The state is named after Dutch explorer Abel Tasman, who made the first reported European sighting of the island on 24 November 1642. Tasman named the island "Anthony van Diemen's Land" after his sponsor Anthony van Diemen, the Governor of the Dutch East Indies. The name was later shortened to Van Diemen's Land by the British. It was officially renamed Tasmania in honour of its first European discoverer on 1 January 1856. Tasmania was sometimes referred to as "Dervon", as mentioned in The Jerilderie Letter written by the notorious Australian bushranger Ned Kelly in 1879. The colloquial expression for the state is "Tassie". This name is often used in advertising campaigns, for example by the Bass Strait ferry, Spirit of Tasmania.  History Main article: History of Tasmania  Physical history Main article: Geology of Tasmania Tessellated pavement, a rare rock formation on the Tasman Peninsula It is believed that the island was joined to the mainland of Australia until the end of the last glacial period approximately 10,000 years ago. Much of the island is composed of Jurassic dolerite intrusions (upwellings of magma) through other rock types, sometimes forming large columnar joints. Tasmania has the world's largest areas of dolerite, with many distinctive mountains and cliffs formed from this rock type. The central plateau and the southeast portions of the island are mostly dolerite. Mount Wellington above Hobart is a good example, showing distinct columns known as the Organ Pipes. In the southern midlands as far south as Hobart, the dolerite is underlaid by sandstone and similar sedimentary stones. In the southwest, Precambrian quartzites are formed from very ancient sea sediments and form strikingly sharp ridges and ranges, such as Federation Peak or Frenchmans Cap. In the northeast and east, continental granites can be seen, such as at Freycinet, similar to coastal granites on mainland Australia. In the northwest and west, mineral-rich volcanic rock can be seen at Mount Read near Rosebery, or at Mount Lyell near Queenstown. Also present in the south and northwest is limestone with magnificent caves. The quartzite and dolerite areas in the higher mountains show evidence of glaciation, and much of Australia's glaciated landscape is found on the Central Plateau and the Southwest. Cradle Mountain, another dolerite peak, for example, was a Nunatak. The combination of these different rock types offers incredible scenery, much of it distinct from any other region of the world. In the far south-west corner of the state, the geology is almost completely quartzite, which gives the mountains the false impression of having snow capped peaks year round.  Tasmania is an Australian island and state. It is 240 kilometres (150 mi) south of the continent, separated by Bass Strait. The state includes the island of Tasmania -- the 26th largest island in the world -- and the surrounding islands. The state has a population of 500,000 (as of December 2008[update]), of whom almost half reside in the greater Hobart precinct. Tasmania's area is 68,401 square kilometres (26,410 sq mi), of which the main island covers 62,409 square kilometres (24,096 sq mi). Tasmania is promoted as the natural state, the "island of inspiration", and A World Apart, Not A World Away owing to its large and relatively unspoiled natural environment. Almost 37% of Tasmania lies in reserves, national parks and World Heritage Sites. The island is 364 kilometres (226 mi) long from northernmost to southernmost points, and 306 kilometres (190 mi) from west to east. The state capital and largest city is Hobart, which encompasses the local government areas of City of Hobart, City of Glenorchy, and City of Clarence, while the satellite town of Kingston (part of the Municipality of Kingborough) is generally included in the Greater Hobart area. Other major population centres include Launceston in the north and Devonport and Burnie in the northwest. The subantarctic Macquarie Island is also under the administration of the state, as part of the Huon Valley Council local government area.