Liancourt Rocks consists of two islets, that are 150 metres apart. These small islands are called West Islet and East Islet. The western islet is the larger of the two islets. Altogether, there are about 90 islets and reefs. The islands and rocks have a volcanic nature. A total of 37 of these islets are recognized as permanent land. The eastern islet formed 4.5 million years ago. Ulleungdo formed 2 million years later. Both are quickly eroding and weathering.