Part of the Kozagawa Curved Dike
Tenchugan is part of a large geological structure known as the Kozagawa Curved Dike (Kozagawa Kojō Ganseki). This geological formation extends approximately 22 kilometers from east to west in a curved, bow-like shape. It was created by large-scale volcanic activity approximately 15 million years ago.
During this period, repeated volcanic activity occurred across the Kii Peninsula, and it is believed that a massive caldera was formed. Magma that once flowed through underground channels gradually cooled and solidified. Over an extremely long period, erosion removed the surrounding softer layers of rock, leaving behind the distinctive rock formations that can be seen today.
The Kozagawa Curved Dike also includes famous geological landmarks such as Ichimai-iwa Rock along the Kozagawa River and Hashigui-iwa Rocks. The geological features of the area have been recognized as part of Japan’s notable geological heritage, attracting both sightseers and geology enthusiasts.
Spectacular Rock Formation Created by Nature
Tenchugan is composed of geological materials including rhyolitic pyroclastic rocks and Kumano granite porphyry. Over millions of years, erosion gradually wore away the softer surrounding strata, while the harder rock remained standing. This natural process created the imposing pillar-like formation visible today.
Looking up at Tenchugan from along the Kozagawa River, visitors can appreciate its impressive height and rugged form. On clear days, the contrast between the towering rock and the blue sky is particularly beautiful. The surrounding vegetation also changes with the seasons, giving the landscape a different appearance throughout the year.
Access to Tenchugan
Tenchugan can be reached in approximately 20 minutes by car from JR Kii-Kozagawa Station. The drive through the Kozagawa River area is itself part of the experience, with beautiful mountain scenery and clear river landscapes along the route.
Traveling through the valley provides an excellent opportunity to experience the rich natural environment of Kozagawa Town before arriving at this impressive geological landmark.
Experience the Earth’s History in Kozagawa
Tenchugan is a remarkable scenic attraction where visitors can experience both the grandeur of nature and the geological history of the Kii Peninsula. The enormous rock formation, created through volcanic activity approximately 15 million years ago and shaped by countless years of erosion, offers a fascinating glimpse into the forces that have shaped the landscape.
As part of the Kozagawa Curved Dike, Tenchugan is also an excellent destination for travelers interested in geology, natural landscapes, and outdoor sightseeing. When visiting Kozagawa Town, be sure to take time to admire this impressive rock tower and experience the extraordinary scale of the natural world.