In 1990, a group of geologists discovered a large number of shatter cones in southwestern Montana at the Beaverhead site. Shatter cones are a type of metamorphosed rock often found in impact structures (the remains of a crater after a meteor impact and years of Earth activity). Shatter cones can be as small as one inch or rise up to more than six feet tall. They have distinct cone-shaped fracture patterns resembling horsetails.Scientists now believe that the center of the Beaverhead Crater is located in Idaho, around the Challis area, not in Montana, as some geologists had earlier believed, and that the crater is approximately 50 to 90 miles in diameter.
Beaverhead Crater is one of the eight largest impact craters on Earth, and possibly the largest in the United States. Its age is estimated to be about 850 to 900 million years. Other than the original shatter cones found on the perimeter, there is little visible evidence of the meteor crater.
The photo of the shatter cone was taken by Mike Plautz, Science teacher at Hellgate Elementary in Missoula, Montana.
Instructions for logging waymark: A photograph is required of you (or your GPS receiver, if you are waymarking solo) and the place (i.e. a photo of shatter cone). Also submit the coordinates where the photo was taken and describe the location.