In southwestern Wyoming, a number of minor impact craters ranging in size from 10 to 70 meters have been identified. These ancient craters were discovered by a team of geoscientists from the United States and Germany in exposed Permian sedimentary strata (280 million years ago). When the researchers first discovered the craters, they assumed they were part of a crater-strewn landscape created by an asteroid fragmenting in the atmosphere. However, when additional craters were discovered over a larger region, this explanation was ruled out.
Several hundred minor impact craters with diameters ranging from 10 to 70 meters have been identified in southern Wyoming. These ancient craters were discovered by a team of geoscientists from the United States and Germany in exposed Permian sedimentary strata (280 million years ago). When the researchers first discovered the craters, they assumed they were part of a crater-strewn landscape created by an asteroid fragmenting in the atmosphere. However, when additional craters were discovered over a larger region, this explanation was ruled out.
Many of the craters are grouped together and lined up along rays. Furthermore, numerous craters are elliptical, enabling the impactors’ entering routes to be reconstructed. A radial pattern may be seen in the reconstructed trajectories.
“The trajectories reveal that the craters were generated by ejected chunks from a big parent crater,” said study leader Thomas Kenkmann, a geology professor at the University of Freiburg in Germany. “Secondary craters encircling bigger craters are widely known on other planets and moons, but they have never been discovered on Earth,” says the researcher.
The scientists performed mathematical simulations to describe the creation of the craters and computed the ballistic trajectories. All of the craters discovered so far are 150-200 kilometers from the putative source crater and were generated by stones of 4-8 meters in diameter that collided with the Earth at speeds of 700-1000 meters per second. The source crater is estimated to be 50-65 km in diameter and should be firmly buried under younger layers in the northern Denver basin near the Wyoming-Nebraska border, according to the scientists.
