Elmar Buchner and Thomas Kenkmann say the key to their finding was tiny grains of “shocked quartz” — basically, quartz that has a different microscopic structure from normal quartz due to undergoing extreme pressure of some sort — that was created by the impact.
Having hiked the superb Syncline Loop last year (trip report), it seems obvious it was a meteor crater.
Yet final proof was quite an accomplishment, I understand.
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Actually, it can be difficult to tell a volcano crater from a meteor impact, and sometimes from other natural wierdness.