The Earth was flooded for about a year, including the 40 days of rain. Sediments were deposited which were later eroded, metamorphosed and lithified as the waters subsided.
A Tribulation Anoxic Event
The Cenomanian-Turonian anoxic event may have an analogue in prophecy. So what does the scripture say? Is there any evidence that an anoxic mass-extinction event is recorded in the Bible?
The Theory of Noah’s Flood
We have a collection of predictive testable hypotheses which authenticate physical evidence of Noah's flood with the account in scripture. In science a collection of hypotheses which support a premise is called a theory.
Our prediction is that there was a mass extinction of marine life during Noah's flood. The test is the stratigraphic evidence of a world-wide anoxic extinction. That's a scientific hypothesis.
A World-wide Anoxic Event
Anoxic means without Oxygen. All around the world we see contemporaneous evidence of a mass extinction of marine life caused by the depletion of oxygen in the water.
Iridium abundance maxima in the Upper Cenomanian extinction interval
Two iridium abundance peaks, both 0.11 ppb (whole‐rock basis) over local background of 0.017 ppb, have been found in Middle Cretaceous marine rocks near Pueblo, Colorado.
A world-wide anoxic extinction event above the Cretaceous/Tertiary boundary is a logical outcome of the worlds ecosystems decomposing in the waters of Noah's flood.
A world-wide anoxic extinction event above the Cretaceous/Tertiary boundary is a logical outcome if the worlds ecosystems were decomposing in the waters of a year-long world-wide flood.