Archaeologica.org

http://www.sciencedaily.com/releases/20 ... 141707.htm

Roy.

As I understand it the actual event that caused that 'nuclear winter' is disputed as well. The idea seems to be gaining ground that the Deccan flows were the primary catalyst. Not that Yucatan comet. And there is a chronological gap between those 2 events too. Maybe only due to different dating methods, but needs to be resolved in any case, of course.

I'm not on my home computer so please excuse the lack of easy links.

We now know about the Shiva Impact, and the causative effects of both the Chicxulub impact and the Shiva impact on the Deccan Traps.

The whole of the Shiva Affair is going to be one of the saddest stories in the history of science if it is ever written.

Thus it is not a case of Paradigm Lost, but rather Paradigm Refined. No longer one impact, but rather two.

That's a bonafide cliff hanger! Can't wait for you to expand on that, E.P. The suspense is killing me.

Heaman and colleagues used a new direct-dating method called U-Pb (uranium-lead) dating. A laser beam unseats minute particles of the fossil, which then undergo isotopic analysis.

Assuming, just for the sake of argument, that U-Pb is more accurate than other methods, why not examine other fossils from the period and see if the findings are confirmed. There is always a possibility that U-Pb is less accurate rather than more but without further testing I don't see how a definitive answer can be reached.

Minimalist wrote:

Heaman and colleagues used a new direct-dating method called U-Pb (uranium-lead) dating. A laser beam unseats minute particles of the fossil, which then undergo isotopic analysis.

Assuming, just for the sake of argument, that U-Pb is more accurate than other methods, why not examine other fossils from the period and see if the findings are confirmed. There is always a possibility that U-Pb is less accurate rather than more but without further testing I don't see how a definitive answer can be reached.

Hi Min -

The suspense will have to continue for a while.

The time difference between the Chicxulub Impact and the Shiva Impact is set at 300,000 to 700,000 years, at the very limit of isotope based dating techniques. To give you some idea of isotope dating accuracies, dates for the Chicxulub Impact itself vary by 1,000,000-2,000,000 years; and by the way, it was a comet that hit, not an asteroid.

I myself am working on another major recent North American impact, and that will have top priority after my computer returns. But they're calling for somewhere between more snow and another blizzard, so there is nothing to do but be patient.

E.P. Grondine wrote:The time difference between the Chicxulub Impact and the Shiva Impact is set at 300,000 to 700,000 years, at the very limit of isotope based dating techniques. To give you some idea of isotope dating accuracies, dates for the Chicxulub Impact itself vary by 1,000,000-2,000,000 years; and by the way, it was a comet that hit, not an asteroid.

The jury is still out on that, I understand.
Besides, the Chicxulub and Shiva impacts may both well have been part of the same 'cloud' of space rocks, or of the same disintegrating space rock. As space rocks tend to do within planetary gravity fields (e.g. the comet Shoemaker-Levy's impact on Jupiter). The current timing/dating technology is far too imprecise to be certain they were impacts with separate origins.

RS -

Researchers have recovered a "kt-fossil" meteorite, and the impactors were most likely cometary.
The timing also indicates this.
Whether the impactors were large fragements of the same comet or separate comets is not known.

E.P. Grondine wrote:RS -

Researchers have recovered a "kt-fossil" meteorite, and the impactors were most likely cometary.

Pray, how does finding a meteorite lead to the conclusion that another impactor was (most likely) cometary? The one is, per definition a hard space rock, while the great majority of the other is, afaik, considered to be 'dirty snowballs'... So where is the connection between the two?

The timing also indicates this.

I thought we had just covered the subject of imprecise dating! So I fail to see how "the timing" indicates anything at all.

Whether the impactors were large fragements of the same comet or separate comets is not known.

Exactly.
And also the assumptions that they were a) impacts (plural), and b) comets are purely speculative. Read: wishful thinking, afaic. And since we are speculating: I'm currently a supporter of the hypothesis that the Deccan Traps were the result of vast volcanic eruptions. Like a percolating magma mantle. Of a magnitude that is hard to comprehend for us today, but which might be comparable in scale to what the super volcano under Yellowstone might show if it erupted. Some projections indicate that event might cover two thirds of the continental US with lava flows. The Yellowstone Traps.

Rokcet Scientist wrote:

E.P. Grondine wrote:RS -

Researchers have recovered a "kt-fossil" meteorite, and the impactors were most likely cometary.

Pray, how does finding a meteorite lead to the conclusion that another impactor was (most likely) cometary? The one is, per definition a hard space rock, while the great majority of the other is, afaik, considered to be 'dirty snowballs'... So where is the connection between the two?

The timing also indicates this.

I thought we had just covered the subject of imprecise dating! So I fail to see how "the timing" indicates anything at all.

Whether the impactors were large fragements of the same comet or separate comets is not known.

Exactly.
And also the assumptions that they were a) impacts (plural), and b) comets are purely speculative. Read: wishful thinking, afaic. And since we are speculating: I'm currently a supporter of the hypothesis that the Deccan Traps were the result of vast volcanic eruptions. Like a percolating magma mantle. Of a magnitude that is hard to comprehend for us today, but which might be comparable in scale to what the super volcano under Yellowstone might show if it erupted. Some projections indicate that event might cover two thirds of the continental US with lava flows. The Yellowstone Traps.

