Discover the Biblical Flood that Created Today’s Mediterranean Sea

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Written by Colby Maxwell

Updated: October 11, 2022

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The Mediterranean Sea is one of Europe’s and northern Africa’s most important geological elements, but did you know that it may be a rather recent development? Some scientists estimate that the Mediterranean Sea may have once been a large valley-like land with a thriving animal population. During a geological event, however, the Atlantic Ocean swamped the region and created the body of water we know today as the Mediterranean Sea. Let’s discover the biblical flood that created today’s the Mediterranean Sea!

What is the Zanclean flood?

Discover the Biblical Flood that Created Today's Mediterranean Sea

The Mediterranean Sea was potentially created when the Strait of Gibraltar was eroded, allowing the Atlantic to fill the Mediterranean Basin.


The Zanclean flood is a theory that explains how the modern-day Mediterranean Sea became the body of water it is today.

The Zanclean flood (or Zanclean deluge) is a theory proposed by scientists to explain how the Atlantic Ocean filled the Mediterranean basin. This massive event would have been the start of the Zanclean age and meant the likely extermination of any animals or plant life that happened to be in the region at the time.

Although this theory isn’t totally accepted, it is still regarded as a potential solution to the filling of the basin. In its essence, the theory states that the event was caused by the Strait of Gibraltar’s opening, whether by tectonic subsidence, erosion from a stream, or sea level rise. The most commonly held belief is that a stream slowly eroded the Strait until the Atlantic Ocean finally punched through, allowing the massive region to be filled with water.

Once the Strait was eroded, it is estimated that water from the Atlantic rushed down a drop of 0.6 miles onto the basin floor at a rate of 100 million cubic meters per second, or nearly 1000x the discharge of the Amazon River. Estimations vary, but the rise in water across the basin bay may have occurred at nearly 30 feet a day, taking between a few months and two years to fill totally.

When did the Zanclean flood potentially happen?

The current estimates for when the Zanclean flood occurred place the event around 5.33 million years ago. No humans were alive during that time, although many animals and plants were likely killed during this great deluge. If humans had been around during the catastrophic event, it’s like that many ancient myths would have been created to explain this one-of-a-kind moment. Regardless, there were no ancient humans around during this period, although the last common ancestor between humans and chimpanzees was potentially living during this period.

What were the consequences of the Zanclean flood?

Fastest Water Animals

Many ocean-dwelling animals were able to migrate into the Mediterranean Sea after the Zanclean flood.


Although the Zanclean flood happened before human existence, the regional consequences were still monumental.

Before the flood, animals could cross the basin from Europe into Africa. After the flood, the passageway was effectively cut off, segmenting and isolating the once-transitional region, allowing speciation on either side of the sea. An example of this can be seen in Psammophis odysseus, an ancient species of snake that once lived in Africa and the southern region of Europe. The snake lived around 5.5 million years ago, going extinct in Europe soon after the flood. Its relatives in Africa, however, lived on and continued to evolve.

While the flood stopped some animal migration, it did encourage others, especially in the ocean. When the waters settled, there was a massive new landscape for animal migration into the Mediterranean Sea. Once the water region was established, animals like cetaceans (whales) and pinnipeds (seals) inhabited the area.

Aside from animal migration interference, the flood also changed the resulting region’s weather. Records show that a significantly smaller flood in ancient times triggered a cold period, making it very likely that the massive flood had far-reaching temperature impacts. Estimates show that the potential cooling region reached all the way to modern-day New Caledonia near Australia.

Did animals die during the Zanclean flood?

Things probably weren’t good for any animals in the Mediterranean basin at the time. Due to the amount of water, seismic activity was triggered, causing landslides and tsunamis over 330 feet tall. Additionally, any sea life initially shot into the basin would have been killed as the water was still shallow and mixed with a lot of sediment.

Have other large-scale floods occurred on the Earth?

Discover the Biblical Flood that Created Today's Mediterranean Sea

Lake Bonneville was once the site of the second largest flood in geologic history.

©Robert Stolting/

Although the Zanclean flood is one of the largest, other similar floods have existed throughout history. In North America, the Bonneville flood overflowed through the Snake River Basin near the last ice age, and it is known as the second largest flood in geologic history. The Black Sea deluge hypothesis is similar to the Zanclean flood hypothesis and examines the possibility of the Mediterranean Sea flooding into the Black Sea through the Bosporus Strait.

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About the Author

Colby is a writer at A-Z Animals primarily covering outdoors, unique animal stories, and science news. Colby has been writing about science news and animals for five years and holds a bachelor's degree from SEU. A resident of NYC, you can find him camping, exploring, and telling everyone about what birds he saw at his local birdfeeder.

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