Cape Verde Boulders Indicate Massive Tsunami 73,000 Years Ago

TaleSlinger writes: Researchers from University of Bristol, UK found that boulders strewn 200m above sea level on Cape Verde, off the west coast of Africa, were ripped from cliffs below and washed up there by a tsunami between 170m and 270m (550-850ft). Researchers at Columbia University's Lamont-Doherty Earth Observatory dated the tsunami at 73,000 years ago. It's interesting that this is about the same time as the Mt. Toba Eruption and about the same time humans nearly became extinct.

Comments

Re:Mass extinction not caused by Mount Toba

[Anonymous Coward]

There have only been five "mass extinctions", the last one 66 million years ago:

https://en.wikipedia.org/wiki/...

There have been numerous megafloods and tsunamis, as well as enormous sea level rise over the past 14000 years. None of them are the cause of mass extinctions.

People love speculating "which one" is the cause of flood myths:

https://en.wikipedia.org/wiki/...

The fact of the matter is that megafloods and tsunamis are so frequent that there are many stories of great floods due to many actual great floods.

Ignore the "humans almost went extinct" bit

[93 Escort Wagon]

That's not from the Nature letter; apparently that's some off-the-wall addition from the submitter.

Since the submitter hasn't figured this out... This was a localized mega-tsunami. An enormous volcanic-induced landslide caused a huge wave to hit a nearby island. Just like other mega-tsunamis that are known to have occurred in Hawaii and Alaska. The scientists aren't talking about some global catastrophe - it would've sucked to be on that other nearby island, though.

Re:Ignore the "humans almost went extinct" bit

[Anonymous Coward]

The potential for extinction obviously wasn't due solely to a tsunami. What is being referred to is this:

Toba had erupted a number of times previously (one of these, about 840,000 years ago, was itself a super-eruption). What was significant about the event 74,000 years ago was the coincidence that an important period in human evolution was occurring at the same time. The Earth was already inhabited by a number of species closely related to us, such as Homo neanderthalensis (the Neanderthals) in Europe, and Homo erectus and Homo floresiensis (sometimes called the ‘hobbits’) in southeast Asia. All of these survived Toba, but some archaeologists have claimed that almost all the anatomically modern humans (our direct ancestors) were killed by the environmental effects the volcano caused, with the remaining people surviving in refuges in Africa. This scenario is based on data from genetics, and because it suggests that people were narrowed down from many to very few numbers, it is known as a genetic ‘bottleneck’.