Harris (Scottish Gaelic: Na Hearadh) divides naturally into northern and southern parts which are separated by West and East Loch Tarbert. These halves are joined by a narrow isthmus at the main settlement of Tarbert (Scottish Gaelic: An Tairbeart). North Harris consists of imposing peaks and a rugged landscape formed from some of the oldest rocks on the planet, which provide a striking contrast to the low-lying moors of Lewis. The dark, jagged peaks of North Harris give way to a more gentle landscape in South Harris, with brilliant white shell beaches, crystal clear waters and a stunning backdrop of machair, which in the summer months comes alive with wildflowers, butterflies and birds. Scalpay (Scottish Gaelic: Sgalpaigh) is a small island connected to Harris via a single track bridge, built in 1997. Eilean Glas, on a small peninsula to the eastern shore of the island, is home to the first lighthouse built in the Outer Hebrides.