Rock Elm Disturbance


The Rock Elm Disturbance is an impact crater in Wisconsin, United States, roughly southwest of Menomonie. The disturbance is named for Rock Elm, Wisconsin, a nearby community.

Description

The meteorite is estimated to have been in diameter with a mass of and impact velocity of. The crater is in diameter, and fossils found in the rock filling the crater suggest it dates to the Middle Ordovician Period, about 455 to 430 million years ago.
It may be one of several Middle Ordovician meteors that fell roughly simultaneously 469 million years ago, part of a proposed Ordovician meteor event that includes the Decorah crater in Iowa, the Slate Islands crater in Lake Superior, and the Ames crater in Oklahoma.

Composition

Researchers discovered a rare high-pressure mineral called reidite at the Rock Elm impact site. Reidite is a dense form of zircon and has been found in three other massive meteorite impacts.