The Earth sank twice, flooding the Eastern Amazon: Team finds shark tooth in northwest Amazon basin

The Earth sank twice, flooding the Eastern Amazon
Carcharhiniformes indet. tooth from the Saltarin core, Carbonera C2 Formation, early Miocene flooding. Credit: Jorge Carrillo

A tiny shark tooth, part of a mantis shrimp and other microscopic marine organisms reveal that as the Andes rose, the Eastern Amazon sank twice, each time for less than a million years. Water from the Caribbean flooded the region from Venezuela to northwestern Brazil. These new findings by Smithsonian scientists and colleagues, published this week in Science Advances, fuel an ongoing controversy regarding the geologic history of the region.

"Pollen records from oil wells in eastern Colombia and outcrops in northwestern brazil clearly shows two short-lived events in which ocean water from the Caribbean flooded what is now the northwest part of the Amazon basin," said Carlos Jaramillo, staff scientist at the Smithsonian Tropical Research Institute and lead author of the study.

"Geologists disagree about the origins of the sediments in this area, but we provide clear evidence that they are of marine origin, and that the flooding events were fairly brief," Jaramillo said. His team dated the two flooding events to between 17 to18 million years ago and between 16 to 12 million years ago.

Several controversial interpretations of the history of the region include the existence of a large, shallow sea covering the Amazon for millions of years, a freshwater megalake, shifting lowland rivers occasionally flooded by seawater, frequent seawater incusions, and a long-lived "para-marine metalake," which has no modern analog.

Jaramillo assembled a diverse team from the Smithsonian and the University of Illinois at Urbana-Champaign; Corporacion Geologica Ares; the University of Birmingham; the University of Ghent; the Universidad del Norte, Baranquilla, Colombia; the University of Alberta, Edmonton; the University of Zurich; Ecopetrol, S.A.; Hocol, S.A.; the Royal Netherlands Institute for Sea Research at Utrecht University; the University of Texas of the Permian Basin; and the Naturalis Biodiversity Center.

Extension of Continental, Marginal and Marine environments from ~18.4 to ~10.5 Ma showing the the two marine incursions reported in this study. Credit: Carlos Jaramillo, German Bayona and Edward Duarte, using Gplates and VideoPad by NCHsoftware

Together, they examined evidence including more than 50,000 individual pollen grains representing more than 900 pollen types from oil drilling cores from the Saltarin region of Colombia and found two distinct layers of marine pollen separated by layers of non-marine types. They also found several fossils of marine organisms in the lower layer: a shark tooth and a .

"It's important to understand changes across the vast Amazonian landscape that had a profound effect, both on the evolution and distribution of life there and on the modern and ancient climates of the continent," Jaramillo said.

The Earth sank twice, flooding the Eastern Amazon
Modern Carcharhinus shark is similar to the fossil shark found in the early Miocene flooding. Credit: Gaby Carías Tucker and Alberto Blanco Dávila

Explore further

Andes Mountains Are Older Than Previously Believed

More information: "Miocene flooding events of western Amazonia," Science Advances (2017). advances.sciencemag.org/content/3/5/e1601693
Journal information: Science Advances

Citation: The Earth sank twice, flooding the Eastern Amazon: Team finds shark tooth in northwest Amazon basin (2017, May 3) retrieved 23 April 2019 from https://phys.org/news/2017-05-earth-sank-eastern-amazon-team.html
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May 03, 2017
Must have been all those cars around millions of years ago that raised the temps and melted the poles, causing the Amazon flooding. What's that you say? That's silly? Do you mean to say warming can occur naturally, independent of...man's influence?! Who'd a thunk it?

May 04, 2017
We see possible evidence for much more recent catastrophe in these regions as well in the form of dark earth.

http://terrapreta...restsorg

"Above ground, rainforests like the Amazon basin flourish as biological hot spots with exuberant growth and a riot of plant and animal species.

But the red and yellow soils below are notoriously poor in nutrients and organic matter. Once the lush vegetation is cleared, the heavy rains and tropical sun quickly decompose even that small reservoir.

Except not in thousands of patches dotted along the Amazon River and its tributaries, where dark, friable soil extends metres deep, fertile in nutrients and organic material. In total, an area the size of France may be covered by this Indian black earth, called terra preta do Indio in Portuguese.

