Ice Age Floods cause mass extinctions?

[nannoh]

During the last Ice Age (18,000 to 12,000 years ago), and in multiple previous Ice Ages, cataclysmic floods inundated portions of the Pacific Northwest from Glacial Lake Missoula, pluvial Lake Bonneville, and perhaps from subglacial outbursts. Glacial Lake Missoula was a body of water as large as some of the USA's Great Lakes. This lake formed from glacial meltwater that was dammed by a lobe of the Canadian ice sheet. Episodically, perhaps every 40 to 140 years, the waters of this huge lake forced its way past the ice dam, inundating parts of the Pacific Northwest. Eventually, the ice receded northward far enough that the dam did not reform, and the flooding episodes ceased.

http://www.iceagefloodsinstitute.org/

It was in 1923 that J Harlen Bretz published the first in a series of scientific papers in which he proposed that the severely eroded Channeled Scabland, Dry Falls, and other immense geologic features had been formed by a huge, powerful flood that had swept through the Columbia Basin during the Ice Age.

Despite his peers’ doubt and opposition, he resolutely maintained that direct examination of the geologic evidence could lead only to that conclusion. But Bretz was unable to identify the source or cause of such catastrophic flooding.

Earlier, in 1910, another geologist, Joseph T. Pardee, had described evidence of a great ice dammed lake, Glacial Lake Missoula, that had formed during the Ice Age in northwestern Montana. However, Bretz didn't see the connection between the glacial lake in Montana and the features he described in Eastern Washington. Then, in 1940, Pardee reported on his discovery of giant ripple marks, 50 feet high and 200-500 feet apart, that had formed on the floor of Glacial Lake Missoula. These huge, current-related features, along with other newly-found landforms, dramatically confirmed that the lake had suddenly emptied to the west, unleashing the tremendously powerful erosive forces that shaped many of the landforms found in the Columbia Basin.

More research followed, and new perspectives became available from aerial photography. Among geologists, the concept of a catastrophic flood came to be accepted by the late 1950s.

http://www.iceagefloodsinstitute.org/aboutfloods/puzzlesolved.html

Drumlins and subglacial meltwater floods.

Since 1983, several investigators have developed a theory of drumlin formation by catastrophic flooding due to the release of meltwater that is believed to have accumulated beneath melting ice sheets. The proposed catastrophic sheet floods, as wide as the drumlin fields, formed the drumlins and related streamlined landforms, such as flutings, over wide areas. So-called rogen moraine, consisting of transverse ridges of drift, often found associated with drumlins, is reinterpreted in the meltwater flood hypothesis as possible giant current ripples.

http://www.sentex.net/~tcc/sgfcrit.html

Question and answer with geologist Dr. John Shaw

http://www.sentex.net/~tcc/sgfrep.html


These articles and many others disclose a little known catastophic chapter in the Earth's history that appears to raise a range of questions about the cause of many geological features in certain areas to the sudden and wide spead mass extinctions that took place around the same time as these aleged floods.

You can give your opinion, pro or con, with supporting reference material, in the space below. Thank you.

 

[Bystander]

Homework? You've got papers on the scablands, history of mainstream geological thoughts, and the "recent" synthesis of the available evidence for large, repetitive, localized flood events; how are you getting from local flooding to mass extinction?

 

[nannoh]

Homework? You've got papers on the scablands, history of mainstream geological thoughts, and the "recent" synthesis of the available evidence for large, repetitive, localized flood events; how are you getting from local flooding to mass extinction?

You're right to point that out. I am referring to the Mammoths and other northern mega-fauna:

Web definitions for Mass extinction:

The name given to a period of especially high rates of extinction of species. Several such events are seen in the fossil record.

palaeo.gly.bris.ac.uk/communication/boulton/glossary.html

- Definition in context

How do we define a Mass Extinction? Traditionally, within geological sciences, mass extinctions have been seen as some type of catastrophe for the world's biota. There have been many, long-term discussions about the importance of such catastrophes during Earth history, and especially about their importance for long-term evolution. In Darwin's time (1850-1860s) the view that catastrophes were an integral part of evolution was frowned upon, and seen as a fall-back to ancient theories of catastrophism, as exemplified by the description of Noah's flood in the Bible. This view has changed recently, and modern ideas of catastrophism are part of an active discussion of 'internal' and 'external' causes of evolution. Internal causes meaning causes internal to the biota (such as competition, evolution of diseases), external meaning causes external to the biota (such as volcanic eruptions or nuclear war).

http://ethomas.web.wesleyan.edu/ees123/mass_extinctions.htm

Homework?

