CLICK HERE to watch a 2-minute YouTube video: Scenes from the Belt Meteor Crater
This photo, taken about 20 miles southeast of Great Falls (near Belt), shows an unusual circular hole known as the Belt Meteor Crater. Despite its name, the crater, which measures 100 feet across and 35 feet deep, was not made by a meteorite slamming into the surface . . . In fact it has nothing to do with rocks from space! Actually, the hole is a type of formation that geologists refer to as a sinkhole, and it was caused by changes that took place in rocks that lie beneath the surface.
Like Swiss cheese . . .
Eventually these caves collapse, and that is what happened to form the meteor crater and other sinkholes. In the case of the meteor crater, a fairly large cave must have formed in the limestone not far beneath the prairie surface. Eventually layers of sandstone above the cave collapsed onto the cavern floor to form the sinkhole. Watch the short slideshow below to see how this happens.
A deep blood kettle . . .
Below: The Monarch Sink . . .
CLICK HERE to watch an ABC News video about a sinkhole in Florida (May 2012). Sinkholes are so common in Florida that some people purchase sinkhole insurance.
Photo by Dr. David Baker
NOTE: Both the Belt Meteor Crater and the Monarch Sink are located on private property. Please do not trespass.
Terms: dissolution, Mississipian Period
|*Map of Sinkholes in Florida|
|*More about sinkholes (USGS)|
|Books related to Montana Earth Science|
|*Map of the world about 350 million years ago|
Earth Science Teacher at Helena High School