Latitude -33.735225, Longitude 150.31477
Located in the Sydney Surrounds Region of NSW, nearest town Katoomba
The Three Sisters are an icon of the Blue Mountains and daily they attract visitors from around the world to view their intriguing landscape. Because of the jointing patterns of the Hawkesbury Sandstone similar turret-like rock-stands exist throughout the Blue Mountains but none so accessible or impressive as The Three Sisters.
The strong jointing property of Narrabeen sandstone is well demonstrated in the Three Sisters. The sandstone has strong vertical jointing in a grid like pattern and over time erosion widened these joints to leave the vertical turrets of sandstone which form the Three Sisters. The section of sandstone that makes up The Three Sisters also contains many horizontal layers of erosion resistant ironstone that have probably helped the Sisters to resist erosion and stand proud.
In the future, joint widening between the Sisters will endanger them as they become more and more narrow. They will eventually tumble into the valley below.
Many natural landforms in the Blue Mountains have special significance to Aboriginal people. The Three Sisters rock formation is sacred to the Gundungurra people who tell the story of how the sisters were turned to stone by their father, a Witch Doctor, to protect them from a dangerous and much-feared Bunyip.
If you take the Giants Staircase to the base of the cliff-face you will be travelling back in geological time. You can follow the Federal Pass track around the base of the cliffs to the lower terminus of the Scenic Railway. This railway was originally built to carry coal and oil shale up from the Katoomba Coal Mine. At 52° and with a drop of 415 metres it's the steepest railway in the world (Guinness Book of Records), and was originally part of the Katoomba mining tramways constructed between 1878 and 1900. The coal and oil shale mined at the base of the cliff was from the Katoomba Seam of the Illawarra Coal Measures.
Around 300 million years ago huge earth movements caused the earth's crust in the region to subside and the quartzite landscape on which the Blue Mountains stands was flooded by a shallow sea from the east. Streams flowing into this sea carried huge amounts of sediment, which were deposited in horizontal layers. Later, these layers formed rock beds of shales, siltstones and mudstones. In swampy areas around the margins of the sea, piles of dead vegetation were buried under the sediment. They would eventually become seams of coal known as the Illawarra Coal Measures.
The Three Sisters Rock Formations are located at Echo Point, Katoomba in the Blue Mountains. They can be viewed from the lookout at Echo Point which is at the end of Lurline Street. You can examine them close up by walking down the Giants Stairway where there is a bridge leading to the first sister.