.
Numerous dozen small effect craters, 10– 70-m in size, have actually been found in southeastern Wyoming.
After finding the first craters, the team initially presumed that they are a crater-strewn field, formed by the breakup of an asteroid that entered the environment. All of the craters found so far are situated 150– 200 km from the presumed main crater and were formed by blocks that were 4– 8-m in size that struck the Earth at speeds of 700– 1000 m/s. The team approximates that the source crater is about 50– 65 km in diameter and must be deeply buried under more youthful sediments in the northern Denver basin near the Wyoming-Nebraska border.
A team of U.S. and German geoscientists found these ancient craters in exposed sedimentary layers from the Permian period (280 million years ago). After finding the first craters, the group initially thought that they are a crater-strewn field, formed by the separation of an asteroid that entered the environment. With the discovery of more and more craters over a broad area, this analysis was ruled out.
Drone images of craters formed at Sheep Mountain. Credit: Kent Sundell, Casper College.
A lot of the craters are clustered in groups and are aligned along rays. Several craters are elliptical, allowing the restoration of the incoming paths of the impactors. The reconstructed trajectories have a radial pattern.
Drone picture of crater formed at Sheep Mountain. Credit: Kent Sundell, Casper College.
” The trajectories show a single source and reveal that the craters were formed by ejected blocks from a large primary crater,” stated project leader Thomas Kenkmann, teacher of geology at the University of Freiburg, Germany. “Secondary craters around larger craters are popular from other planets and moons however have actually never ever been found on Earth.”.
Drone picture of crater formed at Sheep Mountain. Credit: Kent Sundell, Casper College.
The team determined the ballistic trajectories and utilized mathematical simulations to model the development of the craters. All of the craters discovered so far lie 150– 200 km from the presumed main crater and were formed by blocks that were 4– 8-m in size that struck the Earth at speeds of 700– 1000 m/s. The team approximates that the source crater is about 50– 65 km in size and need to be deeply buried under younger sediments in the northern Denver basin near the Wyoming-Nebraska border.
Reference: “Secondary cratering on Earth: The Wyoming impact crater field” by Thomas Kenkmann, Louis Müller, Allan Fraser, Doug Cook, Kent Sundell and Auriol S.P. Rae, 11 February 2022, Geological Society of America Bulletin.DOI: 10.1130/ B36196.1.