thousand years ago, a large 30 to 50 meter diameter iron asteroid impacted the
Colorado Plateau in northern Arizona. The resulting massive explosion excavated
175 million tons of rock, forming a crater nearly a mile wide and 570 feet deep.
here to learn about the geology of the region). While the Meteor Crater*
impact event was too small to cause global environmental effects, its regional
damage would have been significant.
Reconstructing the environment at the time of the impact is important to understanding the context of the devastation. Palynological (fossil pollen) and paleontolgical studies have provided a partial record of the paleoenvironment including the flora (vegetation) and fauna (animals) that lived in the region ~50,000 years ago.
The current data suggests that a juniper-pinyon woodland or forest covered the gently rolling countryside. Large mammals such as mammoths, large ground sloths, bison, camels, tapirs and horses may have lived in the vicinity and been victims of the 20 to 40 megaton blast.
The damage inflicted by the impact was similar to a nuclear bomb blast, but without ionizing radiation damage. The asteroid, bedrock, and any fauna or flora at ground zero would have been vaporized. Bedrock was ejected and overturned out to a distance of 1-2 km (see graphic). The explosive shockwave would have produced winds in excess of 1000 km/hr within 3 to 5 km of the impact (see effects map). These winds would have stripped away grass near the crater and flattened juniper and pinyon trees out to a radial distance of ~14 to 19 km.
The impact shock wave would also have had severe effects on animals in the region. Dramatic differences in the internal vs. external pressures exerted on animal bodies within the shock wave would have caused hemorrhaging (internal bleeding) and edema. Animals would also have been injured by displacement, their bodies propelled a short distance by the shock wave.
Branches, rocks, and other debris was also accelerated by the blast, causing shrapnel-type wounds out to a distance of 10 to 13 km. Vegetation and animals may also have been subject to the thermal emission from the blast, causing burn damage out to a maximum range of ~10km. This intense heat may have started forest fires or range fires, although no fire evidence has been reported.
The probable sum of these effects is the destruction of vegetation over an area 800 to 1500 km2. Damage to vegetation would have extended over an additional 200 to 600km2. Animals within 3 to 4 km of the impact site would probably been killed, with maiming injuries extending out to distances of ~16 to 24 km. While these effects are severe, they are confined to the immediate region and did not cause extinctions. In fact, the newly formed bowl shaped depression soon filled with water providing a lake habitat (see graphic) for aquatic plants and animals. Recolonization of the area was probably accomplished in a few to ~100 years.
These types of events, however, are
large enough to destroy a modern city. They occur at an average rate of
about once in 6000 years.
*Footnote: The crater has been
known by several names. Before its impact origin was appreciated, the
crater was called Coon Mountain or Coon Butte. Later it was called Meteor
Crater, which is the popular or common name used today. However, the name
recognized by the Meteoritical Society, composed in part of professional
geologists who study impact craters, is the Barringer Meteorite Crater, in
recognition of the work of Daniel Moreau Barringer who championed an impact
origin for the crater.
This web site is based on information originally created for the NASA/UA Space Imagery Centerís Impact Cratering Series.
Concept and content by David A. Kring and Jake Bailey.
Design, graphics, and images by Jake Bailey and David A. Kring.
Any use of the information and images requires permission of the Space Imagery Center and/or David A. Kring (now at LPI).