It’s possible that I shall make an ass of myself. But in that case one can always get out of it with a little dialectic. I have, of course, so worded my proposition as to be right either way (K.Marx, Letter to F.Engels on the Indian Mutiny)
Wednesday, November 24, 2021
Great Barrier Reef 'gives birth' in massive coral spawning event
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Ecologists hopeful after climate-related bleaching during
heat waves in 2016, 2017
The Associated Press ·
Corals produce billions of offspring by casting sperm and eggs into the Pacific Ocean off the Queensland state coastal city of Cairns, Australia, on Tuesday, Nov. 23, 2021. Australia's Great Barrier Reef is spawning in an explosion of colour as the World Heritage-listed natural wonder recovers from life-threatening coral bleaching episodes. (Gabriel Guzman/Calypso Productions/The Associated Press)
Australia's Great Barrier Reef is spawning in an explosion of colour as the World Heritage-listed natural wonder recovers from life-threatening coral bleaching episodes.
Scientists on Tuesday night recorded the corals producing billions of offspring by casting sperm and eggs into the Pacific Ocean off the Queensland state coastal city of Cairns.
The annual spawning event lasts for two or three days.
The network of 2,500 reefs covering 348,000 square kilometres (134,000 square miles) suffered significantly from coral bleaching caused by unusually warm ocean temperatures in 2016, 2017 and last year. The bleaching damaged two-thirds of the coral.
Gareth Phillips, a marine scientist with Reef Teach, a tourism and educational business, is studying the spawning as part of a project to monitor the reef's health.
"It is gratifying to see the reef give birth," Phillips said in a statement on Wednesday. "It's a strong demonstration that its ecological functions are intact and working after being in a recovery phase for more than 18 months."
"The reef has gone through its own troubles like we all have, but it can still respond — and that gives us hope. I think we must all focus on the victories as we emerge from the pandemic," he said.
3 white men guilty of murdering Black man Ahmaud Arbery, WHITE Georgia jury finds
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Arbery's killing in Georgia last year became part of a larger
national reckoning on racial injustice
The Associated Press ·
From left, Travis McMichael, his father, Gregory McMichael, and William 'Roddie' Bryan Jr., are seen in a combination of booking photos provided by the Glynn County, Ga., Detention Center. All three men were convicted on Wednesday of murdering Ahmaud Arbery in February 2020. (Glynn County Detention Center/The Associated Press)
All three white men charged in the death of Ahmaud Arbery — a 25-year-old Black man who was chased and shot in a Georgia neighbourhood in February 2020 — were convicted of murder Wednesday in the fatal shooting that became part of a larger national reckoning on racial injustice.
The convictions for Greg McMichael, son Travis McMichael and neighbour William "Roddie" Bryan came after jurors deliberated for about 10 hours. The men face minimum sentences of life in prison. It is up to the judge to decide whether that comes with or without the possibility of parole.
Travis McMichael stood for the verdict, his lawyer's arm around his shoulder. At one point, McMichael lowered his head to his chest. After the verdicts were read, as he stood to leave, he mouthed "love you" to his mother, who was in the courtroom.
Moments after the verdicts were announced, Arbery's father, Marcus Arbery Sr., was seen crying and hugging supporters outside the courtroom.
"He didn't do nothing," the father said, "but run and dream."
Ahmaud Arbery, 25, was killed while out jogging in the port city of Brunswick, Ga., on Feb. 23, 2020. (Marcus Arbery/Handout via Reuters)
The McMichaels grabbed guns and jumped in a pickup truck to pursue the 25-year-old Black man after seeing him running in their neighbourhood outside the Georgia port city of Brunswick in February 2020. Bryan joined the pursuit in his own pickup and recorded cellphone video of Travis McMichael fatally shooting Arbery.
Though prosecutors did not argue that racism motivated the killing, federal authorities have charged them with hate crimes, alleging that they chased and killed Arbery because he was Black. That case is scheduled to go to trial in February.
Shooting captured on video
The jury sent a note to Superior Court Judge Timothy Walmsley soon after returning to court Wednesday morning asking to view two versions of the shooting video — the original and one that investigators enhanced to reduce shadows — three times apiece.
Jurors returned to the courtroom to see the videos and listen again to the 911 call one of the defendants made from the bed of a pickup truck about 30 seconds before the shooting.
The disproportionately white jury received the case around midday Tuesday and spent about six hours deliberating before adjourning without a verdict.