'The textbooks say it shouldn't be there ..."

(cont'd)

May 04, 2017
(cont'd)

"... Lehmann is one of a small band of researchers in the U.S., Europe and Brazil who are deciphering the mysteries of terra preta after the phenomenon was 'discovered' for the third time a decade ago. At a major scientific meeting here last week, they explained that the black earth of the Amazon is exciting for widely disparate scientific reasons:

1) Archaeology and anthropology. Terra preta typically is stuffed full of shards of sophisticated pottery discarded as much as 2,000 years ago by an advanced civilization whose existence wasn't even suspected ...

In slash-and-burn, dry brush and grass are burned in open fires, spewing vast quantities of carbon dioxide into the atmosphere and leaving only small amounts of nutrients in the ash that's then dug into the ground.

By contrast, slash-and-char involves burning wet vegetation, so it smoulders underneath a layer of dirt and straw ..."

(cont'd)

May 04, 2017
(cont'd)

"... Robbed of oxygen, the fire only partly burns any wood or stalks, leaving most as tiny chunks of charcoal. This bio-char is turned into the soil ...

Why people living on hills overlooking many rivers in Brazil two millennia ago devised this approach is still a subject of debate, as is how they added all the extra organic content and ensured the soil was teeming with beneficial bugs and other micro-organisms ..."

What the article fails to mention is that dark earth is also a feature of the Roman ruins. Tens of meters of it had to be excavated to reveal some of those ruins in spots near the Coliseum. We'd be wise to consider that people did not create this. The combination of fire, flood and biomass rich in nutrients suggests a devastating, large-scale natural catastrophe.

May 04, 2017
Regarding Terra Preta, and its vicinity to ruins. Its interesting to note that as the rainforest is clear cut ... large prehistoric complexes of past cities, villages, roads, canals are being exposed. Showing that the history of the amazon doesn't match our history books.

I have heard a popular youtube armchair archaeologist hypothesize that perhaps the amazon jungle is a result of human intervention with the soil, causing the rapid spread of vegetation. Sounds plausible.


May 04, 2017
Must have been all those cars around millions of years ago that raised the temps and melted the poles, causing the Amazon flooding. What's that you say? That's silly? Do you mean to say warming can occur naturally, independent of...man's influence?! Who'd a thunk it?


That's like saying that, since lightning strikes can cause fires naturally, human activity never does, and furthermore, that fire departments aren't needed.

May 04, 2017
Its astounding what interpretations can be drawn from this: A clear view of the history of the Med prior to the Grecian Dark Ages could mean that the world had a large population engaged in producing not only pottery BUT the early copper tools as well. Not stated as sharply as it should be is the clear cutting of the Med and upland woods for industrial use. Why should we limit this understanding to just the Med region? Could not the equatorial lands all have been connected socially by ships traversing the Atlantic prior to a global catastrophe known as the Greek Dark Ages ONLY because we have yet to identify this collapse in the rest of the equatorial world.

May 04, 2017
Re: "I have heard a popular youtube armchair archaeologist hypothesize that perhaps the amazon jungle is a result of human intervention with the soil, causing the rapid spread of vegetation. Sounds plausible."

Sounds uniformitarian.

May 04, 2017
Regarding Terra Preta, and its vicinity to ruins. Its interesting to note that as the rainforest is clear cut ... large prehistoric complexes of past cities, villages, roads, canals are being exposed. Showing that the history of the amazon doesn't match our history books.

I have heard a popular youtube armchair archaeologist hypothesize that perhaps the amazon jungle is a result of human intervention with the soil, causing the rapid spread of vegetation. Sounds plausible.

And it's also "possible" that those civilizations migrated there BECAUSE of the soil...

May 06, 2017
Maybe the words "sank twice" are not as far from the truth as might be believed:

In the beginning, the earth was covered in water and only afterwards the land appeared.

Then again because of sin, the earth was flooded to kill off all animals, birds and human beings that were not conveyed and kept safe in the ark.

The waters dissipated, carrying loads of sediment that covered the whole surface of the earth and some land mass was uplifted into the mountains we see today. Hence we find all kinds of things like marine animals buried in the sediments on top of even the highest peaks.

Therefore the quoted statement is in fact quite close to the truth. However as stated, it just continues to mislead the people by insisting on the naturalistic explanation for everything.

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