Each year there is an increment of living bark that results in the continual expanding girth of the tree. In all species [of eucalyptus] the outermost layer dies each year. In about half of the species this dead layer completely sheds, exposing a new layer of living bark, and the process continues year after year. Source.Perhaps there is a message for us, for me, in this. There is beauty to be found amidst the messiness of change and growth.