Archive for the 'Former islands' Category

Disappearing Indian islands

Sunday, December 24th, 2006

An inhabited island in the Sundarban region of India have disappeared, and their submergence is being blamed by some on global warming-induced sea level rise.

The Independent (UK) reports the disappearance of Lohachara as the first sinking of an inhabited island caused by climate change, and suggests that 12 islands with a population 70,000 are in danger.

While the danger of rising seas appears real, islands disappear (and appear) in this deltaic region on the Bay of Bengal all the time, and it might be hard to pin this particular instance on the small sea level rise that has occurred so far.  Indeed, Lohachara might be a char — the Bangladeshi name for the notoriously shifting and often temporary river deposits that land pressure forces desperate people in the region to live on.

Ghost island off San Francisco

Wednesday, July 12th, 2006

I have always been intrigued by ancient islands now drowned under the waves by rising seas.

I was looking at the lovely new Geology of the San Francisco Bay Region, a guidebook by Doris Sloan, and noticed such an island about 20 miles off Point Reyes, northwest of the city.

Between 18,000 and 14,000 years ago, the rising ocean cut off a hill on the coastal plain, forming an island. Animals would have become stranded there, and over the next few thousand years some might have begun to evolve in their isolation. But the island continued to shrink, and by 11,500 years ago had been reduced to a few small islets. They submerged by 10,500 years ago, and the life of the place came to an end.

The remains of the island can still be seen, as Cordell Bank, where divers swim amidst the pinnacles that were the last remains of the island before it was gone.

[geology]