Serpent Mound Cryptoexplosive Structure
Posted by: 
Mr. 0
N 39° 01.517 W 083° 25.797
17S E 289648 N 4322391
This is a 5 mile wide complex crater created approximately 256 million years ago. Located in southwest Ohio at the intersection of Adams, Highland, and Pike counties.
Waymark Code: WM20B7
Location: Ohio, United States
Date Posted: 08/13/2007
Views: 76
The general area here has been of interest to current cultures since the mid 1800's. The Serpent Mound was discovered here and since then much research of the mound and surrounding areas has been conducted.
After the mound was discovered it was noticed that the geology of the surrounding area differed greatly from that found elsewhere in Ohio. John Locke, who explored the area in the 1830's noted that “a region of no small extent had sunk down several hundred feet, producing faults, dislocations and upturnings of the layers of the rocks." At the time he thought the he had discovered a "sunken mountain." Some of the areas look like they have slid straight down while others have risen almost 1,000 feet straight up. Over time more evidence has been found. Eventually in the 1970's, core samples were taken from the crater area. Scientists have found iridium at levels up to 10 times that normally found in the Earth's crust, soot from what may be scorched limestone, deformed grains of sand, and quartz with microscopic fractures. In addition "shatter cones" have been found from the surface down similar to those found in Nevada at nuclear weapon test sites.
The crater is most easily accessed publicly at the Serpent Mound Earthworks which sit on a plateau in the southwestern portion of the crater. The NNL page can be found here, and there is additional information found on Wikipedia.
Admission is charged to enter the Serpent Mound State Memorial, however the actual crater spans much more area than just the park.