However, the volcanic crater hypothesis didn't satisfy Darwin; he thought the atoll shape was too regular to have been the craters of old volcanos. (paulmacrae.com)
«Lava» features a shaggy old volcano in the middle of the ocean. (washingtonpost.com)
The almost perfectly circular Pilanesberg national park, due to its lying literally in the void of a 1200 million year old volcano crater, lies 150 kilometres north west of Gauteng, virtually on the border of Sun City — one of the biggest draw cards to the area — and, by comparison, receives little of the acclaim it deserves... (blog.sa-venues.com)