Baengnyeongdo, Daecheongdo, and Socheongdo were originally a part of Ongjin peninsula, but they were separated to become islands due to the rise of sea level. Average altitude of these islands is 50~100m, and the place at Bukpo-ri, Baengnyeong-myeon, is the highest point in this area with altitude of 184.1m. Daecheongdo's shore is made of coastal sand dune, and it is made by sand piling up on the sandstone about 1m.
Degenerated sedimentary rock is wide spread on the whole areas of Baengnyeongdo and Daecheongdo. Also, some amount of alkaline hornblende and granitic gneiss are found at the northeast part of Baengnyeongdo Noticeably, the basalt found in this area is the same kind as those found in Jeongok, Cheorwon, Ullungdo, and Jeju-do.
Baengnyeongdo area is composed of many kinds of soils. The reason why this area is composed of many kinds of different soils with different characteristics is that there are various basic materials such as sandstone, granitic gneiss, and basalt. This area is mainly occupied with a black pine, and oak, a false acasia, and a sumac. However, most forest here is aged less than 20 years, and product capacity of these forests is relatively low.
Quality of Water
The average pH of the streams in this area is pH6.88, and dissolved oxygen is 10.5mg/l. The streams here all satisfy the standards for the first quality streams, and they are also suitable for inhabitation of aquatic organisms with plenty of plankton.