The Harz is a low mountain range in the Central Uplands of Germany, famous for its historic silver mines that brought prosperity to the region and to the Electorate of Hanover. It lies between the river Elbe and Weser in the states of Lower Saxony, Saxony-Anhalt and, to a small extent, Thuringia. The range runs for 100 km from northwest to southeast and is 30 km wide. The terraced plateaus are made of limestone, sandstone, and slate and have been cut by many narrow, deep valleys. The two highest peaks in the area are the legendary and mysterious Brocken (1,141 m or 3,743 feet high), just higher than Snowdon , and the Wurmberg (971 m or 3,186 feet high), both of which are made of granite. The higher, northwestern area is known as the Upper Harz (Oberharz) and the lower, southeastern area is the Lower Harz (Unterharz). The highest mountains - around the Brocken - are sometimes called the High Harz (Hochharz).