The next day, wonderfully, dawned fine, hot and blue.
The Blue Mountains are the eroded remains of a mostly sandstone plateau, with talus slopes falling away at the bottom of the steep cliffs. Walkways run around and often just below the tops of the cliffs, and I am afraid that one of my lasting memories of walking in the Blue Mountains will be of lots and lots of stairs...
The blue colour of the distant mountains reputedly due to Rayleigh scattering off eucalyptus oil aerosol evaporated from the vegetation, which leads to there being explanations of this physical phenomenon in all the tourist brochures.
Because of yesterday's rain the valleys are ringing with the sound of falling water and with what I assume is frog-song. It's a very pretty sound.