Introducing the highlights (11 geosites) of the Middle Izu area

The highlights of the Middle Izu area
Joren Falls
Mt. Hachikuboyama and Mt. Maruyama erupted about 17,000 years ago and the lava from Mt. Hachikuboyama formed the Kayano plateau. It also flowed into the Hontani River and created Joren Falls. The cliff beside the waterfall has columnar joints that were formed when lava cooled and contracted. You will see a beautiful scenery of columnar joints and waterfalls there.
Hachikuboyama volcano
Hachikuboyama Volcano, which erupted about 17,000 years ago, belongs to the Eastern Izu Volcano Group. It is a scoria cone made by piled-up scoria (magma splash). You will see this pudding-shaped mountain from the parking lot of Joren Falls and the roadside station "Amagigoe". Walking the mountain trekking road, you will reach the top of the mountain and a cone-shaped crater.
Namesawa Valley
In the bottom of the Namesawa Valley you will see smooth expanse of flat rock. It is the lava from Namesawa Volcano. Its surface has beautiful joints (cracks made when lava cooled) and it was polished by the flow of the Namesawa River over a long period of time. There is “Ryushinotaki” or Dragon-shaped Falls at the confluence of the Namesawa River and the Hontani River.
Asahidaki Falls
Asahidaki Falls was formed by the magma that rose from underground and pierced the thick pumice layer, that accumulated around Shuzenji Spa. The magma contracted on cooling and made columnar joints. The pumice layer of submarine volcanos was eventually washed away by erosion, and we can see the hexagonal cross-sections of the columnar joints on the wall behind the waterfalls.
Mt. Katsuragiyama
Deep inside a volcano, there is a path of magma through which magma flows. When the path is raised due to crustal upliftment or other mechanisms, it is called “volcanic neck”. Mt. Katsuragiyama is a volcanic neck of a submarine volcano. From the top of the steep mountain that has been eroded for a long time, you will get a fine view of Mt. Fuji, Mt. Hakone and the mountains of Izu.
More (6 left)
Kanogawa Drainage Ditch
The Kano River, which flows from south to north in northern Izu, becomes narrow in the downstream as it is blocked by the sediments from Mt. Fuji and other mountains. It often caused floods, therefore control of the river had been an urgent issue to be solved. Owing to this drainage channel that was constructed to discharge the river water into the sea, serious flooding has been prevented.
Old Amagi Tunnel
Mt. Amagi, favored with abundant water, is a mountain of blessings. At the same time, it had been a topographic obstacle separating the southern and northern parts of Izu. Even if a new road to cross the mountain was constructed, when it rained heavily, it collapsed and became impassable. The tunnel, which had been an eagerly awaited wish of the people in Izu, was finally opened in 1905.
Darumayama Kogen Rest House
Mt. Daruma, which rises in the northwestern part of the Izu Peninsula, is one of the largest volcanoes representing Izu. It was created by the eruption about 1 million to 500,000 years ago. From the observation deck, you will see various types of volcanoes, from the time when Izu was submarine volcanos to the present. You will get a fine view of Mt. Fuji and Mt. Tanzawa in the distance.
Hachoike Pond
Hatchoike Pond lies in the innermost valley of Amagi Volcano, which erupted about 800,000 to 200,000 years ago. It is a fault lake formed by the deviation of the active fault and it accumulated water. Along the gentle ridges of Amagi Volcano around Hatchoike Pond, you can enjoy trekking through the primeval forests such as beech and himeshala.
Shuzenji Onsen (Spa)
Shuzenji Spa is located along the valley of Daruma Volcano, which repeated eruptions until about 500,000 years ago. Under the ejecta of Daruma volcano the pumice layer of submarine volcanoes is distributed. The Katsura River eroded the valley and eventually exposed the riverbed of pumice layer. The historic Shuzenji hot spring, which Kukai is said to have let flow out, spouted from those old strata.
Sukumoyama volcano
Sukumoyama volcano, which erupted 131,000 years ago, is a part of the northernmost part of the Eastern Izu Volcano Group. The cross-sections of the scoria cone are visible on some of the cliffs that were cut open to construct roads. There is a trail that leads to the top of the mountain and from the observation deck, you will enjoy a 360-degree panoramic view.