Referring Clues

• A lot of time
• Many millennia
• Billions of years
• Years and years
• Geologic periods
• Almost forever
• A dog's age
• Seemingly forever
• Incalculable amount of time
• Ages and ages
• Time and time again
• Astronomical figures
• Years on end
• Many ages
• Astronomical periods
• Stretch of history
• A lo-o-ong time
• Donkey's years
• A long time to wait
• Billions of years, geologically
• Spans of history
• Millions of years
• An eternity, seemingly
• Time on end
• Seeming eternity
• Long stretches
• Long periods
• Forever and a day
• Time immemorial
• An extremely long time
• Awfully long time
• A long, long time
• Great times
• Lengthy time units
• Eternities
• Major stretches
• Stretches of history
• Long times
• Years and years and years
• How long it takes canyons to form
• Some collars and jackets
• A seeming eternity
• Millennia
• Forever, so to speak
• Units of geologic time
• Geological periods
• Forever, it seems
• Long periods of time
• Millennia upon millennia
• Mind-boggling time spans
• Forever, seemingly
• Interminable length of time
• Long periods, geologically
• Almost eternity
• Almost eternities
• Many, many moons
• Multiple millennia
• Geological time periods
• Billions and billions of years
• At least two billion years
• Centuries of centuries
• Units on the geologic time scale
• Long, long times
• Really long times
• Evolutionary time periods
• Geologic timespans
• Almost an eternity
• Geologic spans
• Long, long time
• Tons of time
• Hundreds of centuries
• Geologic divisions
• Geologic time divisions
• They last a long time
• Astronomical time periods
• Mammoth time units
• Big times
• Ages
• Loooong time
• Zillions of years
• Many many centuries
• Forever and ever
• A looooong time
• Major time periods
• Very long time
• Extra-long durations
• Very long times
• Immeasurable periods
• Very long stretches
• Lengthy units of time
• Stellar periods
• Extremely long time
• Unfathomable stretches
• One billion years, geologically
• Billion-year increments, in geology
• Many, many millennia
• Practically forever
• Countless centuries
• A billion years, geologically
• Units of time
• Incalculable amounts of time
• Untold centuries
• Indefinitely long periods of time
• Geologists' times
• Countless ages
• Extremely long time frames
• Ages and ages and ages
• Extremely long stretches
• Immeasurably long periods of time
• They seem to last forever
• Time divisions
• An eternity
• Billion-year increments
• Forever, figuratively
• Years upon years
• Really long time
• Ages upon ages
• Extremely long time periods
• Quite a while
• A very long time
• Geologic stretches
• Geologic time spans
• Gobs of time
• Billion-year periods
• For-EV-er
• Geologic time periods
• Unimaginably long stretches
• Many, many years
• Geologic procession
• Time beyond measure
• Cosmic cycles
• Ages on end
• A long time
• Long time
• Many lifetimes
• Forever
• Earth's age, perhaps
• Eternities, seemingly
• Long, long time spans
• Thousands of centuries
• Gazillions of years
• Very long spans
• Geologists' periods
• Vast ages
• A really long time
• Long geologic stretches
• Vast stretches of time
• Eternity
• Many years
• Quite a long time
• Lotsa time
• Oodles of time
• Kajillions of years
• Nigh-infinite periods
• Near-infinite timespans
• Time to evolve?
• Just about forever
• Nearly forever
• Quite some time
• How long it takes mountains to form
• Geologic times
• Many centuries
• Immense time spans
• A long, long, long time
• Huge amount of 50-Across
• Vast periods
• Long, long stretches
• Not just centuries
• Basically forever
• Tremendous spans
• Millennia on end
• Countless years
• Ages upon ages of time
• Centuries
• Geology class periods [subscribe to the best indie xwords today at avxwords.com]
• A lot of the time?
• Eras upon eras
• Infinity
• Mountains have developed over them
• I-don't-know-how-long
• Forever, basically
• Inconceivably long times
• Thousands of years
• See 37-Down
• Long spans
• A metaphorical eternity
• "Like, forever"
• Incredibly long time
• Essentially forever
• Thousands and thousands of years
• Mountains form over them
• Geological timespans
• Time since the Big Bang
• Billion-year stretches
• Geological units
• Mountains have grown over them
• Life span of a star
• Huge spans
• What mountains rise over
• Cosmic periods
• Stars exist over them
• Spirits
• Very long periods
• Immense spans
• Almost-endless ages
• Geological eras
• Peaks form over them
• Immeasurable time
• Spans of many centuries
• Not quite eternity
• Innumerable years
• Mind-boggling spans
• Earth science measures
• Volcanoes develop over them
• Vast time periods
• Millions and millions of years
• Extremely long time divisions
• Very long time periods
• Long stretch
• Long times to wait
• They're longer than 57-down
• A kazillion years, it seems
• Long time to wait
• Eras
• Ages galore
• Many, many ages
• Many millenia
• Divisions of geological time
• Endless periods
• Long times in the onslaught
• Unbearable waits
• Long time periods
• Unimaginably long time
• Who-knows-how-long
• Mountains formed over them
• Hyperbolic stretches of time
• One's lost for ages
• Layers of the Onion on repeat for long periods
• Many moons
• Astronomer's measures
• Lots of time with broken nose?
• Eternity, so to speak
• Massive time periods
• Life spans of suns
• Centuries upon centuries
• Astronomical spans
• They go to great lengths
• Quite a stretch
• Practical eternity
• See 19 across
• Periods of two or more of 40-Across
• Immensely long stretches
• Geologic ages
• Billion-year time divisions
• Gorges are carved over them
• Many, many, many, many, many moons
• Truly, a serious wait
• Practically an eternity
• Considerable stretches
• Interminable times
• Long timespans
• Extensive periods
• The Hadean, the Archean and the Proterozoic, e.g.
• **Ages and ages (2 and 3)
• Earth's longest time divisions, geologically
• Extremely long times
• Very long stretches of time
• Geologic time frames
• Very long time spans
• Extreme stretches
• Long runs?
• Many, many, many moons
• Forever and a day, say
• Periods longer than eras
• Long stretches of time
• Time pieces
• Astronomically long time periods
• Long time spans
• Geological spans
• Galactic time spans
• Very, very long time periods