 

[Bystander]

Yes, if it looks like homework, the forum policy is that the question go into the "Homework Help" area, and that the poster demonstrate effort toward answering the question.

Again, how do you propose to connect local flooding events to extinction events?

 

[nannoh]

Yes, if it looks like homework, the forum policy is that the question go into the "Homework Help" area, and that the poster demonstrate effort toward answering the question.

Again, how do you propose to connect local flooding events to extinction events?

Evidence shows that the on slaught of Ice Age floods was not so localized:

Hills point to catastrophic Ice Age floods

Fields of low hills that cover parts of inland Canada and the northern United States may seem quite distant from the watery world of Atlantis. Yet a Canadian geologist proposes these hills formed from huge Ice Age floods that sharply raised global sea levels and could have spawned myths of a swamped continent.

"There's nothing in recorded history that matches the size of these floods," says John Shaw of Queen's University in Kingston, Ontario, who has estimated the extent of the floods from the size of the ridges.

Called drumlins--a word derived from Old Irish -- these hills appear in concentrated fields in North America, Scandinavia, Britain and other areas once covered by ice. When seen from above, the aligned knolls sometimes look like a basket of eggs lying on their sides and pointing in the same direction. Some drumlins are made of sediments deposited onto bedrock; others are ridges carved out of the rock.

Most geologists believe drumlins developed gradually from the grinding action of heavy ice sheets as they moved over the land. But in the last several years, Shaw and others have proposed the controversial idea that floods of water flowing beneath the ice created many of the North American drumlins and possibly others around the world. They base this hypothesis on the shapes drumlins share with other land forms sculpted by meltwater.

http://www.findarticles.com/p/articles/mi_m1200/is_n14_v136/ai_8002743

Also see this article:

Himalayan Ice Dams Created Huge Lakes, Floods

Environment News Service, December, 2004

SEATTLE, Washington (ENS) — --> Ice dams across the deepest gorge on Earth created some of the highest elevation lakes in history, according to new research from University of Washington geologist David Montgomery, a professor of Earth and space sciences.

The most recent of these lakes, in the Himalaya Mountains of Tibet, broke through its ice barrier somewhere between 600 and 900 AD, causing massive torrents of water to pour through the Himalayas into India, Montgomery said.

Geological evidence points to the existence of at least three lakes, and probably four, at various times in history when glacial ice from the Himalayas blocked the flow of the Tsangpo River in Tibet, he said .

http://www.findarticles.com/p/articles/mi_kmens/is_200412/ai_n8609042

And further evidence of a European ice age meltdown:

The Baltic Sea, with its unique brackish water, is a result of meltwater from the Weichsel glaciation combining with saltwater from the North Sea when the straits between Sweden and Denmark opened. Initially, when the ice began melting about 10,300 ybp, seawater filled the isostatically depressed area, a temporary marine incursion that geologists dub the Yoldia Sea. Then as post-glacial isostatic rebound lifted the region about 9500 ybp, the deepest basin of the Baltic became a freshwater lake, in palaeological contexts referred to as Ancylus lake, which is identifiable in the freshwater fauna found in sediment cores. The lake was filled by glacial runoff, but as worldwide sea level continued rising, saltwater again breached the sill about 8000 ybp, forming a marine Littorina Sea which was followed by another freshwater phase before the present brackish marine system was established. "At its present state of development, the marine life of the Baltic Sea is less than about 4000 years old," Drs Thulin and Andrushaitis remarked when reviewing these sequences in 2003.
Overlaying ice had exerted pressure on the Earth's surface. As a result of melting ice, the land has continued to rise yearly in Scandinavia, mostly in northern Sweden and Finland where the land is rising at a rate of as much as 8-9 mm per year, or 1 meters in 100 years. This is important for archeologists since a village that was coastal in the Nordic Stone Age now is inland.

http://en.wikipedia.org/wiki/Wisconsin_glaciation

This article has other examples of other areas as well.

