I'm not sure what I have to say about it, or what others might. I just thought this was interesting. http://www.cnn.com/2009/TECH/science/01/02/comet.diamonds/index.html [rquoter]Study: Diamonds link comet to mammal extinction Tiny diamonds found in the soil are "strong evidence" a comet exploded on or above North America nearly 13,000 years ago, leading to the extinction of dozens of mammal species, according to a study. The scientific report also suggests the cataclysm also reduced the population of the earliest people to inhabit the region and triggered a 1,300-year-long cold spell that stretched around the world. The heat generated by the extraterrestrial impact likely melted much of a glacier that once covered the Great Lakes region, sending a massive flood down the Mississippi River, the study said. According to the report, the cold waves of glacial runoff into the Gulf of Mexico shifted Atlantic Ocean currents, changing climate patterns throughout the world in a cooling period known as the Younger Dryas. "A rare swarm" of comets rained over North America about 12,900 years ago, sparking fires that produced choking, leading "to the extinction of a large range of animals, including mammoths, across North America," the report said. The study was conducted by a group of eight archaeologists and geologists from the universities of Oregon and California, Northern Arizona University, Oklahoma University and DePaul University. Their findings were published Friday in the journal Nature. The prehistoric humans known to have inhabited the continent at the time of the event -- hunters and gatherers dubbed the Clovis culture -- suffered a major decline in population in the aftermath, the scientists said. The scientists, studying layers of sediment dated to 12,900 years ago at six North American locations, including one directly on top of a Clovis site in Murray Springs, Arizona. Each layer was rich in nanodiamonds, which are produced under high-temperature, high-pressure conditions created by cosmic impacts, the report said. "The nanodiamonds that we found at all six locations exist only in sediments associated with the Younger Dryas Boundary layers, not above it or below it," said University of Oregon archaeologist Douglas Kennett. "These discoveries provide strong evidence for a cosmic impact event at approximately 12,900 years ago that would have had enormous environmental consequences for plants, animals and humans across North America." The other sites studied were in Bull Creek, Oklahoma; Gainey, Michigan and Topper, South Carolina, as well as Lake Hind, Manitoba; and Chobot, in the Canadian province of Alberta. [/rquoter]
Really interesting... Last night I watched a show I had DVR'd called The Day the Earth Nearly Died. It was about the extinction event that preceded the dinosaurs that was massive...they estimate that 90% of living things on the planet died out...and were trying to trace back the causes. Amazing stuff.
I think that's the Permian extinction. It was especially hard on marine species, with 96% of ocean life species going extinct. 250 million years ago...
That's an interesting hypothesis. My understanding was that the prevailing theory on the extinction of most of the North American mega fauna was due to hunting by early humans as things like giant sloths and giant Armadillos died out quickly after humans first arrived in the Americas.
Stuff like the Permian extinction make me wonder about how tenacious life is. Just wondering if the Earth were to suffer a possibly calamity as what befell Mars, the loss of the magnetic field and eventual loss of atmosphere, if the life on Earth would still manage to survive in some state.
Not for sure. One of the ideas I've heard is that Mars' core cooled down and solidified causing it to lose its magnetic field. Without its magnetic field the solar wind eventually stripped Mars of most of its atmosphere along with having most of its water boil off into space.
Yep, I have read that same theory, that there is a nuclear reactor at the center or core of each planet....and if it stops, life does too. DD
can the "nuclear reactor" shut off at any time? or is it rare to happen...i mean is earth gonna make it to the point until the sun dies? scary stuff to think about
I did some more reading about it and its not exactly a nuclear reactor but an electric generator, dynamo, that generates the magnetic field. In Mars' case the field might've been their at one point being caused by a an asteroid orbiting Mars but was shut off when the asteroid eventually crashed into Mars. http://www.newscientist.com/article...switched-marss-magnetic-field-on-and-off.html [rquoter]CAN you flip a planet's magnetic field on and off like a light switch? An asteroid could have done just that to Mars 4 billion years ago. Mars once had a magnetic field, which may have been driven by a dynamo formed from the convection of material in the core, much like the Earth's is today. Yet crater records suggest the Martian dynamo died quickly, over a few tens of thousands of years, something researchers struggle to explain. Now Jafar Arkani-Hamed of the University of Toronto, Canada, and colleagues say the gravitational tug of an orbiting asteroid may have powered a dynamo by pulling on the fluid in Mars's core. The team's lab and model simulations showed that an asteroid orbiting 75,000 kilometres above Mars could have maintained a dynamo for 400 million years, before the rock crashed into the planet and switched it off (Journal of Geophysical Research, DOI: 10.1029/2007JE002982). Some researchers are sceptical. While an asteroid might have had enough energy to churn fluid in the planet's core, much more energy is needed to set up the dynamo to begin with, according to David Stevenson of the California Institute of Technology in Pasadena. "It would be like looking at a boulder on top of a hill without asking what it took to get it there," he says. [/rquoter]
No rationalizing how scary an extinction event can be. They're just so big and powerful, so much inevitability to it that you really cant do anything about it. So if its your turn to go, at least its everyone else's too I know its years upon years of layered research to reach these conclusions. Sometimes its funny reading these things like they picked up some nanodiamonds laying in the dirt and said yeah by looking at this I can tell you what happened to mammoths and everything in the cosmos 13,000 years ago.
Why did this story remind me of that Cheech & Chong movie with the diamond field? The TV version I think.
The op diamond thing is interesting... seems like some seemingly hard evidence (pun intended), but stuff like the mars thing and other theories being discussed (permian, whatever) it's all a bit like religion to me. Someone trying to make a career out of theorization, finds one or two clues, then has a huge story as to what did or did not happen, or what is and what is not. I'm not discounting anything specifically (science OR religion), but I am saying that people sure know how to go places with just a little gas in the tank. Biggest journeys start with a small step I guess, I just don't like it when the would be traveller tries to tell everyone exactly what the destination is like right after he gets his shoes on or finds his keys. Speculation is interesting, though, as long as it's presented as such.
