![](http://3.bp.blogspot.com/_r0K6n0OaIZM/SSYvqcJ9cjI/AAAAAAAAAHI/rAZqTz4IrN0/s320/Crack_Alley.jpg)
It is estimated that the crack has remained open for a thousand years. Open cracks or fissures in the earth's surface are not uncommon; they occur fairly often as the result of earthquakes or volcanic activity, but they usually become filled with rock rubble or lava and disappear in a very short time. A large fissure that stays open for hundreds of years is, therefore, a rare feature.