Diamond Clues To Beasts' Demise

[Guest Nicholas]

Auspex mentioned this theory once before, I have also heard about it in passing and stumbled upon this article over my morning tea. Enjoy...

The controversial idea that space impacts may have wiped out woolly mammoths and early human settlers in North America has received new impetus.

Find the article HERE!

[Guest bmorefossil]

"I'm still in a wait-and-see mode," added Dr Severinghaus. I couldnt say it better myself. There are so many theories being thrown out there you can only wait until they can prove what they are saying.

[Guest solius symbiosus]

this topic is related to THIS thread.

[Guest Nicholas]

this topic is related to THIS thread.

I decided to give this topic its own thread merely because it involves the species extinction theory. Thanks for bringing it in though.

[Guest bmorefossil]

I decided to give this topic its own thread merely because it involves the species extinction theory. Thanks for bringing it in though.

and its a different article right?

[Guest Nicholas]

and its a different article right?

The same but different.

[Guest bmorefossil]

The same but different.

well i know that most of the information is the same and its on the same event but they are two different articles.

[Guest solius symbiosus]

^^ They are different writes ups, but the one from this thread, and the two links in the other thread are based upon a paper that was published Friday on the AAAS web site.

The abstract:

Science 2 January 2009:

Vol. 323. no. 5910, p. 94

DOI: 10.1126/science.1162819

Nanodiamonds in the Younger Dryas Boundary Sediment Layer

D. J. Kennett,1* J. P. Kennett,2 A. West,3 C. Mercer,4 S. S. Que Hee,5 L. Bement,6 T. E. Bunch,7 M. Sellers,7 W. S. Wolbach8

We report abundant nanodiamonds in sediments dating to 12.9 ± 0.1 thousand calendar years before the present at multiple locations across North America. Selected area electron diffraction patterns reveal two diamond allotropes in this boundary layer but not above or below that interval. Cubic diamonds form under high temperature-pressure regimes, and n-diamonds also require extraordinary conditions, well outside the range of Earth's typical surficial processes but common to cosmic impacts. N-diamond concentrations range from {asymp}10 to 3700 parts per billion by weight, comparable to amounts found in known impact layers. These diamonds provide strong evidence for Earth's collision with a rare swarm of carbonaceous chondrites or comets at the onset of the Younger Dryas cool interval, producing multiple airbursts and possible surface impacts, with severe repercussions for plants, animals, and humans in North America.

[Guest bmorefossil]

ah ok thanks solius

[Guest Nicholas]

MORE!

[Guest solius symbiosus]

Comet impact theory disproved

New data, published today, disproves the recent theory that a large comet exploded over North America 12,900 years ago, causing a shock wave that travelled across North America at hundreds of kilometres per hour and triggering continent-wide wildfires.

Dr Sandy Harrison from the University of Bristol and colleagues tested the theory by examining charcoal and pollen records to assess how fire regimes in North America changed between 15 and 10,000 years ago, a time of large and rapid climate changes.

Their results provide no evidence for continental-scale fires, but support the fact that the increase in large-scale wildfires in all regions of the world during the past decade is related to an increase in global warming.

Fire is the most ubiquitous form of landscape disturbance and has important effects on climate through the global carbon cycle and changing atmospheric chemistry. This has triggered an interest in knowing how fire has changed in the past, and particularly how fire regimes respond to periods of major warming.

The end of the Younger Dryas, about 11,700 years ago, was an interval when the temperature of Greenland warmed by over 5°C in less than a few decades. The team used 35 records of charcoal accumulation in lake sediments from sites across North America to see whether fire regimes across the continent showed any response to such rapid warming.

They found clear changes in biomass burning and fire frequency whenever climate changed abruptly, and most particularly when temperatures increased at the end of the Younger Dryas cold phase. The results are published today [26 January] in the Proceedings of the National Academy of Science.

Understanding whether rapid changes in climate have caused wild fires in the past will help understand whether current changes in global temperatures will cause more frequent fires at the present time. Such fires have a major impact on the economy and health of the population, as well as feeding into the increase in global warming.

http://www.eurekalert.org/pub_releases/2009-01/uob-cit012609.php

[mommabetts]

Good read guys, thanks for sharing.