A 200 metre long, 10 metre high basalt wall has been found in the Pescadores archipelago, 25 miles west of Taiwan’s main island. It looks as though it is made up of thousands of pillars packed together. Similar walls exist on land, most notably the Giant’s Causeway in Ireland.
Although it looks a lot like a city wall, scientists believe it was created by a volcanic eruption, perhaps 1800 years ago. It reminds me a bit of the underwater structure off Yonaguni in Japan, although the jury is still out on whether that is also a natural occurrence or whether it was man-made.
There is a Reuters article on the Taiwan wall here, and a video on the BBC’s website. You can read a bit more about Yonaguni here.
