
Thomas Telford, the Scottish road and bridge builder, knew enough about rocks to recommend that particularly hard basalt, locally known as dhu stone, which was found on the top of the Clee Hills in Shropshire would make a hard wearing and long lasting road material. The problem...

Thomas Telford, the Scottish road and bridge builder, knew enough about rocks to recommend that particularly hard basalt, locally known as dhu stone, which was found on the top of the Clee Hills in Shropshire would make a hard wearing and long lasting road material. The problem...