Road surfacing is a process of laying down a surface on a road to make it smoother and more durable. MACADAM, ASPHALT, COBBLESTONE, TARMAC, and TAR are all materials used in road surfacing. MACADAM is a type of road surfacing made from small stones and gravel bound together with TAR. ASPHALT is a mixture of sand, gravel, and bitumen that is heated and applied to the road surface. COBBLESTONE is a type of road surfacing made from large, flat stones laid in a pattern. TARMAC is a type of road surfacing made from a mixture of TAR and aggregate. TAR is a dark, sticky substance made from coal and petroleum that is used as a binding agent in road surfacing.