If sediments have been accumulating on the seafloor for three billion years, the seafloor should be choked with sediments many miles deep.
Every year water and wind erode about 20 billion tons of dirt and rock debris from the continents and deposit them on the seafloor.1 (Figure 1). Most of this material accumulates as loose sediments near the continents. Yet the average thickness of all these sediments globally over the whole seafloor is not even 1,300 feet (400 m).2
Some sediments appear to be removed as tectonic plates slide slowly (an inch or two per year) beneath continents. An estimated 1 billion tons of sediments are removed this way each year.3 The net gain is thus 19 billion tons per year. At this rate, 1,300 feet of sediment would accumulate in less than 12 million years, not billions of years.
This evidence makes sense within the context of the Genesis Flood cataclysm, not the idea of slow and gradual geologic evolution. In the latter stages of the year-long global Flood, water swiftly drained off the emerging land, dumping its sediment-chocked loads offshore. Thus most seafloor sediments accumulated rapidly about 4,300 years ago.4
Those who advocate an old earth insist that the seafloor sediments must have accumulated at a much slower rate in the past. But this rescuing device doesn’t “stack up”! Like the sediment layers on the continents, the sediments on the continental shelves and margins (the majority of the seafloor sediments) have features that unequivocally indicate they were deposited much faster than today’s rates. For example, the layering and patterns of various grain sizes in these sediments are the same as those produced by undersea landslides, when dense debris-laden currents (called turbidity currents) flow rapidly across the continental shelves and the sediments then settle in thick layers over vast areas. An additional problem for the old-earth view is that no evidence exists of much sediment being subducted and mixed into the mantle.