What karazumi is
Karazumi is masonry laid without mortar or any other binder, the stones held in place by their own weight and by how they interlock.
Because it lets water through, it suits erosion-control dams and revetments. The second check dam in the Jinnosuke valley in Ishikawa Prefecture, built in 1915, is described as one of the earliest works of the Hakusan erosion-control scheme, 13.3 metres long and 5.5 high, laid dry, and finely built at an altitude of 2,100 metres from stone quarried and worked on the spot.
At that height nothing could be carried in. Building without a binder belongs to those conditions.
The Iguchi salt-field culvert in Ehime Prefecture, from the late Edo period, is described as a dry-laid granite structure 12 metres long and 0.9 wide at the top, its battered lower part laid diagonally and its near-vertical upper part in level courses like Nunozumi.
Against mortared work
The opposite method beds the stones in mortar. It is stronger but watertight, which is not always wanted.
Later reinforcement sometimes replaces one with the other. The third dam on the Mannai river in Niigata Prefecture, from about 1922, is described as having had its originally dry-laid body reinforced with mortared masonry in the early Showa period, its span on the right bank unusually long. The record keeps the original method and the present state apart.
The Amanogawa erosion-control dam in Osaka Prefecture, from about 1897, is described as a stone structure of squared blocks laid diagonally at a narrows in the river. How the stones are shaped and how they are arranged are separate questions from whether a binder was used.
On site, look into the joints. Gaps running back into the wall indicate dry work; joints filled with mortar indicate the other. Later repairs sometimes point only the surface, so the record is worth checking as well.
References
- Agency for Cultural Affairs: Registered tangible cultural properties (structures)
- https://www.bunka.go.jp/seisaku/bunkazai/shokai/yukei_kenzobutsu/toroku_yukei.html
- National Cultural Properties Database: Jinnosukedani check dam, 13.3 by 5.5 metres, laid dry
- https://kunishitei.bunka.go.jp/bsys/maindetails/101/00009145
- National Cultural Properties Database: Iguchi salt-field culvert, dry-laid with diagonal coursing below and level coursing above
- https://kunishitei.bunka.go.jp/bsys/maindetails/101/00003152
- National Cultural Properties Database: Mannaigawa third dam, originally dry-laid and later reinforced with mortared masonry
- https://kunishitei.bunka.go.jp/bsys/maindetails/101/00003213
- National Cultural Properties Database: Amanogawa erosion-control dam, squared stone laid diagonally at a narrows
- https://kunishitei.bunka.go.jp/bsys/maindetails/101/00003123
Last verified: 2026.09.10