|
Shift in thought that an asteroid may NOT have killed dinosaurs
|
View this Thread in Original format
| occrider |
For all those interested.
http://www.rednova.com/news/stories...5/story001.html
Could an enormous volcanic eruption have killed the dinosaurs?
Cardiff University -- The extinction of the dinosaurs -– thought to be caused by an asteroid impact some 65 million years ago –- was more likely to have been caused by a 'mantle plume' -– a huge volcanic eruption from deep within the earth's mantle, the region between the crust and the core of the earth.
This theory, already supported by a significant body of geologists and palaeontologists, is strengthened by new evidence to be presented at an international conference at Cardiff University on 11-12 September.
Research by an American earth scientist, Professor Gerta Keller and her team, suggests that a similar eruption under the Indian Ocean several million years before the extinction of the dinosaurs had a similarly devastating impact on the environment.
However, at this earlier time there is no evidence of any asteroid impact.
Her findings are based on analysis of microfossil assemblages, which were found inside cores that had been drilled deep into sediments on the ocean floor.
The eruptions that were responsible for these two extinction events were as a result of mantle plumes -– a phenomenon caused by rising hot mantle from deep within the earth.
Likened to the actions of a lava lamp, the mantle's heat causes it to rise and mushroom out; it then flattens causing the mantle to melt and erupt magma over the earth's surface and across an area of some 1,000 kilometres diameter.
These eruptions last between one and two million years and more than one million cubic kilometres of lava can be erupted in that time.
Today, we can witness seven huge remnants of such mantle plume activity. These are also known as 'hotspots' and are responsible for the volcanic activity on Iceland, the islands of Hawaii, Easter, Reunion, Tristan and Louisville as well as volcanism in the Afar region of Ethopia.
"Mantle plumes are literally a hot topic for debate," said conference organiser Dr Andrew Kerr of Cardiff University's School of Earth, Ocean and Planetary Sciences.
"They are a catalyst for the formation of ocean basins and fundamentally reshaping the earth's surfaces. The massive outpouring of lava, ashes, and gas can have significant effects on climate, which destabilises the environment and have the potential to dictate the course of evolution. It is likely that were it not for mantle plumes, mammals would not have become predominant, and humankind would not be here today.
"Bizarrely, amongst earth scientists, there is also a vocal minority who don't believe that mantle plumes exist at all. This conference is therefore an opportunity to address these issues and validity of the links between mantle plumes with the evolution of life by bringing together geophysicists, petrologists and palaeontologists." |
|
|
| MrSquirrel |
Ahh yes....The caldera volcano theory.
Saw a very interesting show on the discovery channel I believe about this a couple years ago.
I will try to look up the info I saw tomorrow when I get home from work.
On a side not occrider: The other shows on NK other than the "nuclear nightmare" one are also very very interesting. A 2 parter on the Korean War and a look at the suffering of children in NK (hidden camera footage contrasted with official tourist visits to Pyongyang etc.)
The caldera eruption show was very interesting. I think I watched it twice in one day :D
MrS |
|
|
| occrider |
| quote: | Originally posted by MrSquirrel
On a side not occrider: The other shows on NK other than the "nuclear nightmare" one are also very very interesting. A 2 parter on the Korean War and a look at the suffering of children in NK (hidden camera footage contrasted with official tourist visits to Pyongyang etc.)
MrS |
Ah yes, I believe I saw that NK special ... while we're on the topic of NK I might as well hijack my own thread:
| quote: |
China Sends Armed Forces to Monitor North Korean Border
By JOSEPH KAHN The New York Times
BEIJING, Sept. 15 Chinese armed forces have moved into new positions along the country's border with North Korea (news - web sites), charged with defending an 870-mile crossing that is often violated by hungry refugees from the isolated Communist state.
Chinese foreign ministry (news - web sites) officials confirmed in a statement issued this afternoon that troops from the People's Liberation Army had replaced police along the border, though they did not confirm Hong Kong news reports that the move involved as many as 150,000 soldiers.
