英和和英

出典:『Wikipedia』 (2010/07/23 07:38 UTC 版)

英語による解説

引用

The term cryptoexplosion structure (or cryptovolcanic structure) is now largely obsolete, but 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 or meteorite fragments. 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. It was once commonly assumed that some unusual form of volcanism, or a gas explosion originating within the crust, was to blame. Many such structures can now be demonstrated to be eroded impact craters, caused by the impact of large meteorites or comets. There are still anomalous circular structures that await formal identification of their origin, but most geologists discount former cryptoexplosion theories.