This type of study is relatively new and so not many sites have been thoroughly surveyed. My question is more about if anyone has further evidence of these floods around the world and if this type of catastrophic event could have contributed to the demise of mega fauna in north america, siberia and mongolia or related areas.

Just asking for a little help here. Plus, its a fascinating study, don't you agree?!

 

[Andre]

There might be an interconnection between all those "floods" and extinctions but it's probably a lot more complicated.

The late Pleistocene megafauna extinction started around 14000 calendar years ago with horses in Alaska and woolly rhinos in Eurasia and it ended probably 4150 Calendar years ago with the last population of woolly mammoths on Wrangel island.

The Alaskan horses decreased notably in size during their last few milleniums of existence and this is also true for most woolly mammoth populations. Furthermore, together with extinction of the horses was a strong population explosion from modern megafauna like elk and bison. There is also distinct evidence of biotope change from dry steppe to wood-lands. No signs of floods there as far I know.

The bulk of the extinction appeared to have been around the end of the Younger Dryas between 11,500 and 10,500 years but the giant (irish) Elk survived until some 6000 years ago. There may be a case for the Americal mastodons as well having survived to a few milleniums ago.

Not only Eurasia and North America but the extinction took also place in South America, mostly giant sloths, mastodon and Gomphotherium (four tusked elephants).

Now it could be that many factors contributed to the extinctions, however if such contribution is dispensable, it's not the common cause. Humans may have killed some, even a lot of megafauna but certainly not all. Floods may have flushed away many specimens. Diseases may have decimated weakened hurds. But the common denominator for all extinctions appears to be change in habitat and consequently the loss of the battle for survival.

The changes in habitat appear to have one comemon cause: climate changes. Those were there all the time.

See also:

https://www.physicsforums.com/showthread.php?t=127240

https://www.physicsforums.com/showthread.php?t=126676

 

[Bystander]

Evidence shows that the on slaught of Ice Age floods was not so localized:

Each event is local. Did flood events take place over a large area of the world? Sure, but not simultaneously.

(snip)

This type of study is relatively new and so not many sites have been thoroughly surveyed. My question is more about if anyone has further evidence of these floods around the world and if this type of catastrophic event could have contributed to the demise of mega fauna in north america, siberia and mongolia or related areas.

Just asking for a little help here. Plus, its a fascinating study, don't you agree?!

The debate between "catastrophism" and "uniformitarianism" has moved to the middle ground of "both." There are little catastrophes (local) and global catastrophes --- you need something on a global scale to rationalize mass extinction events, and sporadic collapses of ice dams on meltwater lakes don't really fit into that category. Yes, local populations of this, that, or the other can be wiped out, and surviving populations from elsewhere expand into the cleared area to be wiped out during the next event. Wipe out every population everywhere at one time? No.

 

[nannoh]

There might be an interconnection between all those "floods" and extinctions but it's probably a lot more complicated.

The late Pleistocene megafauna extinction started around 14000 calendar years ago with horses in Alaska and woolly rhinos in Eurasia and it ended probably 4150 Calendar years ago with the last population of woolly mammoths on Wrangel island.

The Alaskan horses decreased notably in size during their last few milleniums of existence and this is also true for most woolly mammoth populations. Furthermore, together with extinction of the horses was a strong population explosion from modern megafauna like elk and bison. There is also distinct evidence of biotope change from dry steppe to wood-lands. No signs of floods there as far I know.

The bulk of the extinction appeared to have been around the end of the Younger Dryas between 11,500 and 10,500 years but the giant (irish) Elk survived until some 6000 years ago. There may be a case for the Americal mastodons as well having survived to a few milleniums ago.

Not only Eurasia and North America but the extinction took also place in South America, mostly giant sloths, mastodon and Gomphotherium (four tusked elephants).

