“Impact Craters Under the Sea”. Earth2Class Workshops for Teachers Lamont-Doherty Earth Observatory Originally presented 14 Dec 2002. Guest Scientist. Dr. Dallas Abbott Visiting Assistant Professor, Barnard College and LDEO Research Scientist firstname.lastname@example.org .
Earth2Class Workshops for Teachers
Lamont-Doherty Earth Observatory
Originally presented 14 Dec 2002
Dr. Dallas Abbott
Visiting Assistant Professor, Barnard College and LDEO Research Scientist
The primary focus of Dallas Abbott’s research is the thermal history of the earth, and the manner in which heat transport through the crust and upper mantle influences geological processes, both ancient and present-day.
An important theme centers about her theory that plate tectonics - meaning sea floor spreading and subduction - has been active over nearly the entire span of earth history, that is, since the early Archean era 4 billion years ago.
The most important consequence of this decrease has been a change in the style of subduction, from predominantly shallow-dipping "buoyant" subduction in the Archean to predominantly steeply-dipping "Andean" subduction today.
Recent research has led Dr. Abbott to investigate data from sea floor studies that may be the result of impacts of asteroids, meteorites, and other extraterrestrial objects. She will provide more evidence from petrologic studies and other techniques during her portion of this program.
Impact craters on land have been known and studied for many years. This STS-9 image of The Manicouagan Crater in northern Canada shows the remains of a collision estimated to have taken place 200 million years ago.
One of the best presentations about impact craters on the Internet is Terrestrial Impact Craters, Second EditionCompiled by Christian Koeberland Virgil L. SharptonThey include descriptions and images from craters on Earth and elsewhere in the solar system
Not exposed at the surface, it has been identified through geophysical studies of the gravitational field. Located at 21.3°N 89.6°W, the structure has a diameter of ~250-280 km. Its age has been calculated at 64.98 ± 0.05 million years
Connections between impacts and mass extinctions provide evidence for the still-unproved theory that such events may be the “metronome that sets the cadence for biological evolution on Earth.” (Koeberl and Sharpton)
NASA’s Jet Propulsion Laboratory provides much more information about impact craters throughout the solar system in their “Welcome to the Planets” web sitehttp://pds.jpl.nasa.gov/planets/
Excellent information and classroom activities have been created by the Hawai'i Space Grant College, Hawai'i Institute of Geophysics and Planetology, University of Hawai'i