Why are the Blue Mountains Blue?

Every year people from around the world visit the Blue Mountains, situated just a few miles away from the bustling city of Sydney. These incredible mountains don the blue color and appear one with the sky, creating a breathtaking illusion. As the perfect gateway for a short trip, its popularity never ceases.

Are you curious why the blue mountains are called the blue mountains? Are they really blue? We will answer all your questions regarding the unique Blue Mountains of Australia.

The Formation of the Blue Mountains

The Blue Mountains is the name given to a mountain range located in New South Wales, Australia. The region borders the Great Dividing Range, controlled by the Australian Plate.

The Blue Mountains formed millions of years ago when the entire area was part of a shallow sea. The rivers brought shales, siltstones, and mudstones and later dumped vast amounts of sand in the area, burying the other sedimentary rocks. With time, around a million years ago, residues formed a structure of sandstone and shale, creating a rocky upland. Eventually, the water levels went down, and these hard rocks slowly transformed into mountains with the help of continuous erosion from natural agents. Frequent volcanic eruptions also helped in the formation of these mountains. 

Why do the Blue Mountains look blue?

Blue Mountains In NSW
Blue Mountains In NSW

The Blue Mountains are so named because of the simple reason that they appear blue when viewed from a distance. The blue color of the mountains is a combination of two distinct phenomena which act together and result in the apparent blue haze.

1. Rayleigh scattering

The haze we encounter is actually because of an optical illusion caused by Rayleigh scattering, named after the British physicist Lord Rayleigh who first analyzed it in the 19th century. This phenomenon is the scattering of light caused by smaller particles in relation to the wavelength of light. This results in angular separation of colors, which is also why the sunset appears red, and the sky appears blue to us.

The color change is thus caused by light scattering in the Earth’s atmosphere (Rayleigh scattering).

2. Eucalyptus bushland

Another primary reason behind the blue color is the Eucalyptus bushland on the mountains. Apart from being a significant food source for the Koalas and homes to the native birds, they also secrete oil. This oil benefits humankind as it helps create many medicines and has other health advantages. The abundant eucalyptus trees emit volatile organic compounds (VOCs) in significant quantities. These combine with dust and water vapor to scatter blue and violet wavelengths of the light spectrum, bathing the entire region in its customary blue haze.

These two factors combine to make the Blue mountains appear blue. The Eucalyptus oil droplets released by the trees combine with dust particles and water vapour in the atmosphere and scatter the short blue wavelengths of light. The colour receptors in our eyes receive these scattered rays and perceive the mountain to be blue.

Why are these mountains called the Blue Mountains?

The name “Blue Mountains” comes from the blue haze that tends to settle in these mountains. This haze is most particularly noticeable in the spring and early summer.

One would see these mountains clad in a blue hue from a distance. Thus, its popularity for having a blue halo around it made it famous as the Blue Mountains. Before this, the Governor of New South Wales, Arthur Philip, named it Carmarthen and Lansdowne Hills in 1788.

The History of the Blue Mountains

These majestic highlands hold an immense historical value that paints the story of Australia’s indigenous people. There was a time when these mountains were home to many Aboriginal tribes, mainly Darkinjung, Tharawal, Wiradjuri, Wanaruah, Dharug, and Gundungurra.

They were the original owners of these great Blue Mountains, which they considered their home for generations. Through these mountains, they carried out their trade. Every part of this mountainous region was a part of their soul. Sadly, Aboriginal people drastically decreased after the European settlement in Australia.

Facts about the Blue Mountains

Now, we will discuss some facts about Australia’s best-known natural landmarks, the Blue Mountains.

  • These peaks are spread across 11,400 km² with an altitude of 1,189 m.
  • These mountains are on the edge of Sydney, with their foothills about 50 kilometers west of the Sydney central business district.
  • The Blue Mountains comprises a variety of landscapes like sandstone tablelands, waterfalls, canyons, lush rainforests, valleys, lookouts, etc.
  • The Jenolan Caves are also situated right at the edge of these mountains with dazzling formations and underground rivers.
  • The rocks of these mountains are pretty old, going back to 470 million years ago.
  • The highest peak of the Blue Mountains is One Tree Hill which is 1,112 m.

Visiting the Blue Mountains

If you are planning a trip around Australia or want to get a breather from your hectic life and wish to visit the panoramic beauty of the Blue Mountains, here are some tips.

1. How to reach?

The Blue Mountains are located around 100 kilometers west of Sydney and can be reached by train, bus, and car. The most popular way to get there is through the Blue Mountains Train.

  • The Blue Mountain Train travels from Sydney Central Station up into the mountains and stops at Katoomba, Leura, and Springwood stations.
  • It takes approximately three hours to travel the 80 kilometers between Sydney Central Station and Wentworth Falls Station, with stops at Lithgow, Bathurst, Katoomba, and other towns along the way.
  • Visitors can travel on this train from Sydney Central Station or Katoomba Railway Station if they wish to take in more scenery along the way.

2. Where to Stay 

There are a variety of accommodation venues in the Blue Mountains that will give you the much-needed escape from the stressful hubbub of a city. Whether you want to stay at a quaint and small cabin or get the luxury treatment at a high-end hotel, every option is available.

3. Best Time to Visit

The best time to dwell in these mountains is honestly every month. You don’t have to wait for a particular season to arrive so that you can enjoy the lush magnificence of these highlands. Summers can be relaxed and calming, whereas winter can be cold and mysterious. So, feel free to plan your trip according to your schedule and mood.


We hope we can satisfy your curious mind regarding all the questions you might have concerning these Blue Mountains. We would also recommend you to go ahead and visit the Blue Mountains yourself to understand why the Blue Mountains are so unique.