People react outside the Glynn County Courthouse after the jury reached a guilty verdict in the trial of the three men in Brunswick, Ga., on Wednesday. (Marco Bello/Reuters)
The McMichaels told police they suspected Arbery was a fleeing burglar when they armed themselves and jumped in a pickup truck to chase him. Bryan joined the pursuit when they passed his house and recorded cellphone video of Travis McMichael blasting Arbery at close range with a shotgun as Arbery threw punches and grabbed for the weapon.
On the 911 call the jury reviewed, Greg McMichael tells an operator: "I'm out here in Satilla Shores. There's a Black male running down the street."
He then starts shouting, apparently as Arbery is running toward the McMichael's idling truck with Bryan's truck coming up behind him: "Stop right there! Damn it, stop! Travis!" Gunshots can be heard a few second later.
Multiple charges for each defendant
The graphic video of the shooting death leaked online two months later, and the Georgia Bureau of Investigation took over the case and arrested the three men. Each of them was charged with murder and other crimes.
Defence attorneys contended the McMichaels were attempting a legal citizen's arrest when they set off after Arbery, seeking to detain and question him as a suspected burglar after he was seen running from a nearby home under construction.
Travis McMichael testified that he shot Arbery in self-defence. He said Arbery turned and attacked with his fists while running past the idling truck where Travis McMichael stood with his shotgun.
Prosecutors said there was no evidence Arbery had committed crimes in the defendants' neighbourhood. He had enrolled at a technical college and was preparing at the time to study to become an electrician like his uncles
CANADA
Conservatives advance challenge of ruling imposing House vaccine mandate
OF COURSE THEY DO THEY ARE THEIR OWN SPECIAL INTEREST GROUP
CTVNews.ca Online Politics Producer Published Tuesday, November 23, 202
OTTAWA -- The Conservatives have advanced their promised challenge of the ruling that imposed the House of Commons vaccine mandate.
Chief opposition whip Blake Richards raised the question of privilege on Tuesday, in one of a series of Conservative concerns raised over in their view, their rights as MPs to do their jobs are being infringed upon.
“This question of privilege doesn't relate in any way to disputing vaccines, or their very vital role in conquering the COVID 19 pandemic… What I'm questioning here is the jurisdiction of the board to be able to make that decision,” Richards said in the House of Commons, going on to cite sections of the parliamentary rulebooks in making his case.
At issue for the Conservatives is the “improper conduct and precedent set” by the Board of Internal Economy (BOIE) in deciding to implement the mandate ahead of Parliament’s return, during a closed-door meeting. The board is a long-standing cross-party committee of nine MPs in House leadership roles, including Conservatives.
“I believe that the Board of Internal Economy decision represents a major breach of the ancient privileges of this House, and in fact could set a very troublesome precedent,” Richards said, adding that it’s electors and not MPs who should be deciding who can and cannot enter the House.
The rules state that in order to enter Hill buildings, all MPs and their staff, as well as all others who work on the Hill, either have to be fully vaccinated or have a valid medical “contraindication.” In order to get inside, those with exemption have to show a recent negative test result to the House authorities who have been put in charge of confirming who is cleared to come onto the premises.
Under these parameters, only those who are unwilling to be vaccinated but not medically exempt would be unable to enter.
With the exception of a few MPs, including one who currently has COVID-19, the entire Conservative caucus was present for the opening day of the new Parliament, meaning they all have either been vaccinated or, as Leader Erin O’Toole told CTV News, “in some limited circumstance” have a medical exemption.
O’Toole had signalled back in October that this challenge was coming, amid questions at the time over how many of his caucus members remained unvaccinated.
O’Toole has said that all of his members will “respect and abide by” the rules, before and after the Speaker rules on this matter.
Re-elected House Speaker Anthony Rota told MPs he will consider the matter and get back to the House at a later date with a decision. “I believe I have enough information to determine whether it's a prima facie case,” Rota, who is chair of the BOIE, said.
If Rota finds MPs’ privileges have been breached, Richards said his party would be proposing a motion “which would allow this House directly to pronounce itself on a vaccination or test mandate for members to access the precinct.”
“Some may say that the board's decision should be upheld because it's about safety, and I agree that in pandemic times it is right that we should take appropriate precautions. However, that does not mean the rights of Parliament should just be tossed out,” said Richards.
All MPs in the Liberal, Bloc Quebecois, NDP, and Green caucuses are fully vaccinated against COVID-19 and fully supportive of the mandate, so it remains to be seen how far the Conservative challenge will get.