The move marks a subtle but significant change in relations between the two Communist states, which fought together against the United States in the Korean War and still have a mutual defense treaty.
While Chinese officials described the new border arrangements as a routine adjustment, it comes at a time when Beijing has exerted fresh pressure on North Korea to abandon its nuclear weapons program. China is the main sponsor of multilateral negotiations involving North Korea, the United States and three other countries aimed at reaching a negotiated settlement to the Korean arms standoff.
The dispatch of army troops also suggests that China could be preparing for the possibility of conflict in the region, though analysts said they considered it highly unlikely that China intends to threaten Pyongyang militarily.
"I think this shows that China is getting more concerned about the overall state of affairs in North Korea and the refugee problem in particular," said Ma Dingsheng, a Chinese military analyst in Hong Kong. "But we are not seeing the kind of deployment you would see if China were contemplating military action."
He said the border troops were the type that guard China's boundaries in other sensitive areas, like the restive Western region of Xinjiang, and were not equipped with tanks or artillery.
The Korean border has been a source of consternation for China in recent years, as North Korea refugees have slipped over in increasingly greater numbers to escape poverty, famine and political repression. Groups devoted to helping the refugees say as many as 300,000 North Koreans live in northeastern China, often in constant fear of being captured and repatriated by Chinese police.
The flow of refugees reaches its peak in the winter months, when the Yalu River freezes and people can walk across the loosely patrolled region with little difficulty.
The Bush administration has pressed China to allow more North Koreans to flee across the border as a way of pressuring the Pyongyang regime of Kim Jong Il or even causing it to collapse. But Beijing has resisted those entreaties, and the deployment of troops suggests that it does not plan to relax its stance soon.
Though many North Koreans live and work in China unofficially, Beijing often rounds up refugees and sends them back to North Korea without following United Nations (news - web sites) guidelines on assessing whether they fled for political or economic reasons. By many accounts Pyongyang authorities severely punish those people when they return.
The foreign ministry statement said that border patrol duties had now been assigned to the army, replacing the police. Analysts said the troops would be taking over from the People's Armed Police, which is a quasi-military unit that performs border duties in some areas.
The statement said a similar adjustment had been made on part of China's border with Myanmar. It did not give a reason for the change in either location.
"It is a normal adjustment carried out after many years of preparation by the relevant parties," the statement said.
Chinese troop movements near North Korea and Myanmar have attracted attention in recent weeks. Several Hong Kong newspapers have reported that as many as 150,000 troops have been assigned to tighten security along the Korean border, as many soldiers as the United States has stationed in Iraq (news - web sites), but the estimates are unconfirmed.
|
Go China ... growing some balls. Unless they're mearly trying to stem the flow of hungry refugees ... then they're cocks. |
|
|
| MrSquirrel |
| quote: | Originally posted by occrider
Ah yes, I believe I saw that NK special ... while we're on the topic of NK I might as well hijack my own thread:
Go China ... growing some balls. Unless they're mearly trying to stem the flow of hungry refugees ... then they're cocks. |
Maybe they are preparing for a counter-strike against the "American Imperialists" when they reach the Yalu like Mao did in the original war.
I think though that it is the "cock" scenario. They don't want these refuges to get far rnough into the country to get to Beijing and jump the walls of a foreign embassy.
Back off the thread jack....I will try and find that info tomorrow I promise :D
MrS |
|
|
| rizen |
| no discovery, tlc or history channel talk... my lazy ass hasnt ordered cable to my new place :( |
|
|
| Sand Leaper |
| quote: | Originally posted by rizen
no discovery, tlc or history channel talk... my lazy ass hasnt ordered cable to my new place :( |
I never had cable in my entire life.I'm such a loser :( |
|
|
| Photo_bot_2k1 |
| terminators killed the dinosaurs |
|
|
| Izzy |
| quote: | Originally posted by Photo_bot_2k1
terminators killed the dinosaurs |
actually, i ate them all :eyes:
cool posts though (both topics, hehe) |
|
|
| tathi |
Correct me if i am wrong (my interest in dinasaurs has faded as i have grown older ;): Suffocation was the major cause of death of the dinasaurs, evidence of this is shown in the small percentage that survived the Cretaceous? period that did not die of asphyxiation, were able to exist with a much lower atmospheric oxygen level.
