A double stone wall.
Typically the walls are constructed about a meter apart at the base, leaning slightly towards each other, the core consisting of hard-packed earth. The top is often covered with flagstone. A double stone wall is used as a stone fence around a homesite yard, as a reinforced retaining wall for a pond field bordering a runoff canal to prevent water from flooding into the field and breaking down the retaining wall, or as a wall at the source of an irrigation canal to divert water into the canal.