An Ending Trope common to B Movies of the 50s and 60s, especially those involving a Lost World, in which an earthquake, volcano, avalanche or some similar (usually natural) disaster destroys the Lost World. This can be hinted at in advance, but as often as not it appears out of the blue to threaten the main characters and necessitate a hasty departure. Also note that the disaster always manages [...] [tvtropes.org]