【A small trip around submarine volcanoes and Coast vegetation to Benten Island】 　In the western and southern parts of the Izu Peninsula, the ejecta of ancient submarine volcanoes is widely distributed. After a long period of submarine volcanoes, the whole of Izu was subjected to uplift and erosion, allowing us to see firsthand the inner structure of the volcano, which should have been buried underground. 　If you walk a short distance from here towards the sea, you will There are a small mountain called Bentenjima. Originally, it was an island called Ancient Island (Sea Bream Island), but it was connected to the land by estuary construction in 1957. 　Walking along the promenade of about 200 meters around the island, you will notice that the rocky area is a collection of many angular rocks. When lava streams down the ocean floor during a submarine eruption, the lava is rapidly cooled by water and breaks into pieces. Scene how a glass cup containing a hot drink breaks when dipped in cold water. What is formed in this way is called "cooling fracturing lava", and it is evidence that lava streams through the water. 　The forest of Ubamegashi that grows naturally in the rocky area is also one of the highlights of Benten Island.