Responding to Richard’s concerns, MPs from these parties who are also on the board voiced opposition to the Conservatives’ position.
Bloc Quebecois whip Claude DeBellefeuille called the mandate necessary given the current pandemic circumstances, and defended the authority that the Board has to make these kinds of rulings.
“This Parliament and previous parliaments have given specific instructions and bylaws to the board… to quote ‘make policy decisions to govern the use of funds, goods, services, and premises for the House, its committees, and members,’” said NDP House leader Peter Julian.
Julian also referenced the risk MPs pose both to their colleagues and their constituents given their high-travelling jobs and frequent interactions with the public.
The NDP has previously suggested that the Conservatives are out of touch for thinking there should be one set of rights for them as there are for all other Canadian adults looking to dine-in or board a plane.
“I don’t see a substance behind a question of privilege on this basis, I think this is smart, prudent public policy that was put into place by the Board of Internal Economy and it is something that should be upheld,” Julian said.
Others used the debate to bring up their discomfort with the ongoing lack of transparency from the Conservatives when it comes to being forthright about who in their caucus may be unvaccinated.
“I do not feel safe to use the opposition lobby, it's overcrowded. Even with masks we need to maintain physical distance, we need to be careful and I'm particularly vulnerable and feel vulnerable in that space, as I'm not confident that all the other people sharing it are double vaccinated,” said Green Party MP Elizabeth May. “I feel my privileges to do my work as a member of Parliament are impeded by not being able to use the opposition lobby until matters of public health and safety are completely and rigorously observed in this place.”
As part of a forthcoming motion to re-impose hybrid sittings that would see physical distancing and virtual proceedings return to the House, the government is looking to beef up the language around what would qualify as a valid medical exemption.
This move comes after concerns were raised that if there are multiple Conservatives with exemptions, it would be in Government House Leader Mark Holland’s view, “statistically improbable.”
The motion would update the board ruling to clarify that “reasons for medical exemptions follow the guidance from the Ontario Ministry of Health document entitled ‘Medical Exemptions to COVID-19 Vaccination’ and the National Advisory Committee on Immunization (NACI).”
The government motion is expected to be tabled and debated on Wednesday. The Conservatives are against reviving virtual proceedings, arguing that the Liberals have used them to evade accountability.
British Columbia
Wet'suwet'en pipeline opposition leader released with conditions
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Sleydo' Molly Wickham must stay 75m away from Coastal GasLink worksites and equipment
Sleydo' Molly Wickham embraces supporters after being released from Prince George Regional Correctional Centre Tuesday evening. (Andrew Kurjata/CBC)
A key leader in the fight against the Coastal GasLink pipeline in northwestern B.C. has been released from jail with the condition she not interfere with construction of the project.
Sleydo', also known as Molly Wickham, is free to return to her home territory in northwestern B.C. and engage in fishing, hunting, trapping and cultural practices, so long as she stays 75 meters away from Coastal GasLink worksites and equipment.
It is a stronger condition than that given to other Wet'suwet'en members who were released on the condition they stay at least 10 meters away from worksites and equipment.
Lawyers for Coastal GasLink argued Sleydo' should not be allowed into a court-ordered exclusion zone of the pipeline at all, contending that she has continuously stated her intention to take steps to stop construction and encouraged others to do the same.
Justice Marguerite Church of the Supreme Court of B.C. said such a broad ruling would interfere with the rights of Sleydo' to practice her culture as a Wet'suwet'en woman, and felt the 75 meter limitation was an acceptable compromise. However, she warned that if Sleydo' violated the conditions of her release she may face a more stringent order in the future.
Multiple arrests
Sleydo' is one of the main spokespeople for the Gidim'ten clan of the Wet'suwet'en who on Nov. 14 issued notice they would be setting up a blockade to enforce the eviction of Coastal GasLink workers from its territory.
On Friday, Nov. 18, RCMP arrived in the region to take part in what they called a "rescue mission" of more than 500 workers who the company said were unable to get food, water or supplies because of the blockade.
After clearing the blockade, RCMP continued enforcement for a second day, which included the arrest of Sleydo' and fourteen others, including two journalists.
While some of those arrested Nov. 17 were released in Houston, the rest were transferred to Prince George where they were held over the weekend before two days of court hearings started Monday.
Conditions differ for Wet'suwet'en and non-Wet'suwet'en
The conditions for release varied depending on the identity of the person. While Wet'suwet'en members were told they could return to the exclusion zone to engage in cultural practices, non-Wet'suwet'en members are not allowed to return at all except in cases where they have to pick up belongings or travel home or — in the case of the journalists — for legitimate work purposes.
