|WILDFIRE EFFECTS: Large impact cratering events can produce wildfires over vast portions of the Earth's surface. In the case of the Chicxulub impact event that has been linked to dinosaur extinction, the wildfires affected vast portions of the world and sent plumes of smoke into that atmosphere that darkened the planet.|
These wildfires were devastating. Not only did they consume vegetation,
they also destroyed important habitats and food resources for animals,
possibly leading to the collapse of the food chain in continental regions.
This and other impact-generated environmental effects led to the extinction
of over 75% of the species.
|THE EVIDENCE: The first evidence of these fires was found by Wendy Wolbach, Ed Anders, Roy Lewis, and Iain Gilmour at the University of Chicago. They found traces of the soot in the rocky remnants of the impact event that were scattered in places like Denmark, New Zealand, Spain, Turkmenia, and the United States, far from the point of impact in what is now Mexico.|
|The fossil record also contains a biological signature of the wildfires. A detailed study by Tschudy and Chuck Pillmore with the U.S. Geological Survey discovered a fern-spore spike in the rock record. This is an anomolous concentration of the spores shed by growing ferns, relative to the pollen shed by other types of plants (e.g., angiosperms) that grew soon after the impact event.|
|This fire-recovery pattern is similar to that seen in some parts of the world today. For example, after a forest fire in New England, ferns are often the pioneering plant that grows first. Many years are needed for birch forests, and eventually hardwood maple forests, to recover.|
New model calculations of these processes by David Kring (Univ. Arizona) and Daniel D. Durda (Southwest Research Institute) show how the fires were ignited, initially around the impact site and, soon afterwards, at a spot on the opposite side of the Earth where a concentrated stream of debris rained back down on Earth. As the Earth rotated below the impact ejecta, the fires spread to the west of these two locations over the following hours to days. Fires were ignited in North America, South America, Africa, and Asia. Depending on the trajectory of the impacting asteroid or comet, and details in the expanding plume of impact ejecta, fires may have also been ignited in Antarctica or Europe.
These wildfires poured vast amounts of pollutants into the atmosphere.
Based on the amount of soot found in sediments deposited soon after the
impact event, it has been estimated that ten trillion metric tons of carbon
dioxide (CO2), one-hundred billion tons of methane (CH4), and one trillion
tons of carbon monoxide (CO) were pumped into the atmosphere. These
pollutants contributed to the environmental catastrophe of the Chicxulub
impact event and may have been partly reponsible for the mass extinction
Click here to link to more information about impact cratering processes.
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.
Movie of impact generated wildfires compiled by Daniel D. Durda. br>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).