3:45 PM - 4:00 PM
[MZZ41-08] Changes in Stone Use from the Edo to Meiji Periods: Examples of Coastal Facilities in Yokosuka, Tokyo Bay
Keywords:Stone Wall, Lighthouse, Cannon Batterry, Volcanic Rock, Tuff
Tokyo Bay, the political center from Edo age, was an important location for shipping and national defense before aircraft became important military tactics, and various historical facilities made of stone were built along the coast. Because strong winds carrying salty seawater blow along the coast, some of the stone has been salt-weathered, but tree growth is kept under control and there has been little damage from root overgrowth. This presentation is an excerpt, but it compares the stone use in representative facilities from each period and discusses the changes that have taken place.
・Edo period(details unknown): Foundation stone wall of Uraga Tomyodo(Historic site of Yokosuka City)
Volcanic rock is cut and joined similarly to the stone wall of Edo Castle, and the corner stones are made of “sangi-tsumi“ method. The volcanic rock looks like lava from Manazuru Cape in Kanagawa Prefecture, but there is no uniformity in the color tone. It is a small structure with a height of 1.8m, but has a warp, also known as a ”ogi-no-kobai” fan slope. The specific year of construction is unknown, but the salt weathering of the stone varies, so it is thought to have been repaired several times due to earthquakes, etc. In the Meiji period, Western-style lighthouses were built, but the base of Mikomoto-jima Island Lighthouse, the oldest surviving government lighthouse (completed in 1870) (from the Agency for Cultural Affairs website), is made of 4- to 6-sided stone masonry of tuff from the Shirahama Group using cement, but “ogi-no-kobai” fan slope remains.
・1884: Stone wall of Sarushima Island Battery(nationally designated historic site)
Bricks are used, but no cement is used in bluff-style stonework. Boshu-ishi Stone from Nokogiri-yama mountain in Chiba Prefecture is often used for bluff-laid stonework, but there are multiple rock types, and stone from rock types different from Boso stone is clearly used. Volcanic rock is used for the stone steps and keystones for the windows. The bluff-laid stonework in the section built in 1897 is vertical and not warped.
・1886 (Meiji 19): Stone wall of Hashirimizu Battery
The area around the cannon base is made of English-style tuff stone walls, with vertical cement-laid masonry. The tuff appears to be of one type in terms of lithology, and is most likely Boshu-ishi Stone. Volcanic rock is used for the stone steps. The outer revetment on the coast is made up of parts of volcanic rock and parts of tuff. The tuff used is a stone similar to the scoria tuff of the Misaki Formation.
・1886: Stone wall of Chiyogasaki Battery, Yokosuka City, Kanagawa Prefecture(Nationally designated historic site)
This is a bluff-built tuff stone wall, with vertical cement-laid stonework. The Manazuru Town History(Manazuru Town, 1995) records that Tsuchiya Daijiro, a stone merchant from Manazuru Iwamura, delivered Boso stone. Volcanic rock is used for the stone steps and windows, but it is highly likely to be Manazuru Cape lava, based on the remains of a quarry on the coast of Manazuru that was uplifted by the Great Kanto Earthquake of 1923 (Kasama, 2024). It is also noteworthy that granite is used for the road surface. Tsuchiya Daijiro moved his business base from the volcanic rock around Manazuru to the granite of Inada, Ibaraki Prefecture. Looking at the above trends, we can see a shift from using volcanic rocks that were fitted together on site to using regular shaped tuff, and the origin of the stones was concentrated in Chiba Prefecture. We can also see a trend in which the stone walls were initially curved but then became straighter.
In summary, the use of volcanic rock that was matched on site changed to the use of standard tuff, and the source of the stone changed to Boshu-ishi Stone only. Also, the stone wall was initially curved, but now it is vertical.
Agency for Cultural Affairs website
https://www.bunka.go.jp/kindai/todai/069/index.html
Tomohiro Kasama, 2024: Relationship between the Banbaura Coast Quarry Site and the Coastal Uplift Caused by the Great Kanto Earthquake. 2024 Meeting of the Geological Society of Japan, T4-O-2.
・Edo period(details unknown): Foundation stone wall of Uraga Tomyodo(Historic site of Yokosuka City)
Volcanic rock is cut and joined similarly to the stone wall of Edo Castle, and the corner stones are made of “sangi-tsumi“ method. The volcanic rock looks like lava from Manazuru Cape in Kanagawa Prefecture, but there is no uniformity in the color tone. It is a small structure with a height of 1.8m, but has a warp, also known as a ”ogi-no-kobai” fan slope. The specific year of construction is unknown, but the salt weathering of the stone varies, so it is thought to have been repaired several times due to earthquakes, etc. In the Meiji period, Western-style lighthouses were built, but the base of Mikomoto-jima Island Lighthouse, the oldest surviving government lighthouse (completed in 1870) (from the Agency for Cultural Affairs website), is made of 4- to 6-sided stone masonry of tuff from the Shirahama Group using cement, but “ogi-no-kobai” fan slope remains.
・1884: Stone wall of Sarushima Island Battery(nationally designated historic site)
Bricks are used, but no cement is used in bluff-style stonework. Boshu-ishi Stone from Nokogiri-yama mountain in Chiba Prefecture is often used for bluff-laid stonework, but there are multiple rock types, and stone from rock types different from Boso stone is clearly used. Volcanic rock is used for the stone steps and keystones for the windows. The bluff-laid stonework in the section built in 1897 is vertical and not warped.
・1886 (Meiji 19): Stone wall of Hashirimizu Battery
The area around the cannon base is made of English-style tuff stone walls, with vertical cement-laid masonry. The tuff appears to be of one type in terms of lithology, and is most likely Boshu-ishi Stone. Volcanic rock is used for the stone steps. The outer revetment on the coast is made up of parts of volcanic rock and parts of tuff. The tuff used is a stone similar to the scoria tuff of the Misaki Formation.
・1886: Stone wall of Chiyogasaki Battery, Yokosuka City, Kanagawa Prefecture(Nationally designated historic site)
This is a bluff-built tuff stone wall, with vertical cement-laid stonework. The Manazuru Town History(Manazuru Town, 1995) records that Tsuchiya Daijiro, a stone merchant from Manazuru Iwamura, delivered Boso stone. Volcanic rock is used for the stone steps and windows, but it is highly likely to be Manazuru Cape lava, based on the remains of a quarry on the coast of Manazuru that was uplifted by the Great Kanto Earthquake of 1923 (Kasama, 2024). It is also noteworthy that granite is used for the road surface. Tsuchiya Daijiro moved his business base from the volcanic rock around Manazuru to the granite of Inada, Ibaraki Prefecture. Looking at the above trends, we can see a shift from using volcanic rocks that were fitted together on site to using regular shaped tuff, and the origin of the stones was concentrated in Chiba Prefecture. We can also see a trend in which the stone walls were initially curved but then became straighter.
In summary, the use of volcanic rock that was matched on site changed to the use of standard tuff, and the source of the stone changed to Boshu-ishi Stone only. Also, the stone wall was initially curved, but now it is vertical.
Agency for Cultural Affairs website
https://www.bunka.go.jp/kindai/todai/069/index.html
Tomohiro Kasama, 2024: Relationship between the Banbaura Coast Quarry Site and the Coastal Uplift Caused by the Great Kanto Earthquake. 2024 Meeting of the Geological Society of Japan, T4-O-2.