Black Mountain (Kalkajaka) National Park is a protected area in the Queensland, (Australia), 25 km south west of Cooktown. The main feature of the park is the mass of granite boulders, some the size of houses.
The absence of soil between the boulders and rocks create a maze of gaps and passages, which can be used to penetrate inside the mountain. These rocks can become extremely hot. The area has a bad reputation as numerous people and those searching for the missing have disappeared without trace.
The national park's distinctive hard granite boulders and range originally formed out of magma that first slowly solidified under the Earth's crust about 250 million years ago. The softer land surfaces above the solidified magma eroded away over time, leaving the magma's fractured top to be exposed as a mountain of grey granite boulders blackened by a film of microscopic blue-green algae growing on the exposed surfaces. Colder rains falling on the dark, heated granite boulders causes the boulders to progressively fracture, break, and slowly disintegrate, sometimes explosively.
The National Park's "Black Mountains" are a heavily significant feature of the Kuku Nyungkal people's cultural landscape known locally to Aboriginal Australians as Kalkajaka (trans: "place of spear").
There are at least four sites of religious or mythological significance on the mountain. These are the Kambi, a large rock with a cave where flying-foxes are found; Julbanu, a big grey kangaroo-shaped rock looking toward Cooktown; Birmba, a stone facing toward Helenvale where sulphur-crested cockatoos are seen; and a taboo place called Yirrmbal near the foot of the range.
Stories abound of people, horses and whole mobs of cattle disappearing into the labyrinth of rocks, never to be seen again It is believed that those who vanished most probably fell into one of the chasms under the rocks or after entering one of these places became lost.
The discussion of mysterious features of the Black Mountain featured in an episode of the Ancient Aliens television series on the History Channel. The series claimed that the hills of the Kalkajaka could have been formed by ancient astronauts who piled the huge boulders to cover up a massive mining operation, or, alternatively, that the boulders were debris formed as a result of the mining operation.