Now it could be that many factors contributed to the extinctions, however if such contribution is dispensable, it's not the common cause. Humans may have killed some, even a lot of megafauna but certainly not all. Floods may have flushed away many specimens. Diseases may have decimated weakened hurds. But the common denominator for all extinctions appears to be change in habitat and consequently the loss of the battle for survival.

The changes in habitat appear to have one comemon cause: climate changes. Those were there all the time.

See also:

https://www.physicsforums.com/showthread.php?t=127240

https://www.physicsforums.com/showthread.php?t=126676

This is great! Thank you Andre for bringing some perspective about root causes of meltdowns and that sort of thing. If would follow that an in depth study of the cause of prehistoric climate change would be underway, as it seems to be according to your threads. The Earth's climate cycle appears to have a long wave frequency to it that is about as predictable as the weather!

 

[nannoh]

Each event is local. Did flood events take place over a large area of the world? Sure, but not simultaneously.

(snip)


The debate between "catastrophism" and "uniformitarianism" has moved to the middle ground of "both." There are little catastrophes (local) and global catastrophes --- you need something on a global scale to rationalize mass extinction events, and sporadic collapses of ice dams on meltwater lakes don't really fit into that category. Yes, local populations of this, that, or the other can be wiped out, and surviving populations from elsewhere expand into the cleared area to be wiped out during the next event. Wipe out every population everywhere at one time? No.

You're right bystander. There appears to be floods that built up and took place in different areas of the planet at different times. This seems to answer my question about extinctions and floods. Not too much to go on that says a whole species was wiped out because of a flood. Perhaps sub-species were displaced as you say but not whole species. These sub-glacial build ups and the supra-glacial lakes didn't seem to cause any where near as much of an extinction as the large body impact of 65 million years ago that left a crater in the gulf of mexico.

It was a mistake for me to include the extinction possiblity with this thread. I wish I could edit my title. The Ice Age Flood analytical studies are facsinating enough without the idea of a bunch of drowning mammoths. Thank you for at least reading some of what I've written here.

 

[Pythagorean]

we had horses in Alaska?

 

[Andre]

You bet

http://www.nature.com/nature/journal/v426/n6963/abs/nature02098.html

 

[nannoh]

What gets me is everytime I search ice age floods on google I get these creationist sites trying to allocate some sort of significance of the biblical floods to these catastrophic releases of meltwater from glaciers.

The only connection I see between the biblical floods and ice age floods is that, at one time, a record was made of these flood events and it ended up in the biblical record. This would be a record surviving from around 9000 years ago around when the last glacial maximum began to subside.

 

[Andre]

Well considering all kinds of natural floodings world wide, it's not that strange that there is an incredible amount of flood tales.

But this is for amusement only, there is no evidence or connection anywhere. It may be noted though that the multiple spikes in the Greenland Ice cores between 14,500 and 12800 Calendar years BP, known as the Bolling Allerod event and the onset of the Holoceen as of 11,650 Calendar years ago, do show a remarkakle climate change that is alleged to be mostly temperature but in the geologic proxies it mostly shows as precipitation changes. And quite severly. But not Noah's flood.

It appear that this also caused the spikes in the extinction events.

 

[mhalavo]

It was a mistake for me to include the extinction possiblity with this thread. I wish I could edit my title. The Ice Age Flood analytical studies are facsinating enough without the idea of a bunch of drowning mammoths. Thank you for at least reading some of what I've written here.

I don't think it was a mistake. Some believe that he massive amounts of freshwater released into the oceans from these floods shut down the thermohaline current:

http://www.newscientist.com/article.ns?id=dn8558

This event possibly triggered wide reaching climate change that "could" of caused extinctions.

 

[Mk]

I was very surprised when I heard Al Gore say that in his masterpiece movie. He said a large flood completely shut down thermohaline circulation! Egads!

 

[Andre]

No, there are still looking for the source of all that alleged melt water, it could not be the Mississippi area, because that stopped flowing. It could not be the Saint Lawrence River, dates of the evidence is wrong there. It could not be the Hudson bay, - no evidence. etc,

My guess is that it was when the clathrate gun of the Amazon fan stopped 12,800 years ago which also stopped the increased surface flow to the north.

