One day a priest and a geologist were discussing how old the Earth was.
According to the Christian religious scholars, this is a theological question and the answer is around 6000 years if you follow biblical chronology. According to scientists, the age is about 4.54 billion years old.
Now before you yawn and say young earth creationists are dumb (some of them probably are), let's get philosophical for a few moments.
The Philosophical Outlook - Civilization
If a tree falls in the woods and no one is there to hear it, does it make a sound? Depending on your answer, tying the age of the Earth to people may make sense. In other words, the roots of modern civilization go back around 6000 years and before then humans weren't much better off than animals.
If you get offended and think cavemen didn't have it so bad, just reflect on that for a few moments. Paleo-man wasn't a so-cal teenaged princess on a strange diet. The primordial man constantly struggled for survival and couldn't plan activities more than a few days ahead. Time and numbers were practically useless and death was always just around the corner. We can't even imagine what that would be like knowing that anything could take you out at any time and there would be no recourse or repercussions, usually, if something took you out they would steal your things and or eat you.
The Scientific Outlook - Astronomy / Geology
The geologist said the earth is significantly older than the priest. Rather than thinking it from a philosophical angle, she thought of the scientific angle. The early earth was formed around 20 million years after the solar system. It was a hot lump of rocks surrounded by a lot more rocks. It was insanely violent for the first 500 million years or so while water and atmosphere were joining the party. Then boom 4 billion years life and in the last 100 thousand or so years modern humans.
How do we know? Fossils show life, We can look in seaside cliffs to see different strata and compare the fossils we find, carbon dating and other nuclear decay determined from radiographic dating etc. We can look at what we have and rewind the clock. Telling the past from the present is a hell of a lot easier than telling the future.
However, is 4.5 billion years ago going back far enough? Sure the oldest rocks won't be any older. But, the universe is 13.8 billion years ago and matter in its present form was created then. Therefore pieces of stuff (atoms, protons, etc) in the Earth are at least that old. But I would not want to go there because then we can hardly be talking about the Earth.
This is more of a hill than a cliff I guess. It was taken near the yellow sea when I went to visit Korea somewhere near Incheon. I don't think the water actually reaches those rocks unless it is stormy because I see trees.
Who is Right?
The scientists!
Unless you are answering a different question, then the answer depends on the question.
I've always liked to look out at the sea, that's where life began. I also prefer cliffs to beaches if I have no intention of swimming. They tell a better story and offer a better view.
I'm not sure how old this cliff is but some of the rocks in it would be at least older than me.