群馬県甘楽郡下仁田町・藤岡市境界の白髪岩における 原三角測点標石の学術総合調査

The stone markers of "Gen-sankakusokuten", the Original Triangulation Point, installed during the "National Triangulation Project" in the early Meiji era are confirmed to exist only at the summits of Mt. Kumotoriyama, Mt. Yoneyama, and Mt. Shiragaiwa. In this study, we describe and compare the condition, form, inscriptions, and the rock material of the Original Triangulation Point stone markers installed near the summit of Mt. Shiragaiwa and Mt. Yoneyama. Additionally, vegetation and geological surveys near Shiragaiwa were conducted, revealing the presence of Sasa nipponica growing on the forest floor with the mudstone mixed-rock basement with gently sloping or flat surfaces, along with chert blocks where azaleas naturally grow. Based on petrographical observations of the stone makers in Shiragaiwa, it was determined that they are made of dacite. A comparison with other Meiji-period small shrines made of locally exposed dacite, the Kunugiishi stone, was conducted, leading to the conclusion that the Shiragaiwa marker is made of the Kunugiishi stone. The transportation route of the Shiragaiwa marker, made from the Kunugiishi stone produced in Nanmoku village, transported via Shimonita to Shiragaiwa, was estimated. Comparing the shapes of fonts and font sizes based on rubbings from the sides of the markers, it was found that the distinctive fonts on the Shiragaiwa and Yoneyama markers are common except their installation years and months, suggesting that they were inscribed based on the model brushed by the same person. Since the Original Triangulation Point marker at Shiragaiwa was not inherited during the later establishment of the first order triangulation stations, it is highly likely that it remains in its original location. [ABSTRACT FROM AUTHOR]