 

[nannoh]

There is recorded evidence in India, as recent as the 1800s, where a build up of meltwater was suddenly released by a glacial dam in the Himalayas and annihilated 7000 men in the Sikh Army who were camped in the vicinity.

There are quite a few facts from that area about Ice Age Floods that I will be able to offer at a later date, including a reference for the record of the Sikh Army losses to meltwater flooding in the 1800s.

These Ice Age and Glacial meltwater release events held an emense power that has not been as thoroughly studied as other geological and oceanic events. It is said that the meltwater of the Ice Age, over an 8000 year period, contributed to a rise in sea level of many meters (I will provide references). Large amounts of fresh water added to various parts of the ocean could also have had a damaging effect to saltwater adapted life forms. Whether the cold water from glaciers would effect currents and so forth, as some have suggested, requires better studies.

As Andre has pointed out, the amount of climate change taking place around the same time as the Ice Age Floods may prove to be the more fascinating study that would help to disclose why the climate was changing in the first place. This sort of knowledge could also apply to an understanding of why today's rather erratic weather and climate statistics are taking place.

 

[nannoh]

Reference for the above posting:

Its from an article in Geology Today, pp 197, Nov.- Dec. 1998, titled "Flashfloods, earthquakes and uplift in the Pakistan Himalayas" by Butler, Owen and Prior.

There is a small consensus among geologists that holds to the idea that there was a global superflood around 11,600 years ago. These people are not born again baptists or maintaining any religious significance about the flood (actually, three global superfloods). It is thought that the flood covered land masses as far apart as the eastern Mediterranean and the Atlantic Ocean.

One of the pioneers of Isotopic analysis of deep-sea sediments as a way to study the Earth's past climates, Cesare Emiliani, Professor in the Department of Geological Sciences at the University of Miami, produced interesting evidence of cataclysmic global flooding "between 12,000 and 11,000 years ago".

Robert Schoch, Professor in the Department of Geology at Boston University, observes that there was also a dramatic warming of the Earth's climate in the same period - the Preboreal - and that overall there is a

stunning line up in time between the sudden warming of 9645 bc, Emiliani's scenario of a massive freashwater flood pouring into the Gulf of Mexico, and (the written accounts found in Plato's "Timaeus and Critias of floods swallowing up a civilization).

A majority of Geologists saw the rise in sea level during the Preboreal as slow and nothing more than a meter per year or so. But since Emiliani's findings first began to undermine that view in the 1970s there are more and more studies that show how very cataclysmic the meltdown of the Ice Age could in fact have been.

I will try to go back to a more indepth study of India and the evidence there of massive flooding that stemmed from melting of the Himalayan glaciation during the LGM. It is particularly pertinent to this topic since its effects have been well recorded in various formats by many generations of Indian people, from the spoken word of the Rig Veda to written Sanskrit. And there has been a lot of research done in the area as well, showing dramatic changes that took place on the coasts of India and in the interior around 10,000 years ago, due to flooding.

 

[Andre]

Perhaps have a look at this thread, Nannoh

https://www.physicsforums.com/showthread.php?t=125669

 

[Pythagorean]

You bet

http://www.nature.com/nature/journal/v426/n6963/abs/nature02098.html

that's cool!

I want PICTURES! How did they compare to normal horses? Where they bigger and harrier?

 

[Andre]

http://www.beringia.com/02/02maina14.html may help, it was definitey much smaller.

Paleontology can be cool indeed, check the mastodom thread.

 

[nannoh]

Perhaps have a look at this thread, Nannoh

https://www.physicsforums.com/showthread.php?t=125669

Can isotope levels taken from ocean bottom sediments also show increased fresh water inundation besides the aledged temp. changes that isotopes are proported to measure?

 

[Mk]

that's cool!

I want PICTURES! How did they compare to normal horses? Where they bigger and harrier?

I don't think anyone was around to take any pictures.

 

[nannoh]

Jökulhlaups (jökull = glacier, hlaup = floodburst)

Floods brought on by glaciation are not uncommon. Imagine the force and magnatude of the floods from the LGM.

