Naru Okushi
Fascinating formations of beachrock
At the tip of the westernmost peninsula on Naru Island, Okushi is known for one of the largest and most interesting beachrock formations in the Goto Islands. Beachrock is formed when sand and gravel is cemented together by calcium carbonate or other carbonate materials, and is usually found in tropical or semitropical areas. Some of the beachrock here has been precisely dated, as it includes manmade artifacts, largely shards of distinctive pottery from the Jomon period (10,000–300 BCE). The pottery found here is estimated to be about 6,000 years old.