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Ebb and flow of the sea drives world's big extinction events
University of Wisconsin-Madison ^ | Jun 15, 2008 | Unknown

Posted on 06/15/2008 12:06:45 PM PDT by decimon

MADISON - If you are curious about Earth's periodic mass extinction events such as the sudden demise of the dinosaurs 65 million years ago, you might consider crashing asteroids and sky-darkening super volcanoes as culprits.

But a new study, published online today (June 15, 2008) in the journal Nature, suggests that it is the ocean, and in particular the epic ebbs and flows of sea level and sediment over the course of geologic time, that is the primary cause of the world's periodic mass extinctions during the past 500[sc1] million years.

"The expansions and contractions of those environments have pretty profound effects on life on Earth," says Shanan Peters, a University of Wisconsin-Madison assistant professor of geology and geophysics and the author of the new Nature report.

In short, according to Peters, changes in ocean environments related to sea level exert a driving influence on rates of extinction, which animals and plants survive or vanish, and generally determine the composition of life in the oceans.

Since the advent of life on Earth 3.5 billion years ago, scientists think there may have been as many as 23 mass extinction events, many involving simple forms of life such as single-celled microorganisms. During the past 540 million years, there have been five well-documented mass extinctions, primarily of marine plants and animals, with as many as 75-95 percent of species lost.

For the most part, scientists have been unable to pin down the causes of such dramatic events. In the case of the demise of the dinosaurs, scientists have a smoking gun, an impact crater that suggests dinosaurs were wiped out as the result of a large asteroid crashing into the planet. But the causes of other mass extinction events have been murky, at best.

"Paleontologists have been chipping away at the causes of mass extinctions for almost 60 years," e[sc2]xplains Peters, whose work was supported by the National Science Foundation. "Impacts, for the most part, aren't associated with most extinctions. There have also been studies of volcanism, and some eruptions correspond to extinction, but many do not."

Arnold I. Miller, a paleobiologist and professor of geology at the University of Cincinnati, says the new study is striking because it establishes a clear relationship between the tempo of mass extinction events and changes in sea level and sediment: "Over the years, researchers have become fairly dismissive of the idea that marine mass extinctions like the great extinction of the Late Permian might be linked to sea-level declines, even though these declines are known to have occurred many times throughout the history of life. The clear relationship this study documents will motivate many to rethink their previous views."

Peters measured two principal types of marine shelf environments preserved in the rock record, one where sediments are derived from erosion of land and the other composed primarily of calcium carbonate, which is produced in-place by shelled organisms and by chemical processes. "The physical differences between (these two types) of marine environments have important biological consequences," Peters explains, noting differences in sediment stability, temperature, and the availability of nutrients and sunlight.

In the course of hundreds of millions of years, the world's oceans have expanded and contracted in response to the shifting of the Earth's tectonic plates and to changes in climate. There were periods of the planet's history when vast areas of the continents were flooded by shallow seas, such as the shark- and mosasaur-infested seaway that neatly split North America during the age of the dinosaurs.

As those epicontinental seas drained, animals such as mosasaurs and giant sharks went extinct, and conditions on the marine shelves where life exhibited its greatest diversity in the form of things like clams and snails changed as well.

The new Wisconsin study, Peters says, does not preclude other influences on extinction such as physical events like volcanic eruptions or killer asteroids, or biological influences such as disease and competition among species. But what it does do, he argues, is provide a common link to mass extinction events over a significant stretch of Earth history.

"The major mass extinctions tend to be treated in isolation (by scientists)," Peters says. "This work links them and smaller events in terms of a forcing mechanism, and it also tells us something about who survives and who doesn't across these boundaries. These results argue for a substantial fraction of change in extinction rates being controlled by just one environmental parameter."

- Terry Devitt, (608) 262-8282, trdevitt@wisc.edu

[sc1]The study starts in the Ordovician [sc2]100 years would refer to larger-scale changes in faunal composition


TOPICS: History; Science
KEYWORDS: catastrophism; climatechange; coastalenvironment; environment; godsgravesglyphs; gradualistnonsense; noitdoesnt; oceans; stillcrazyafterall; theseyears; wrongagain
First the tide rushes in.
Plants a kiss on the shore.
Then rolls out to sea.
And the sea is very still once more.
1 posted on 06/15/2008 12:06:45 PM PDT by decimon
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To: blam; SunkenCiv

Dire straits ping.


2 posted on 06/15/2008 12:08:24 PM PDT by decimon
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To: decimon

I knew it. We’re doomed. And my mortgage is just about paid off.

Just damn...


3 posted on 06/15/2008 12:09:05 PM PDT by abb (Organized Journalism: Marxist-style collectivism applied to information sharing)
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To: abb
I knew it. We’re doomed. And my mortgage is just about paid off.

Just damn...

Well, you can do it blam's way and go out with a bang or my way and be eaten by a giant shark.

"There were periods of the planet's history when vast areas of the continents were flooded by shallow seas, such as the shark- and mosasaur-infested seaway that neatly split North America during the age of the dinosaurs."

The sharks should be returning to Iowa about now.