In this article the effects of "Jökulhlaups" on land forms is discussed as well as the effects of large amounts of fresh water on sea life. The impact of a flash flood from a glacier traveling at 60 to 80 miles an hour is also something to calculate when considering the survival or lack of it in land-based flora and fauna.

Jökulhlaups (jökull = glacier, hlaup = floodburst) happen inevitably when a glacier becomes a dam. At Vatnajökull, the ice cap dammed meltwater inside itself. Elsewhere a glacier might surge into a narrow river valley, like a landslide across a highway, and the resulting dam collects itself a lake. But ice has no strength, and the lake quickly destroys the dam when it can overtop it. Another thing about a dam made of ice is that ice is lighter and colder than water. Water both melts and floats an ice dam, and once the water first trickles underneath it the dam, no matter how large, swiftly fails. Hence the weird word for this special event.

They happen elsewhere than Iceland. In May 1986, Alaska's Hubbard Glacier had a vigorous surge that took its snout well past its usual endpoint. At a clip of dozens of meters per day, Hubbard moved into the shallows of Disenchantment Bay and formed a dam across Russell Fiord at its entrance. In that instant Russell Fiord became Russell Lake, which began to rise. The rising lake threatened to overflow elsewhere, into an ancient spillway that had been active in similar previous situations. The brackish water would flood the Situk River and ruin its world-class fishing—and the economy of Yakutat, the nearest town.

But on 7 October, a jökulhlaup saved the day. At one point it carried several cubic kilometers of water per minute into the Gulf of Alaska, along with much of Hubbard's snout. The U.S. Geological Survey said "the peak flow rate may have been the greatest water discharge to occur in North America and the largest glacier outburst in the world during the past few centuries" (it happened again in 2002). Yakutatans, at home in this dramatic setting for untold centuries, took it in stride too.

But we know of some jökulhlaups that make those of 1986 and 1996 pipsqueaks. Late in the last glacial period, about 13,000 years ago, part of the Cordilleran icesheet stoppered up...

http://geology.about.com/od/flooding/a/aa_041397jokul.htm

 

[Pythagorean]

I don't think anyone was around to take any pictures.

sketches, based on skeletons, derived by people who have a good idea of muscle and tissue structure based on skeletal structure is good enough, and also is what Andre provided above. They look like mutant horse-ponies!

 

[nannoh]

Can isotope levels taken from ocean bottom sediments also show increased fresh water inundation besides the aledged temp. changes that isotopes are proported to measure?

I'm not sure if this answers my question.

Stable isotopes
Deuterium (d 2H) and Oxygen-18 (d 18O)

Deuterium and oxygen-18 compositions of water samples provide a useful tool for investigating hydrological processes in surface and groundwater systems. In groundwater, the 2H and 18O signature gives an indication of the climatic conditions under which recharge took place. In surface water/catchment studies, stable isotopes have been used to estimate retention times and the hydrologic response of catchments to rainfall.

The Service also supports research work in which stable isotopes are used to identify the different sources of water taken up by plants. In addition it is involved in the use of single (deuterated) and double (18O and deuterated) labelled water in estimation of energy metabolism and fat-free mass in humans, mammals and reptiles.

http://www.clw.csiro.au/services/isotope/index.html#stable

I am asking about this because I want to find out if its possible to use the composition of sediments to determine periods of low salinity that could only be caused by an inundation of freshwater into a coastal, marine environment.

 

[Mk]

I want to know now too.

 

[nannoh]

I want to know now too.

You could find out if your lizard is gaining weight with isotopic analysis.

 

[Andre]

Okay then, fasten seatbelts, here we go.

The oxygen isotope ratio (d18O) from ocean sediment cores are measured from the calcium carbonate of the shells from certain foraminifera species, planktonic or benthic (bottom). The oxygen comes from variations of the reactions

(1) CO2 + H2O -> CO3(2-) + 2H+,
(2) CO3(2-) + Ca (2+) -> CaCO3.