Suffocation (as a means of death) gives credibility to both the meteorite and volcano theory, and the volcano theory supports the previous mass extinction in the Permian? era
| quote: | | Go China ... growing some balls. Unless they're mearly trying to stem the flow of hungry refugees ... then they're cocks. |
China are to busy going after Taiwan |
|
|
| daffodil |
it seems to me as if there should be a lot more geological evidence if scientists wanted to bolster the asteroid theory. such evidence would include:
- a large enough crater
- higher concentrations of noxious gases in the sediment layers corresponding to the time period of dinosaur extinction
- fewer plant fossils at the time of dinosaur extinction, because plants would not be able to photosynthesize in the diminished sunlight that corresponded to global cooling.
i'm not sure what other evidence has been gathered to support the asteroid theory -- i'm trying to stay off of google to keep my procrastination to a minimum right now. looks as if the volcano theory could already be a step ahead though. |
|
|
| rizen |
| quote: | Originally posted by daffodil
- a large enough crater |
i remember a while back, a discovery or tlc special talking about the gulf of mexico being the crater of the astroid that wiped out the dinosaurs :conf: |
|
|
| occrider |
| quote: | Originally posted by daffodil
it seems to me as if there should be a lot more geological evidence if scientists wanted to bolster the asteroid theory. such evidence would include:
- a large enough crater
- higher concentrations of noxious gases in the sediment layers corresponding to the time period of dinosaur extinction
- fewer plant fossils at the time of dinosaur extinction, because plants would not be able to photosynthesize in the diminished sunlight that corresponded to global cooling.
i'm not sure what other evidence has been gathered to support the asteroid theory -- i'm trying to stay off of google to keep my procrastination to a minimum right now. looks as if the volcano theory could already be a step ahead though. |
Hehehe sorry to correct you ;), but actually some of that evidence does indeed exist. It is/was generally thought that the Yucatan peninsula in Mexico harbored the impact crater of the meteor thought to kill off the dinosaurs. The reason it is not as prevalent as say meteor crater in Arizona, is because of millions of years of limestone sediment buildup and because a portion of the impact crater is now a part of the gulf of mexico. Since the estimated size of the crater was 125 miles in diameter, the meteor was theorized to be 10 miles wide. Given the fact that the meteor struck an odd 65 million years or so ago, that corresponds quite nicely with the most recent mass exctinction (I think there were two or three in history) of the cretaceous period (about 65 million years ago) in which something like 70% of all life on Earth was extinguished. Including plants one can presume. I'm no geologist so I have no clue about noxious gasses being prevelant in sediment layers.
Tathi raises an interesting point about Dinosaurs perhaps suffocating rather than starving to death as the food supply diminishes. I hadn't quite heard that theory before, but I guess one way to tell would be to analyze fossil remains to determine whether there was a massive extincion in a matter of hours, or whether the extinction happened gradually over the course of days/months/years as the food supply dwindled. I dunno if scientists can carbon date fossils to that degree of accuracy. Or perhaps they can simply look to see if most fossil remains are in relative close proximity (they died in herds due to quick suffocation) or whether the fossil remains are spread out disjointly (they died one by one as they starved to death).
At any rate, I wouldn't be surprised if both happened at the same time. Given the volatile geological activity of the Earth at the time, perhaps an extinction sized asteroid collided with the Earth and set off a chain reaction of volcanic activity? It's been a while since I studied the topic. Wierd thing is, we studied all this in astronomy class ... not an earth sciences class hehe. |
|
|
|
|