4 posted on 06/15/2008 12:14:03 PM PDT by decimon
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To: decimon

Well, we’ve scheduled our vacation to Redneck Riviera for mid-October. We’re going, sharks, hurricanes or whatever. I gotsta have my yearly trip to Captain Anderson’s.

http://www.captanderson.com/


5 posted on 06/15/2008 12:20:09 PM PDT by abb (Organized Journalism: Marxist-style collectivism applied to information sharing)
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To: decimon
”For the most part, scientists have been unable to pin down the causes of such dramatic events.

I can’t help but to smell a rat here. This ‘study’ could become another variation of the ‘Global Warming Hoax’. Man, am I becoming cynical…

6 posted on 06/15/2008 12:22:22 PM PDT by ArchAngel1983 (Arch Angel- on guard)
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To: decimon
The sharks should be returning to Iowa about now.

No, Hillery is out of the running for now.
Say, I want some of these for my back yard pond.
"Mom, can we go feed Mr. Tet's Moasaurs? NO, NO, don't you remember what happened to little jimmy? Please mom we'll be careful..."


7 posted on 06/15/2008 12:29:49 PM PDT by tet68 ( " We would not die in that man's company, that fears his fellowship to die with us...." Henry V.)
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To: abb

If post #7 doesn’t scare you off then enjoy the meal. :-)


8 posted on 06/15/2008 12:40:32 PM PDT by decimon
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To: tet68

Life these days doesn’t seem so bad when you contemplate that age.


9 posted on 06/15/2008 12:42:34 PM PDT by decimon
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To: decimon

Considering that man is only occasionally not at the top of the food chain today, when he would definitely have been on the menue then.

And, no Huggies.


10 posted on 06/15/2008 12:48:39 PM PDT by tet68 ( " We would not die in that man's company, that fears his fellowship to die with us...." Henry V.)
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To: tet68
And, no Huggies.

And you'd need them if confronted by those creatures. :-)

11 posted on 06/15/2008 12:54:11 PM PDT by decimon
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To: decimon
Tilting of the earth's axis or retarding its rotation via a celestial close encounter is Nature's way of saying "Game Over".

I can't believe all those sedimentary strata and twisted geological features resulted from the earth's environment always being calm and serene, and that the geological layers gently built up over the millions of years and that the mountains of today resulted only from plate tectonics.

The theory of Catastrophism was in vogue until Darwin came out with his Theory. In order for it to work, the earth couldn't have been trashed by outside events. My bet is that creatures evolved because their environment suddenly changed - they had no choice - and a very high percentage never made it.

12 posted on 06/15/2008 1:41:17 PM PDT by Oatka (A society of sheep must in time beget a government of wolves." –Bertrand de Jouvenel)
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To: Oatka
The theory of Catastrophism was in vogue until Darwin came out with his Theory. In order for it to work, the earth couldn't have been trashed by outside events.

Well, I don't know but the timelines involved are so vast as to allow for more than one linear evoluntionary scale.

13 posted on 06/15/2008 1:51:50 PM PDT by decimon
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Deep-ocean vents are a source of oil and gas (evidence of abiogenic hydrocarbons)
Nature News | 31 January 2008 | Rachel Courtland
Posted on 01/31/2008 9:42:53 PM PST by neverdem
http://www.freerepublic.com/focus/f-news/1963050/posts


14 posted on 06/16/2008 8:33:26 AM PDT by SunkenCiv (https://secure.freerepublic.com/donate/_________________________Profile updated Friday, May 30, 2008)
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To: decimon
Thanks decimon.
a new study, published online today (June 15, 2008) in the journal Nature, suggests that it is the ocean, and in particular the epic ebbs and flows of sea level and sediment over the course of geologic time, that is the primary cause of the world's periodic mass extinctions during the past 500[sc1] million years.
s/b "a nothing-new study".
 
Catastrophism
 
· join · view topics · view or post blog · bookmark · post new topic ·
 

15 posted on 06/16/2008 8:33:55 AM PDT by SunkenCiv (https://secure.freerepublic.com/donate/_________________________Profile updated Friday, May 30, 2008)
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To: decimon; blam; StayAt HomeMother; Ernest_at_the_Beach; 1ofmanyfree; 21twelve; 24Karet; ...

· join list or digest · view topics · view or post blog · bookmark · post a topic ·

 
Gods
Graves
Glyphs
Thanks decimon.

To all -- please ping me to other topics which are appropriate for the GGG list.
GGG managers are Blam, StayAt HomeMother, and Ernest_at_the_Beach
 

· Google · Archaeologica · ArchaeoBlog · Archaeology magazine · Biblical Archaeology Society ·
· Mirabilis · Texas AM Anthropology News · Yahoo Anthro & Archaeo ·
· History or Science & Nature Podcasts · Excerpt, or Link only? · cgk's list of ping lists ·


16 posted on 06/16/2008 8:35:26 AM PDT by SunkenCiv (https://secure.freerepublic.com/donate/_________________________Profile updated Friday, May 30, 2008)
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To: abb
And my mortgage is just about paid off.

