Des Plaines crater

The Des Plaines crater or Des Plaines disturbance is recognized as an impact crater in Illinois, United States. It is located beneath the eastern part of the city of Des Plaines, which is a suburb of Chicago.^[1][2]

It is 5.5 miles (8.9 km) in diameter and the age is estimated to be less than 280 million years (Permian or younger). The crater is buried beneath 75 to 200 feet (23–60 m) of glacial till and can only be seen as a series of faults and deformation in well logs and seismic surveys.^[3] Faulting in the structure has produced as much as 600 feet (180 m) of vertical displacement.^[3] Subsurface strata of Cambrian through Pennsylvanian age has been faulted and tilted by the event.^[1][4] The anomalous area was first noted by water well drillers in 1893 who noted an absence of water in a 1600 foot deep well. Prior to being recognized as an impact structure the feature was referred to as a cryptoexplosion structure or cryptovolcanic structure as were several others in the midwestern U. S.^[4] The upfaulted central portion^[4] and the presence of shatter cone structures support the impact origin.^[1]

References

1. ^ ^{a b c} Wiggers, Raymond (1997) Geology Underfoot in Illinois, Mountain Press Publishing Company, Missoula, Montana, pp. 74, 82-83 ISBN 978-0878423460
2. ^ Earth Impact Database
3. ^ ^{a b} Faulting and the Des Plaines Disturbance, Illinois Geological Survey
4. ^ ^{a b c} Emrich, G. M. and R. E. Bergstrom, Des Plaines Disturbance, Northeastern Illinois, GSA Bulletin; August 1962; v. 73; no. 8; p. 959-968

Coordinates: 42°3′N 87°52′W / 42.05°N 87.867°W / 42.05; -87.867