Revealed in the rocks: Millions of years? or Noah's Flood? Can't be both.

We need to realize that for the first 1,800 years of church history virtually all Christians believed that Noah’s Flood was a global catastrophe. It was not until the early nineteenth century that Christians began to abandon this belief, as deistic and atheistic geologists developed new hypotheses of earth history involving millions of years.

How do we discern the truth?

Flood? or Fiction?