Possible Clues:

• Part of upper atmosphere
• Sunblock that's nearly ooze when spread
• Australia has a single chicken and it's fast disappearing
• Protective belt's better on old patch
• Harmful rays absorbed here nearly ooze out
• Covering with a 'hole' in it
• Part of upper atmosphere that is gradually disappearing
• Old sector produced early form of protection from the sun
• It's found all around the world
• Chlorofluorocarbons damage it