RS, regarding your points a and b, there's too much stupidty in the world to take time to deal with idiots one by one.
But to sum up quickly:
a) big holes in ground
b) timing, impactites

Whipple changed his view:Comets are not dirty snowballs - it is better to think of them as icy dirt balls.

Look up Shiva, and you'll learn how Chicxulub and Shiva set off the Deccan Traps.

In the past, when Yellowstone has erupted, it has laid down a pyroclastic ash layer.

It is likely we will have plenty of warning of an eruption there.

E.P. Grondine wrote:

Rokcet Scientist wrote:

E.P. Grondine wrote:RS -

Researchers have recovered a "kt-fossil" meteorite, and the impactors were most likely cometary.

Pray, how does finding a meteorite lead to the conclusion that another impactor was (most likely) cometary? The one is, per definition a hard space rock, while the great majority of the other is, afaik, considered to be 'dirty snowballs'... So where is the connection between the two?

The timing also indicates this.

I thought we had just covered the subject of imprecise dating! So I fail to see how "the timing" indicates anything at all.

Whether the impactors were large fragements of the same comet or separate comets is not known.

Exactly.
And also the assumptions that they were a) impacts (plural), and b) comets are purely speculative. Read: wishful thinking, afaic. And since we are speculating: I'm currently a supporter of the hypothesis that the Deccan Traps were the result of vast volcanic eruptions. Like a percolating magma mantle. Of a magnitude that is hard to comprehend for us today, but which might be comparable in scale to what the super volcano under Yellowstone might show if it erupted. Some projections indicate that event might cover two thirds of the continental US with lava flows. The Yellowstone Traps.

RS, regarding your points a and b, there's too much stupidty in the world to take time to deal with idiots one by one.
But to sum up quickly:
a) big holes in ground
b) timing, impactites

Really?
Then where is the "big hole in the ground" that the supposed YD impact created?
And how does totally imprecise, unreliable timing/dating prove anything?
And how can any 'impactites' be linked to any specific, but un-proven (thus hypothetical) impact?
Sorry, but as far as I can see there isn't a sensible, logical explanation, supported by evidence.
I call that: speculation.

Does anybody here want to pay me for straightening RS out?

http://gsa.confex.com/gsa/2009AM/finalp ... 160197.htm
http://www.depts.ttu.edu/communications ... nosaur.php
(This is from 2006. If Benny had not taken the Cambridge Conference over to AGW scepticism in 2004, this discussion here would not be necessary. If you think I'm bitter, you're right.)
http://abob.libs.uga.edu/bobk/ccc/cc020403.html
http://www.staff.livjm.ac.uk/spsbpeis/C ... e-2006.htm

http://timesofindia.indiatimes.com/home ... 208389.cms
http://74.6.238.254/search/srpcache?ei= ... x5zi23tg--

http://www.astrobio.net/exclusive/1281/ ... k-t-impact
(Note especially the actions of the oil companies)
http://nitishpriyadarshi.blogspot.com/2 ... chive.html

The best summary:
http://www.economist.com/node/14698363

RS, a far as the YD event goes, you have simply wasted my time here, time I could have spent working on it. In the future I may insist that you buy a copy of "Man and Impact in the Americas" and donate it to a library in exchange for me clarifying things for you.

E.P. Grondine wrote:Does anybody here want to pay me for straightening RS out?

http://gsa.confex.com/gsa/2009AM/finalp ... 160197.htm
http://www.depts.ttu.edu/communications ... nosaur.php
(This is from 2006. If Benny had not taken the Cambridge Conference over to AGW scepticism in 2004, this discussion here would not be necessary. If you think I'm bitter, you're right.)
http://abob.libs.uga.edu/bobk/ccc/cc020403.html
http://www.staff.livjm.ac.uk/spsbpeis/C ... e-2006.htm

http://timesofindia.indiatimes.com/home ... 208389.cms
http://74.6.238.254/search/srpcache?ei= ... x5zi23tg--

http://www.astrobio.net/exclusive/1281/ ... k-t-impact
(Note especially the actions of the oil companies)
http://nitishpriyadarshi.blogspot.com/2 ... chive.html

The best summary:
http://www.economist.com/node/14698363

RS, a far as the YD event goes, you have simply wasted my time here, time I could have spent working on it. In the future I may insist that you buy a copy of "Man and Impact in the Americas" and donate it to a library in exchange for me clarifying things for you.

It is my pleasure E.P.
Maybe it's time you claimed your rightful place among the gods. I, for one, will staunchly support your bid all the way, of course. It's high time your razorsharp mind is perceived and fully recognized for what it is!
A double-edged sword.

Rokcet Scientist wrote:

E.P. Grondine wrote:RS, a far as the YD event goes, you have simply wasted my time here, time I could have spent working on it. In the future I may insist that you buy a copy of "Man and Impact in the Americas" and donate it to a library in exchange for me clarifying things for you.

It is my pleasure E.P.

I know.

Rokcet Scientist wrote: Maybe it's time you claimed your rightful place among the gods. I, for one, will staunchly support your bid all the way, of course. It's high time your razorsharp mind is perceived and fully recognized for what it is!
A double-edged sword.

If they want to give me a Nobel Prize or a Pulitzer, that's up to them.
I don't think they'll be asking you for your opinion, RS.

E.P. Grondine wrote:If they want to give me a Nobel Prize or a Pulitzer, that's up to them.

Don't hold your breath.