Editing Meteor Crater (section)

===Grove Karl Gilbert===
In November 1891, [[Grove Karl Gilbert]], chief geologist for the [[U.S. Geological Survey]], investigated the crater and concluded that it was the result of a [[Maar|volcanic steam explosion]].<ref name="Kring 2007"/> Gilbert assumed that, if it were an impact crater, then the volume of the crater, as well as meteoritic material, should still be present in the crater's rim. Gilbert also assumed a large portion of the meteorite should be buried in the crater and that this should generate a large magnetic anomaly. Gilbert's calculations showed that the volume of the crater and the debris on the rim were roughly equivalent, which meant that the mass of the hypothetical impactor was missing. There were also no detectable magnetic anomalies; he argued that the meteorite fragments found on the rim were coincidental or placed there. Gilbert publicized his conclusions in a series of lectures.<ref name=barringercrater.com>{{cite web|title=Crater History: Investigating a Mystery|url=http://www.barringercrater.com/about/history_2.php|publisher=The Barringer Crater Company|access-date=19 February 2013|archive-url=https://web.archive.org/web/20171231232301/http://www.barringercrater.com/about/history_2.php|archive-date=31 December 2017|url-status=dead}}</ref> In 1892, Gilbert would be among the first scientists to propose that the Moon's craters were caused by impact rather than volcanism.<ref name=Cosmic_Debris>{{cite book|last=Burke|first=John G.|title=Cosmic Debris: Meteorites in History|date=1986|publisher=University of California Press|location=Berkeley|pages=276|isbn=0520056515}}</ref>