What Science Says
Like Creation, Noah’s flood can be a highly emotive topic for Christians. There are those who insist it is and must be literally true in every detail and others who would prefer to say that some sort of flood occurred but some details could be interpreted differently. Bitter arguments can quickly arise and division occur over this part of Scripture.
This is an area that science can comment on. Because it describes an historic flood of potentially global scale, there should be evidence in the geological record of what happened. Enough is known of the consequences and hallmarks of floods that it is possible to postulate what evidence a global flood would have left behind. We can then look to see if such evidence exists.
When a flood occurs, particularly one of the extent and catastrophic nature of the flood described in Genesis, rocks become broken up and are carried away from their original place. As the flood subsides these rocks are dropped into new resting places, creating a layer of broken-up rock. It would be clear from the type of rock that they had not formed in their current position, but had formed elsewhere and then be carried to their current position by water.
In floods of high-energy and a catastrophic nature, a lot of material is carried of varying nature and size. When the water loses its energy the material would be dropped together, creating a deposit of rocks that are very mixed in their size. In other places, energy would be lost from the water slowly. In these situations the largest rocks are dropped first, and as more energy is gradually lost increasingly smaller rocks are deposited. This creates a layered deposit with the largest rocks at the bottom and the smallest at the top.
The flow of the water causes rocks from very different areas to all be mixed together. The water will carry plant and animal matter along with it. When these are deposited, there will be plants and animals dropped together that are not usually found in the same place. There may be land animals deposited in the sea; animals from mountains found with animals from plains; those from forests found with those from deserts.
Carbon dating would reveal that these unusual deposits occurred somewhere in the last 10 000 years (depending on your belief of when the flood occurred). Some of the deposits on land would have unusually high salinity. Whilst some land deposits might have been eroded, the sea bed should show a continuous layer of unusual deposits in which organisms normally living on land are found mixed with the deposits of those that live in the sea.
None of these features are present in the geological record. In particular, the sea bed shows no evidence of a global flood of such size that everything, except Noah and those with him, died. There are no deposits in which animals and plants from a variety of places are found together, and neither are there any high salinity deposits.
Most strikingly, no lakes show evidence of a global flood. Lakes have characteristic deposits, as the amount of matter that is deposited and the rate at which it is deposited varies with season. These clear annual cycles in some of our well-studied lakes clearly stretch back for over 10 000 years with no interruption by a catastrophic flood. Floods have occurred, but they are regional floods such that a year in which a flood occurred in one lake is not matched by evidence of a flood in the same year in another lake.
There is thus no evidence that there was a flood that covered the entire earth.
Without such evidence, some have postulated that the entirety of the sedimentary rock sequence worldwide is the result of Noah’s flood. But this theory has many problems. Coral reefs live in shallow water, gradually growing upwards. Fossil coral reefs would not have formed over a few months in the turbulent seas of a global flood. Swamps show multiple generations of channels that also would have taken years, not months, to form.
The Grand Canyon has been cited as a feature carved out by global flood waters. But the features of the Coconino Sandstone, a rock formation in the Canyon, show that it was formed by the sustained action of wind in an arid environment. The rounded sand grains and steep sides are inconsistent with the jagged shape and shallow slopes that water would create.
A worldwide flood that wiped out all humans except Noah and his family would show a cessation in human activity across the globe, at the same period of time. There would then be a gradual return of human activity, starting in the region of Noah and spreading outwards as humans recolonized the earth. There is no such cessation and recolonisation pattern in the global record.
There is evidence of regional flood in the Mesopotamian basin, where Noah lived. These floods were catastrophic for the local population.
Other historical evidence would appear as oral traditions of catastrophic floods. We have the Genesis account, and also the Greek Deucalion myth and the Sumerian Ziusudra tradition which are from the nearby territories. Other flood stories come from across the world, but these bear less resemblance to the Genesis account.
The science therefore tells us that there was not a global flood.