Lava Flow May Have Caused Extinction 30
Pinhead writes "From MSNBC, it appears a new study suggests that a massive extinction that occurred 250 million years ago may not have been an asteroid but a large lava flow that spewed large amounts of poisonous gases in the air. This extinction led to the rise of the dinosaurs." Note that there are two different big extinctions: this first one occurred when plant life was mostly ferns, and all the continents were together in Pangaea. The later one is the one that everyone knows about, that wiped out the dinosaurs.
You know what this means! (Score:1)
A volcano might have affected humans too (Score:2)
Browse This Google search [google.com] for more information.
not just two mass extinctions... (Score:1)
There's been a lot more than just two mass extinctions over the history of the earth - there's evidence of events where up to 90% of existing species have disappeared scattered throughout the fossil record. Some of these have probably been caused by meteorite or comet impacts, others quite possibly by large geological events - massive lava outpourings can release enough CO2 into the atmoshpere to have a definite effect on world climate.
There's been a lot more than two (Score:3, Informative)
However it doesn't take a lot of imagination to realise that the abrupt changes in the rocks which have long guided geologists to divide geologic time into distinct epochs must be due to global changes in the ecology, especially in marine microorganisms
This overview [park.org] of the big five events and their causes shows them bracketed by a pair that led into the Cambrian explosion and a seemingly human induced one.
There is a lot of conjecture about causes for specific extinction events, IMNSHO mainly due to the growing human (and especially scientific) demand that causes be singular. Purported causes include extensive glaciation which is relatively easy to spot in the geological record, flood volcanism, which is a bit harder because it is relatively localised, and impacts, the most recent of which at least managed to leave a layer enriched with iridium and a large crater.
But even re that most recent dinosaur ending event there is still evidence that the Deccan Traps lava flood may have played a role, as there are persistent claims for impacts as well as Siberian lava flows around the time of the real biggie at the end of the Permian which this article focuses on.
Personally I'm leaning more and more towards a double whammy theory of mass extinction that would require some sustained global stress complemented by a more sudden knockout punch. And that doesn't get humanity off the hook.
Of more consequence for populist misinterpretations of Darwin's great insights is that it has needed the slate to be wiped almost clean many times before an opportunity arose for mammals, let alone humans, to rise to prominence.
As co-conspirators in the rise of imformation technology we should be able to see the importance of mass extinctions opening opportunities for those who may be better at innovation.
Re:There's been a lot more than two (Score:1)
(Isn't it always the way - as soon as you post something, someone comes along and says the same thing but in more detail and with links and references too...)
Heh :) (Score:3, Informative)
Seriously though - that the 250 m.y.a. extinction was not caused by a asteroid, but by volcanic activity in Siberia, has been the general opinion for quite some time.
first cock (Score:2)
A nice easy rhyme to remember
Cambrian - Ordivician - Silurian - Devonian - Carbiniferous - Permian - Triassic - Jurassic - Cretaceous - Tertiary - Quaternary
The dinousaur one was at the K-T Boundry (Cretaceous - Tertiary), end of the mesozoic IIRC.
The other big one (trilobites and about 90% of the earth - I think, its been a few years) was this one, and at the start of the mesozoic (Permian - Triassic)
Admit it, you're a geologist (Score:1)
Re:Admit it, you're a geologist (Score:2)
Lavaflow from MSNBC? (Score:2)
Rise of the dinosaurs (Score:2, Informative)
Re:Fairy tales (Score:1)
Re:Fairy tales (Score:2)
By the 1960s we were taught the Earth was 3.5 GYa, and now it's 4.5-4.6 as "conventional" wisdom.
BTW trees put on rings based on seasons, and many cases are recorded of multiple rings per annum.
link (Score:2)
Perhaps an asteroid AND a lava flow (Score:2)
The Chicxulub crater in Mexico is very nearly opposite the Deccan traps, which have both been fingered for the extinction of the dinosaurs 65 million years ago. There is also a possible large impact site in Australia of the right age, which would have been almost exactly opposite the Siberian Traps at the time of the Permian extinction 250 million years ago. On the planet Mercury there is a gigantic impact crater called the Caloris basin, which is also directly opposite "weird terrain" caused by focussed shockwaves.
Summarised from Terry Pratchett et al, "The Science of Discworld", pp 307-308, discussing mass extinctions, and the surprisingly essential role they appear to have played in the evolutionary history.
Drinking milk (Score:1)
Wouldn't a massive asteroid, say the likes of the one that cuased the creation of the Yucatan peninsula and the deepening of the Gulf of Mexico (discovered by no other than the Shoemaker-Levy dynamic duo based on satellite photos), cause some MAJOR seismic/techtonic/volcanic activity?
If someone punches you in the stomach while you are swallowing some milk, it's gonna shoot out of your mouth, nostrils, and possibly your ears.
Same thing with Earth. Punch it in the Yucatan and shit is gonna spray everywhere. Lava, dust, critters...everything.