The term cryptoexplosion structure (or cryptovolcanic structure) means an explosion of unknown cause. The term is now largely obsolete. It was once commonly used to describe sites where there was geological evidence of a large scale explosion within the Earth's crust, but no definitive evidence for the cause such as normal volcanic rocks

Volcano

2. Bedrock3. Conduit 4. Base5. Sill6. Dike7. Layers of ash emitted by the volcano8. Flank| 9. Layers of lava emitted by the volcano10. Throat11. Parasitic cone12. Lava flow13. Vent14. Crater15...

. These sites are usually circular with signs of anomalous rock deformation contrasting with the surrounding region, and often showing evidence that crustal material had been uplifted and/or blown outwards. The assumption was that some unusual form of volcanism, or a gas explosion originating within the crust, was the cause. The use of the term went away with the rise of the science of impact crater recognition in the late 20th Century. Most structures described as cryptoexplosions turned out to be eroded impact crater

Impact crater

In the broadest sense, the term impact crater can be applied to any depression, natural or manmade, resulting from the high velocity impact of a projectile with a larger body...

s, caused by the impact of meteorite

Meteorite

A meteorite is a natural object originating in outer space that survives impact with the Earth's surface. Meteorites can be big or small. Most meteorites derive from small astronomical objects called meteoroids, but they are also sometimes produced by impacts of asteroids...

s. Today geologists discount former cryptoexplosion theories.

See also

• Impact crater
  Impact crater
  In the broadest sense, the term impact crater can be applied to any depression, natural or manmade, resulting from the high velocity impact of a projectile with a larger body...
  
  
• Impact structure
  Impact structure
  The term impact structure is closely related to the terms impact crater or meteorite impact crater, and is used in cases where erosion or burial have destroyed or masked the original topographic feature with which we normally associate the term crater...
  
  
• Astrobleme
• Impact event
  Impact event
  An impact event is the collision of a large meteorite, asteroid, comet, or other celestial object with the Earth or another planet. Throughout recorded history, hundreds of minor impact events have been reported, with some occurrences causing deaths, injuries, property damage or other significant...
  
  
• Traces of Catastrophe
  Traces of Catastrophe
  The book Traces of Catastrophe: A Handbook of Shock-Metamorphic Effects in Terrestrial Meteorite Impact Structures, or more commonly shortened to Traces of Catastrophe, was written by Bevan M. French of the Smithsonian Institution. It is a comprehensive technical reference on the science of impact...