This is why they are called 'The Blue Mountains'

We visited the Mt Tomah Botanic Gardens on the way home from the Central West today. This shot was taken from the cafe looking across the Blue Mountains.

The Blue Mountains, famed for being home to endless eucalyptus (gum tree) forests. High temperatures cause these gum trees to emit a fine mist discharge created from the eucalyptus oil from its leaves. This oil mist then combines with dust particles and water vapour as it rises to surround the area giving it an overall blue tint, especially when the sun shines high and bright. Thus, when viewed from a distance the Blue Mountains look very blue indeed!