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 a special place in Wisconsin, United States. It's an impact crater, which means it was formed when a space rock hit the Earth. This crater is about 40 kilometres (25 mi) southwest of a town called Menomonie. It gets its name from a nearby community, Rock Elm, Wisconsin.
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What is the Rock Elm Disturbance?
Imagine a huge space rock, like a giant boulder, crashing into Earth! That's what happened at the Rock Elm Disturbance. Scientists believe the meteorite (the space rock) was about 170 m (560 ft) wide. It weighed around 9 billion kilograms and was traveling super fast, about 30 km/s (67,000 mph)!
How Big Was the Impact?
When this massive rock hit, it created a crater that is about 6 km (3.7 mi) across. That's pretty big! Scientists have studied fossils found in the rocks that now fill the crater. These fossils tell us that the impact happened a very long time ago, during a period called the Middle Ordovician Period. This was about 455 to 430 million years ago.
Was It Part of a Bigger Event?
Some scientists think the Rock Elm Disturbance might be connected to a much larger event. They believe several meteors might have fallen around the same time, about 469 million years ago. This idea is called the Ordovician meteor event. Other craters that might be part of this event include the Decorah crater in Iowa, the Slate Islands crater in Lake Superior, and the Ames crater in Oklahoma.
What Did Scientists Find There?
When researchers studied the Rock Elm impact site, they made an exciting discovery. They found a very rare mineral called reidite. This mineral forms only under extremely high pressure, like the pressure created during a huge meteorite impact. Reidite is a very dense form of another mineral called zircon (ZrSiO4). Finding reidite at Rock Elm helps confirm that it was indeed formed by a meteorite impact. This rare mineral has only been found at three other massive meteorite impact sites around the world.
Images for kids
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Rock Elm Disturbance as mapped by William S. Cordua in 1987. The outer line shows how far the crater reaches, and the inner line shows the central uplift.
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Blue Rock, a part of the Prairie du Chien sandstone that has been broken and shifted. You can see it from the Underlook Trail at Nugget Lake County Park. Usually, this type of rock forms in flat layers.
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This is what the disturbance area looks like from County Highway HH and County Road CC near Plum City, Wisconsin.
