrestrial biomass.

Blast wave and dust cloud from the impact

Dust from the impact, and smoke from fires, blanketed the Earth and blocked the sunlight.

Temperature anomaly map 15 days after impact

Temperature Change

The Yucatan, a few days after impact

The crater about 1000 years after impact

Looking for evidence of the Yucatan impact outside the Caribbean. The Ocean Drilling Project recovers cores off the east coast of Florida in 1997.

The drilling ship can send a drill string to the ocean floor and recover core.

Cores layed out on the ship

Section of core with K/T boundary interval.

geoweb.princeton.edu/.../massex.html

Forams from the Cretaceous

Forams from the Tertiary