Glasford crater
Template:Short description Template:Infobox terrestrial impact site
The Glasford crater, also known as the Glasford Disturbance, Glasford Structure,<ref>Template:Cite book</ref> and Glasford Cryptoexplosion Structure<ref>Template:Cite journal</ref>, is a buried impact crater in southern Peoria County, Illinois, in the United States.<ref>Template:Cite Earth Impact DB</ref> It is one of two known meteor craters in Illinois.<ref name=":0">Template:Cite web</ref>
It is Template:Convert in diameter and the age is estimated to be less than 430 million years (Silurian or younger).<ref name=":1">Template:Cite journal</ref><ref>Template:Cite web</ref> It was formed in a marine environment in the Late Ordovician period.<ref name=:1/><ref>Template:Cite journal</ref> The meteorite is estimated between 50 and 90 million tons and likely originated in the asteroid belt between Mars and Jupiter.<ref name=":2">Template:Cite news</ref>
The Glasford crater was discovered by the Central Illinois Light Company (formerly CILCO, now Ameren) while drilling wells for underground natural gas storage.<ref>Meteorite Research - Progress Report Template:Webarchive, Research Subcommittee, Associate Committee on Meteorites, National Research Council of Canada, 1967</ref><ref name=":3">Template:Cite web</ref> It is not visible from the surface, as it is covered by agricultural farmland.<ref>Template:Cite web</ref><ref name=":3" /> The present day location is near the intersection of Cowser and Kingston Mines roads.<ref name=":2" /> It was identified in 1963 as a probable impact structure.<ref name=":1" /><ref>Template:Cite news</ref> In the 1980s, scientists identified shatter cones.<ref name=":1" /> Geologists estimate the meteor released a large amount of energy, roughly equivalent to 20,000 nuclear bombs, 460 million tons of TNT, or two to three times the energy of the Mount St. Helens eruption.<ref name=":3" /><ref name=":2" />
According to research by geologist Charles Monson, the Glasford crater may be connected to the Great Ordovician Meteor Shower.<ref name=":4">Template:Cite web</ref> Dr. Birger Schmitz's study suggests that the dust from the meteor impact may have impacted Earth's climate and contributed to the mid-Ordovician Ice Age.<ref name=":0" /><ref name=":4" />