Both as ions in the sea water. Some CO2 comes from the atmosphere, some comes from biotic marine cycles. I think that the latter is assumed to prevail, since the amount of CO2 in the oceans is some 60-70 times more than the amount in the atmosphere.

Now the ratio if 18O atoms depends on the ratio of the source and the fractination processes as well as conditions like temperature salinity, acidity. Moreover each species has it's own fractination constant.

The prevailing paradigm is that in the deepsea, conditions are pretty constant including the temperatures. Hence the concentration of 18O in the water, before it's fixed in calcium carbonate shells is thought to be the main cause of variation.

And the main cause of variation in d18O of the seawater is thought to be governed by the amount of water that is retained in the water cycle, the evaporation favors light 16O isotopes. Hence, the more ice sheets depleted with 18O, the less water in the ocean, the stronger the 18O signal.

There is a big problem with that idea though. The inertia of the oceans. If fresh meltwater enters the oceans, it would take centuries to millenia before the water was well mixed and the signal turning up in the benthic foraminifera proxies.

But there is no inertia delay, when comparing ice cores with benthic cores, moreover the amount of ice needed to balance the numbers is far greater than was really present during the last glacial maximum, which suggest that this "basin effect" is only minor. So what's really showing in the ocean cores appears to be mainly something else, sudden changes in parameters other than source ratio of d18O

But the math here is having one expression with three unknowns so we really need two more mathematical expressions with those unknows to figure out those parameters. Anything else is guesswork.

 

[nannoh]

Okay then, fasten seatbelts, here we go.

The oxygen isotope ratio (d18O) from ocean sediment cores are measured from the calcium carbonate of the shells from certain foraminifera species, planktonic or benthic (bottom). The oxygen comes from variations of the reactions

(1) CO2 + H2O -> CO3(2-) + 2H+,
(2) CO3(2-) + Ca (2+) -> CaCO3.

Both as ions in the sea water. Some CO2 comes from the atmosphere, some comes from biotic marine cycles. I think that the latter is assumed to prevail, since the amount of CO2 in the oceans is some 60-70 times more than the amount in the atmosphere.

Now the ratio if 18O atoms depends on the ratio of the source and the fractination processes as well as conditions like temperature salinity, acidity. Moreover each species has it's own fractination constant.

The prevailing paradigm is that in the deepsea, conditions are pretty constant including the temperatures. Hence the concentration of 18O in the water, before it's fixed in calcium carbonate shells is thought to be the main cause of variation.

And the main cause of variation in d18O of the seawater is thought to be governed by the amount of water that is retained in the water cycle, the evaporation favors light 16O isotopes. Hence, the more ice sheets depleted with 18O, the less water in the ocean, the stronger the 18O signal.

There is a big problem with that idea though. The inertia of the oceans. If fresh meltwater enters the oceans, it would take centuries to millenia before the water was well mixed and the signal turning up in the benthic foraminifera proxies.

But there is no inertia delay, when comparing ice cores with benthic cores, moreover the amount of ice needed to balance the numbers is far greater than was really present during the last glacial maximum, which suggest that this "basin effect" is only minor. So what's really showing in the ocean cores appears to be mainly something else, sudden changes in parameters other than source ratio of d18O

But the math here is having one expression with three unknowns so we really need two more mathematical expressions with those unknows to figure out those parameters. Anything else is guesswork.

This all makes perfect sense Andre.

Do we need the exoskeletons, calcium carbonate shells and other remains to read the the saline or fresh water content levels at given intervals over time in a basin or coastal area?

Is there a way to use the sedimentary layers in those areas that will show whether or not there has been an influx of freshwater from further inland or from some other source?

For instance, runoff always carries with it the pollen and other tell tale evidence from the area it is coming from. A sedimentary layer with a high content of inland pollens or soils would be evidence that it was laid down during a period disturbance from high run off. This would have to be compared with existing delta areas. Most rivers are remnants of massive meltwater from glacial runoff and I would think that the submarine sedimentary layering at the mouths of those rivers would provide an example of what the sedimentation of freshwater incursion would look like without relying on the fingerprint of the biological and chemical cycles of foraminifera species, planktonic or benthic.