I'm upside down. Doom doesn't look all that bad...

17 posted on 06/16/2008 8:47:52 AM PDT by null and void (Bureaucracies are stupid. They grow larger by the square of their age and stupider by its cube.)
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To: decimon; blam

Ummmmmmmmm, what happened to blam?


18 posted on 06/16/2008 8:49:13 AM PDT by null and void (Bureaucracies are stupid. They grow larger by the square of their age and stupider by its cube.)
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To: decimon
Naaaaahhhh... not even close.

The moon was 70% closer then - causing daily tides from one to several hundred feet. They have completely misread whatever evidence they think they're presenting...

19 posted on 06/16/2008 8:51:12 AM PDT by xcamel (Being on the wrong track means the unintended consequences express train doesnt kill you going by)
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To: null and void
"Ummmmmmmmm, what happened to blam?"

LOL. I'm fine...just a little under the weather for a day or so.

20 posted on 06/16/2008 8:58:46 AM PDT by blam
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To: blam

Good. Right now, I’m the poster child for Mucinex myself...


21 posted on 06/16/2008 8:59:56 AM PDT by null and void (Bureaucracies are stupid. They grow larger by the square of their age and stupider by its cube.)
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To: blam
I'm fine...just a little under the weather for a day or so.

Yeah, you'll be alright. It's when you're under the climate that you need to worry.

22 posted on 06/16/2008 9:16:25 AM PDT by decimon
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To: Oatka; blam; SunkenCiv; null and void; xcamel; All

“My be is that creatures evolved because their environment suddenly changed”

I’m with you, although I think there is also room for more gradual transitions. Sudden and/or drastic: Yucatan meteor and Deccan trappes=dinosaur extinction; Permian, evidence of impact crater(s) possible, Siberian trappes for sure; significant die-offs as result of Chesapeake Meteor 50 mile diameter crater and larger in Siberia 34,000 years ago; I know there are other large boloid events, but have not yet compared their ages with extinction event. Then there is Firestone’s Cosmic Catastrophes proposal for the death of the megamammals about 13,000 years ago. Any major boloid or volcanic event could triger ice age type events, which would definitely cause a significant drop in sea levels which this article posits as cause rather than effect.

Slow and gradual: tectonic plate movement causing the closing off of open waterways could also affect ocean circulations which could cause more gradual changes in climate and fauna/flora, also the gradual pushing up of mountains (one source for twisted geological features) would change wind circulation and weather patterns. Subduction causes volcanos which if large enough or plentiful enough would changed environments. There are probably others, but it is time for my lunch, so goodby for now.

Blam: hope you are feeling better.


23 posted on 06/16/2008 9:25:30 AM PDT by gleeaikin
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To: xcamel; All

Do you have a link/source for your “the moon was 70% closer then?” And when was the then you refer to?


24 posted on 06/16/2008 9:27:18 AM PDT by gleeaikin
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To: gleeaikin; xcamel

here’s one:

When the Days Were Shorter
Alaska Science Forum (Article #742) | November 11, 1985 | Larry Gedney
Posted on 10/04/2004 10:31:59 AM PDT by SunkenCiv
http://www.freerepublic.com/focus/f-chat/1234919/posts

-and here’s some other topics probably related and/or of interest:

Moon over Chicxulub: Will Night Finally Fall on the Dinosaur-Extinction Debate?
American Scientist | November-December 1998 | Kirk Johnson
Posted on 09/21/2005 10:32:02 PM PDT by SunkenCiv
http://www.freerepublic.com/focus/f-chat/1489125/posts

Mass Extinctions: The New Catastrophism in the History of Life
LORE magazine, Milwaukee Public Museum | 1996 | Peter M. Sheehan, Curator of Geology
Posted on 10/10/2005 4:50:02 PM PDT by SunkenCiv
http://www.freerepublic.com/focus/f-chat/1500154/posts

Clare Places: Islands: Mutton Island or Enniskerry
(9th century catastrophe in Ireland)
Clare County Library | prior to November 19, 2005 | staff writer
Posted on 11/18/2005 11:58:58 AM PST by SunkenCiv
http://www.freerepublic.com/focus/f-chat/1524751/posts

In the shadow of the Moon
New Scientist | 30 January 1999 | editors
Posted on 08/31/2004 8:42:25 AM PDT by SunkenCiv
http://www.freerepublic.com/focus/f-chat/1203912/posts


25 posted on 06/16/2008 9:45:10 AM PDT by SunkenCiv (https://secure.freerepublic.com/donate/_________________________Profile updated Friday, May 30, 2008)
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To: gleeaikin
Look up lunar recession and it's effects on earth and geologic history, especially paleoevolution, and violent seas. You might learn something.
26 posted on 06/16/2008 9:54:00 AM PDT by xcamel (Being on the wrong track means the unintended consequences express train doesnt kill you going by)
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To: decimon

No doubt, though, it was all caused by man-made global whatever. Retroactively, of course.


27 posted on 06/16/2008 10:07:35 AM PDT by chesley ( Ya can't make chick'n dumplin's outta chick'n feathers!!)
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