Jan 22, 2020 08:44 PM
(This post was last modified: Jan 23, 2020 01:58 AM by C C.)
The Mount Vesuvius eruption was so hot, one man’s brain turned to glass
https://arstechnica.com/science/2020/01/...-to-glass/
EXCERPT: When Mount Vesuvius erupted in 79 CE, the heat was so extreme in some places that it vaporized body fluids and exploded the skulls of several inhabitants unable to flee in time. Now, archaeologists have determined that the heat also fused brain tissue into glass in one victim. The discovery is described in a new short paper in the New England Journal of Medicine.
[...] we have additional evidence that extreme heat killed many victims. Petrone and several colleagues have completed an analysis of one victim's skull in particular, first excavated in the 1960s from Herculaneum. The body was found on a wooden bed, buried in volcanic ash, and there was evidence of brain matter remains in the skull. According to Petrone et al., usually such brain matter would be "saponified" by the extreme heat—that is, it turned to soap (glycerol and fatty acids). But this particular victim's brain matter had been vitrified, i.e., fused into glass.
Co-author Piero Pucci of CEINGE analyzed the glassy material inside the skull and found traces of fatty acids common to the triglycerides in the human brain, along with human hair components. No such substances were found in the surrounding ash or charcoal at the site where the skull was found, indicating that the material was most likely brain matter... (MORE - details)
World's oldest asteroid strike could have triggered global thaw
https://theconversation.com/we-found-the...haw-130192
EXCERPT (Timmons Erickson): The world’s oldest remaining asteroid crater is at a place called Yarrabubba, southeast of the town of Meekatharra in Western Australia. Our new study puts a precise age on the cataclysmic impact – showing Yarrabubba is the oldest known crater and dating it at the right time to trigger the end of an ancient glacial period and the warming of the entire planet.
Yarrrabubba holds the eroded remnants of a crater 70 kilometres wide that was first described in 2003, based on minerals at the site that showed unique signs of impact. But its true age was not known. The Yarrabubba crater is about 70 kilometres across. We studied tiny “impact-shocked” crystals found at the site, which show the crater formed 2.229 billion years ago (give or take 5 million years).
[...] the geological record shows the Earth had glacial ice before the time of the impact – but afterwards, ice disappeared for hundreds of millions of years. Was the Yarrabubba impact a trigger for global climate change? ... To understand the effect of the impact on an ice-covered world, we used computer models based on the physics of shockwaves to estimate how much ice would end up in the atmosphere as water vapour. As it turns out, it’s quite a lot.
Our models show that if the Yarrabubba asteroid hit an ice sheet 5 kilometres thick (not an unreasonable estimate), more than 200 billion tons of water vapour would be ejected into the atmosphere. That’s about 2% of the total amount of water vapour in today’s atmosphere, but would have been a much bigger fraction back then.
Water vapour is a serious greenhouse gas. It’s responsible for about half of the heat absorption from solar radiation today. Global climate models don’t yet exist for the Proterozoic Earth, so we don’t yet know for sure if the Yarrabubba impact pushed the planet past a tipping point that led to more warming and the end of a possible Snowball Earth. (MORE - details)
https://arstechnica.com/science/2020/01/...-to-glass/
EXCERPT: When Mount Vesuvius erupted in 79 CE, the heat was so extreme in some places that it vaporized body fluids and exploded the skulls of several inhabitants unable to flee in time. Now, archaeologists have determined that the heat also fused brain tissue into glass in one victim. The discovery is described in a new short paper in the New England Journal of Medicine.
[...] we have additional evidence that extreme heat killed many victims. Petrone and several colleagues have completed an analysis of one victim's skull in particular, first excavated in the 1960s from Herculaneum. The body was found on a wooden bed, buried in volcanic ash, and there was evidence of brain matter remains in the skull. According to Petrone et al., usually such brain matter would be "saponified" by the extreme heat—that is, it turned to soap (glycerol and fatty acids). But this particular victim's brain matter had been vitrified, i.e., fused into glass.
Co-author Piero Pucci of CEINGE analyzed the glassy material inside the skull and found traces of fatty acids common to the triglycerides in the human brain, along with human hair components. No such substances were found in the surrounding ash or charcoal at the site where the skull was found, indicating that the material was most likely brain matter... (MORE - details)
World's oldest asteroid strike could have triggered global thaw
https://theconversation.com/we-found-the...haw-130192
EXCERPT (Timmons Erickson): The world’s oldest remaining asteroid crater is at a place called Yarrabubba, southeast of the town of Meekatharra in Western Australia. Our new study puts a precise age on the cataclysmic impact – showing Yarrabubba is the oldest known crater and dating it at the right time to trigger the end of an ancient glacial period and the warming of the entire planet.
Yarrrabubba holds the eroded remnants of a crater 70 kilometres wide that was first described in 2003, based on minerals at the site that showed unique signs of impact. But its true age was not known. The Yarrabubba crater is about 70 kilometres across. We studied tiny “impact-shocked” crystals found at the site, which show the crater formed 2.229 billion years ago (give or take 5 million years).
[...] the geological record shows the Earth had glacial ice before the time of the impact – but afterwards, ice disappeared for hundreds of millions of years. Was the Yarrabubba impact a trigger for global climate change? ... To understand the effect of the impact on an ice-covered world, we used computer models based on the physics of shockwaves to estimate how much ice would end up in the atmosphere as water vapour. As it turns out, it’s quite a lot.
Our models show that if the Yarrabubba asteroid hit an ice sheet 5 kilometres thick (not an unreasonable estimate), more than 200 billion tons of water vapour would be ejected into the atmosphere. That’s about 2% of the total amount of water vapour in today’s atmosphere, but would have been a much bigger fraction back then.
Water vapour is a serious greenhouse gas. It’s responsible for about half of the heat absorption from solar radiation today. Global climate models don’t yet exist for the Proterozoic Earth, so we don’t yet know for sure if the Yarrabubba impact pushed the planet past a tipping point that led to more warming and the end of a possible Snowball Earth. (MORE - details)