Rock Elm Disturbance facts for kids
North American Middle Ordovician impact craters, which may be part of the Ordovician meteor event. Key: 1: Ames crater, 2: Decorah crater, 3: Rock Elm Disturbance, 4: Slate Islands crater
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| Impact crater/structure | |
|---|---|
| Confidence | Confirmed |
| Diameter | 6 km (3.7 mi) |
| Age | 430-455 Ma Middle Ordovician |
| Exposed | - |
| Drilled | - |
| Bolide type | Ordovician meteor event? |
| Location | |
| Coordinates | 44°43′N 92°14′W / 44.717°N 92.233°W |
| Country | United States |
| State | Wisconsin |
| District | Pierce County |
| Municipality | Rock Elm |
 Location in the United States
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The Rock Elm Disturbance is an impact crater in Wisconsin, United States, roughly 40 kilometres (25 mi) southwest of Menomonie. The disturbance is named for Rock Elm, Wisconsin, a nearby community.
Description
The meteorite is estimated to have been 170 m (560 ft) in diameter with a mass of 9×109 kg (2.0×1010 lb) and impact velocity of 30 km/s (67,000 mph). The crater is 6 km (3.7 mi) 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 (ZrSiO4) and has been found in three other massive meteorite impacts.
Images for kids
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Rock Elm Disturbance as mapped by William S. Cordua in 1987. Outer line is extent of crater and inner line is central uplift.
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Blue Rock, a faulted portion of Prairie du Chien sandstone, is visible from the Underlook Trail at Nugget Lake County Park. Note that this sedimentary rock typically demonstrates horizontal stratification.
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The disturbance area as seen from County Highway HH and County Road CC near Plum City, Wisconsin
