Related Clues:

• Archeozoic, e.g.
• Depression, for one
• 1970's-80's cause, for short
• Gay 90's, e.g.
• Center of an apple
• Apple's leftover
• History text topic
• It may have periods
• Feminist pitcher's concern?
• Fundamental
• Geological time
• Geologist's time division
• Oft-nicknamed period
• Geological period
• Important time