Cape York is the northernmost point on the Australian continent. It was named by Lieutenant James Cook on 21 August, 1770, after Prince Edward, Duke of York and Albany. The Duke was a brother of King George III of the United Kingdom, and died from illness in 1767 when he was only 20 years old:
The tropical landscapes are among the most stable in the world. There has been no tectonic activity for millions of years. The peninsula is an extremely eroded, almost level, low plain with mighty meandering rivers and vast floodplains. There are some very low hills, about 800m above sea level in the McIlwraith Range on the eastern side around Coen.
Part of Australia’s Great Dividing Range, the Peninsula Ridge, is like a backbone along the peninsula. This mountain range is made up of ancient (1,500 million year-old) Precambrian and Palaeozoic rocks. To the east and west of the Peninsula Ridge lie the Carpentaria and Laura Basins, themselves made up of ancient Mesozoic sediments. There are several important landforms on the peninsula: the large area of undisturbed sand dunes on the east coast around Shelburne Bay and Cape Bedford-Cape Flattery; the huge piles of black granite boulders at Black Mountain National Park and Cape Melville; and the limestone karsts around Palmerston in the south.
The soils are poor, even compared to other areas of Australia. They are ancient and weathered, not suitable for ploughing and do not respond to fertilizers. Because of the poor soil, the region is thinly settled. Attempts to grow commercial crops have usually failed.
The climate on Cape York Peninsula is tropical and monsoonal. The heavy monsoon season is from November to April, during which time the forest becomes almost inhabitable. The dry season is from May to October. The temperature is warm to hot, with a cooler climate in higher areas. The mean annual temperatures range from 18 °C at higher elevations to 27 °C on the lowlands in the drier southwest. Temperatures over 40 °C and below 5 °C are rare.
Annual rainfall is high, ranging from over 2000 mm. in the Iron Range and north of Weipa to about 700 mm. at the southern border. Most of this rain falls between November and April. Only on the eastern slopes of the Iron Range is the median rainfall between June and September above 5mm (0.2 inches). Between January and March, however, the median monthly rainfall ranges from about 170mm (6.5 inches) in the south to over 500mm (20 inches) in the north and on the Iron Range.
The Peninsula Ridge forms the drainage divide between the Gulf of Carpentaria and the Coral Sea. To the west, large, winding river systems including the Mitchell, Coleman, Holroyd, Archer, Watson, Wenlock, Ducie and Jardine flow into the Gulf of Carpentaria. During the Dry season, those rivers become a series of waterholes and sandy beds. Yet, with the heavy rains in the Wet season, they become mighty waterways, spreading across huge floodplains and coastal wetlands and giving life to many freshwater and wetland species.
On the Eastern slopes, the shorter, faster-flowing Jacky Jacky Creek, Olive, Pascoe, Lockhart, Stewart, Jeannie and Endeavour Rivers flow towards the Coral Sea. These provide important freshwater and nutrients to the healthiest section of the Great Barrier Reef. Along their banks, those wild, undisturbed rivers are lined with dense rainforests, sand dunes or mangroves.
The floodplains of the Laura Basin are now protected in the Lakefield and Jack River National Parks. The plains are crossed by the Morehead, Hann, North Kennedy, Laura, Jack and Normanby Rivers.
The Peninsula’s rivers are famous for their hydrological integrity. This means that they are still in their natural state, with water flows and vegetation unchanged. Cape York Peninsula is one of the few places where tropical water cycles remain unchanged. Cape York Peninsula has as much as a quarter of Australia's surface runoff. With less than 3% of Australia's land area it produces more run-off than all of Australia south of the Tropic of Capricorn. The peninsula’s rivers are also important as they put water back into central Australia’s Great Artesian Basin. The Queensland Government is planning to protect 13 of Cape York Peninsula’s wild rivers under the Wild Rivers Act 2005.
Around 40 million years ago, the Indo-Australian tectonic plate began to split apart from the ancient supercontinent Gondwana. As it crashed into the Pacific Plate on its northward journey, the high mountain ranges of central New Guinea were made around 5 million years ago. Protected from this collision zone, the ancient rocks of what is now Cape York Peninsula were did not move.
During the Pleistocene epoch Australia and New Guinea have been land-linked and separated by water a number of times. During the ice ages with their low sea levels, Cape York Peninsula was a low-lying land bridge. Another link existed between Arnhem Land and New Guinea, at times making a big freshwater lake, Lake Carpentaria, in the centre of what is now the Gulf of Carpentaria. In this way, Australia and New Guinea were joined until the shallow Torres Strait was last flooded around 8,000 years ago.
Cape York Peninsula has a range of intact tropical rainforests, tropical and subtropical grasslands, savannahs, and shrublands, tropical savannahs, heath lands, wetlands, wild rivers and mangrove swamps. These are home to about 3300 species of flowering plants. Almost all of the Cape York Peninsula (99.6%) still has its native vegetation. Cape York Peninsula also contains one of the highest rates of endemism in Australia, with more than 260 endemic plant species found so far. Because of this, parts of the Peninsula have been noted for their very high wilderness quality. The plants of the peninsula includes original Gondwanan species, plants that have developed since the breakup of Gondwana and species from Indo-Malaya and from across the Torres Strait in New Guinea. Most variety is in the rainforest areas. Most of the Cape York Peninsula is drier than New Guinea which stops the rainforest plants of that island from moving across to Australia.
Most of the Cape York Peninsula is covered in grass and woodlands. These have a tall, thick grass layer and scattered trees, mostly eucalypts. The most common tree is the Darwin stringybark. Although common and complete on the peninsula, tropical savannahs are now rare and in poor condition in other parts of the world.
Tropical rainforests cover an area of 748,000 ha, or 5.6 percent of the total land area of Cape York Peninsula. Rainforests need some rainfall during the long Dry season. These conditions are mostly on the eastern slopes of the Cape’s coastal ranges. These are old-growth forests and support a huge range of plants. These rainforests are of high conservation significance. The largest rainforest area on the Cape is in the McIllwraith Range-Iron Range area. The Gondwanan plants of this area includes Araucariaceae and Podocarpaceae conifers and Arthrochilus, Corybas, and Calochilus orchids. This rainforest has at least 1000 different plants, including 100 rare or threatened species, and 16% of Australia's orchid species.
On poor, dry soils there are tropical heathlands. Northeast Cape York Peninsula has Australia’s largest areas of this highly diverse ecosystem.
The big wetlands on Cape York Peninsula are “among the largest, richest and most diverse in Australia”. 19 wetlands of national significance have been identified, mostly on the large floodplains and in coastal areas. Important wetlands include the Jardine River National Park, Lakefield National Park and the estuaries of the great rivers of the western plains. Many of these wetland only happen during the Wet season and have rare or uncommon plant types.
The Peninsula’s coastal areas and river estuaries are lined with mangrove forests of kwila and other trees. Australia’s largest mangrove forest is at Newcastle Bay.