METEORITE OR METEOR-WRONG: USING SOIL STRATIGRAPHY TO PROVIDE EVIDENCE FOR A NEW HOLOCENE-AGED IMPACT CRATER, WASHINGTON COUNTY, IDAHO

Of the ca. 190 confirmed impact craters on earth, only 19 are shown to have formed during the Holocene. Our student research team at the College of Western Idaho has the opportunity to research a unique geomorphic feature in Washington County, ID. This circular depression is roughly 20m in diameter and has an intact “rim” elevated 1m from the surrounding alluvial surface. During initial investigation of soil samples collected along the “rim”, we discovered that approximately 20% of the larger soil separate was magnetically susceptible. The shape and profile of this feature, along with a high percentage of magnetically susceptible material found suggests that this could be the result of a meteor impact. Unequivocal confirmation of a new impact crater can be elusive; the presence of a predictable pattern of ballistic ejecta is generally seen as diagnostic of impact. In this paper we will further examine the soil structure surrounding this feature with a specific focus on the potential presence ballistic ejecta in the form of magnetic and/or carbonaceous material. Establishing the presence and aerial extent of an eject curtain will provide further evidence to confirm this feature as a new Holocene aged impact crater.