Atlantis Online
March 29, 2024, 10:10:25 am
Welcome, Guest. Please login or register.

Login with username, password and session length
News: Were seafarers living here 16,000 years ago?
http://www.canada.com/victoriatimescolonist/news/story.html?id=34805893-6a53-46f5-a864-a96d53991051&k=39922
 
  Home Help Arcade Gallery Links Staff List Calendar Login Register  

My Take: What Really Killed the Dinosaurs?

Pages: [1]   Go Down
  Print  
Author Topic: My Take: What Really Killed the Dinosaurs?  (Read 154 times)
0 Members and 50 Guests are viewing this topic.
Jennifer Murdoch
Superhero Member
******
Posts: 5235



« on: September 27, 2009, 12:16:36 am »

My Take: What Really Killed the Dinosaurs?
Paleontologist Gerta Keller says the evidence is mounting that a titanic volcanic eruption ended the age of dinosaurs

After almost three decades of nearly unchallenged wisdom that a large impact on Yucatan caused the end-Cretaceous mass extinction, this theory is facing its most serious challenge from Deccan volcanism in India. Recent discoveries by volcanologists from the Institut de Physique du Globe de Paris, France, led by Vincent Courtillot show that the major phase of Deccan volcanism, or about 80 percent of the total 3,500-meter thick lava pile erupted over a very short time interval estimated at hundreds to thousands of years near the end of the Cretaceous. Even today these lava mountains cover an area of 200,000 square miles, about the size of France, but originally lava flows covered an area of 600,000 square miles, or the equivalent of California, Nevada, Arizona, New Mexico and Colorado combined. The longest lava flows known on Earth reached 800-1,000 km across India and out to the Gulf of Bengal.

Geologist Thierry Adatte, University of Lausanne, Switzerland, myself, and scientists A.N. Reddy and B.C. Jaiprakash from India’s Oil and Gas Corporation were able to link the mass extinction to these longest lava flows, which were recovered in quarries and deep wells of eastern India, buried between 1.5 to 2 miles below the surface. The four lava flows, separated by short intervals of time, caused catastrophic devastation. After the first lava flow over 50 percent of planktic foraminifera species disappeared and with each successive eruption more species disappeared so that by the last of the four lava flows the mass extinction was complete.
Report Spam   Logged

Share on Facebook Share on Twitter

Jennifer Murdoch
Superhero Member
******
Posts: 5235



« Reply #1 on: September 27, 2009, 12:17:12 am »

How did volcanism cause the mass extinction? Lava eruptions occurred in pulses lasting a decade or more and pouring out enormous quantities of lava along fissures in the Earth that spanned over hundreds of miles. High fire columns spouted from these fissures and lofted gas into the stratosphere (6.5 miles up) as lava flows spread sheet-like over vast areas across India causing extreme heating. As devastating as the actual lava flows were in India, even more deadly were the huge quantities of sulfur dioxide injected into the stratosphere causing acid rain and extreme global cooling. Similar climatic and environmental effects are predicted from the Chicxulub impact. The difference is that the quantity of sulfur dioxide gas injected from Deccan eruptions was 30 to 100 times larger than from the Chicxulub impact and therefore dwarfs the effects of this impact.

We can estimate the devastation caused by India’s volcanism based on historic records of small volcanic eruptions, such as the Laki eruption of Iceland in 1783-1784. This eruption lasted eight months, released 4.7 cubic miles of lava (19.6 cubic km) and injected 0.12 gigatons of sulfur dioxide, compared with more than 5,000 gigatons in India. In Iceland, the immediate effects of the Laki eruptions were 50 percent of livestock killed leading to famine, which killed about 25 percent of the human population. Acid poison rain fell from the sky, thick with ash, sulfur and salt, all the plants turned bright yellow, withered and died. Inhaling the sulfur dioxide gas caused victims to choke, the death rate rose all over Europe as a thick poison gas cloud spread. The sun turned blood red and 1783 became the hottest year with severe thunderstorms and hail as the heat got trapped below the haze. This was followed by the coldest most severe winter causing further deaths. The spring thaw brought floods. The disturbance continued into 1785. If the rather small Laki eruption caused such enormous upheaval over a short time, what would Deccan eruptions do, considering that they lasted thousands of years?
Report Spam   Logged
Jennifer Murdoch
Superhero Member
******
Posts: 5235



« Reply #2 on: September 27, 2009, 12:17:42 am »

The immediate effects would have been devastating in India and all over Asia as poison gas clouds spread and a thick haze covered the region spreading famine, disease and death. As acid rain fell from the sky thick with ash, sulfur and salt coating plants causing them to bleach, whither and die. Animals would suffer deaths from respiratory disease, and starvation. Heat trapped beneath the haze would result in extremely hot conditions killing further survivors. The extreme heat conditions would continue for as long as the eruptions lasted. Heat was followed by extreme cooling and acid rain as the atmosphere was washed out and the sulfur dioxide converted to sulfuric acid, thus causing further death and devastation on land and acidified the oceans killing off marine life. On land extreme cooling and acid rain would continue well after the volcanic eruptions, or until the gases are washed out of the atmosphere. But in the oceans it would take at least 1,000 years for normal conditions to recover because of the slow oceanic turnover rate.

Deccan volcanism, its high intensity and high volume of eruptions over a very short time interval set the perfect conditions for global devastation and the mass extinctions at the end of the Cretaceous. This should not be surprising. The largest mass extinction in Earth’s history, which killed off 80 percent of life on Earth, occurred 251 million years ago at the end of the Permian Period and is directly linked to massive volcanism in Siberia.

Article posted February 17, 2009

http://dsc.discovery.com/earth/my-take/0902/gerta-keller.html
Report Spam   Logged
Pages: [1]   Go Up
  Print  
 
Jump to:  

Powered by EzPortal
Bookmark this site! | Upgrade This Forum
SMF For Free - Create your own Forum
Powered by SMF | SMF © 2016, Simple Machines
Privacy Policy