Wark on Tweed Wark on Tweed Wark on Tweed (usually referred to simply as Wark) is a village in the English county of Northumberland. It lies approximately south west of Berwick-upon-Tweed. It is on the south bank of the River Tweed which marks the border between England and Scotland. The ruins of Wark on Tweed Castle, originally an early 12th century motte-and-bailey, lie at the west end of the village. The border between Scotland and England runs down the middle of the River Tweed, however between the villages of Wark and Cornhill the Scottish border comes south of the river to enclose a
River Wye river from Redbrook to Chepstow forms the border between England and Wales. The River Wye forms two Sites of Special Scientific Interest, one covering the Upper Wye ("Gwy Uchaf") above Hay-on-Wye, and one covering the Lower Wye ("Gwy Isaf") downstream to Chepstow. The criteria for inclusion of the river as an SSSI include geology, topography, flora, mammals, invertebrates, fish and birdlife, as the river and its tributaries constitute a large linear ecosystem. The Lower Wye SSSI is itself divided into seven units of assessment set by Natural England, and administrative responsibilities are shared between the county authorities of Powys, Herefordshire,