How Magma Formed Today’s Hagi
About 20,000 years ago, when the Japanese archipelago had begun to resemble its current shape, small volcanoes erupted one after the other on the western tip of Honshū. The topography created by these volcanoes has deeply influenced Hagi’s character, food culture, and townscape.
⚪ Abu Volcano Group
⚪ Aonoyama Volcano Group
⚪ Chōmonkyō Gorge
⚪ Hagi Delta
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7 Tatamigafuchi
Susa Bay
Three million years ago, as the Eurasian continent’s eastern edge broke apart, the Japan Sea grew wider, and magma erupted through the earth’s crust. As the lava hardened, it created the islands of Japan and many underwater volcanoes. It was during this age of geologic activity that the landscape of Susa Bay was born.
⚪ Mishima Island
⚪ Kōyama Gabbro Rock
⚪ Susa Hornfels
⚪ Susa Group
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9 Cape Modoro
Movement from the South
Between 300 and 200 million years ago, sinking tectonic plates created the foundations of the Hagi region. The movement of the plates distributed limestone, chert, and other types of stone across the Kawakami, Fukue, and Atō areas. The Pacific plates moved in a northerly direction, subducting under the continental plates. Seamount coral and seabed sediment pressed against and fused with the continental mass in what is called an accretionary wedge.
⚪ Kanoashi Group (Jurassic wedge)
⚪ Handa Limestone (Permian wedge)
⚪ Abugawa Group (Permian wedge)
⚪ Zōmeki Limestone (Permian wedge)
Large Scale Eruptions of Continental Magma
Approximately 100 million years ago, Japan was still a part of the Asian continent. At this time there was intense volcanic activity around the entire planet. Several kilometers beneath the earth’s surface, superheated magma created widespread and large-scale explosions, causing the crust to crack and move. Within Hagi Geopark, you can still see the calderas and other remnants of volcanic activity that occurred during this time.
⚪ Tamagawa Caldera
⚪ Sasanami Caldera
⚪ Sanyō Zone Granite
⚪ Kanmon Group