Shay Lynn Sampson, a member of the Gitxsan Nation who was released Monday, said the conditions for release were "racist." (Andrew Kurjata/CBC)
Among those not allowed to travel to the exclusion zone is a Mohawk man who was identified as being culturally Wet'suwet'en by virtue of being engaged to a member of the nation and been welcomed by chiefs.
Hereditary chief Woos of the Cas Yikh (Grizzly Bear House) of the Gidim'ten clan said the courts have no authority over who is and isn't a member of the Wet'suwet'en or who is allowed on their land.
"It's our land. It's Cas Yikh territory," he said. "It's a great insult."
Shay Lynn Sampson, a member of the neighbouring Gitxsan Nation who was released Monday called the conditions "racist".
"We go to our land for many different reasons," she said. "The court has no business deciding what is traditional cultural practices and what is not."
Speaking Tuesday evening after her release, Sleydo' said the courts have done an inadequate job of recognizing Indigenous sovereignty.
"This injunction doesn't take into account Wet'suwet'en law," she said. "I can't go freely on my territory ... we're going to challenge it to the full effect that we can."
Everyone released is expected back in court the week of Feb. 14 for the next portion of their hearings.
With files from Lenard Monkman
Pipeline dispute in B.C.: Journalists released, Leonardo DiCaprio shows support for First Nation
Two journalists have been been released three days after their arrest while covering an ongoing B.C. pipeline dispute that has drawn the attention of Hollywood actor Leonardo DiCaprio.
The journalists were arrested while covering the RCMP's enforcement of an injunction against protesters in northern B.C.
They were released by a B.C. Supreme Court judge Monday on the condition that they appear in court again in February. They must also comply with the same terms protesters are bound by, outlined in an injunction granted to Coastal GasLink by the same judge nearly two years ago.
Mounties said Friday that two people were arrested at the site for refusing to leave what they called in a statement "building-like structures," and that those people "later identified themselves as independent journalists."
Addressing the arrests in a statement Monday, B.C. RCMP Assistant Commissioner Eric Stubbs wrote that police understand the "important constitutional role" of the media, and that the RCMP's relationship with journalists is "based on mutual respect and professionalism."
He said that the two individuals who were arrested were not detained for performing their jobs, nor were they denied access to the area or told to stay in a specific place during enforcement efforts.
Stubbs said they were among a group of 11 who were told they were breaching the injunction, and did not identify themselves as journalists during a 60-minute period during which the injunction was read and protesters were given the opportunity to leave.
He said they only identified themselves when the arrests began, and that at that point they were held in custody until they could appear before a judge, as per the injunction order.
They were among 20 people who appeared before the Prince George court Monday.
Stubb said the RCMP's expectation is that members of the media identify themselves as soon as possible, and outlined the protocol in those cases, including that journalists' presence must not be interfering with those seeking to enforce the law, or take actions that could be considered aiding or abetting protesters.
B.C. Public Safety Minister Mike Farnworth said a free press is critical to democracy and he hoped the situation would not escalate.
The province has been doing “a significant amount of work over the last number of months to try and de-escalate tensions in the area,” he told a news conference.
The arrests were made in an area not far from a drilling site for an under-construction natural gas pipeline, and came at the same time as the arrests of several members of the Gidimt'en clan.
On Monday, actor DiCaprio shared a post from the clan on Twitter, expressing his support for pipeline opponents.
"After setting up a blockade to protect their land, community, and sacred headwaters Wedzin Kwa from Coastal GasLink’s planned fracked gas pipeline, the Wet’suwet’en Nation has faced militarized raids from the RCMP. We must protect the rights of land defenders," he wrote.
The clan is one of five in the Wet'suwet'en Nation. Members had set up blockades along a forest service road earlier this month. The road was cleared on Thursday, according to the RCMP.
Opposition among Wet'suwet'en hereditary chiefs to the 670-kilometre pipeline route sparked rallies and rail blockades across Canada early last year, while the elected council of the Wet'suwet'en First Nation and others in the area have agreed to the project.
With files from The Canadian Press
Photo posted by Gidimt'en Checkpoint on Facebook on Nov. 14, 2021.
GoFundMe to help beloved Canadian actor Scott Hylands
Author of the article:
Liz Braun
Publishing date:
Nov 22, 2021
Scott HylandsPHOTO BY GOFUNDME /TORONTO SUN
Article content
Well-known Canadian actor Scott Hylands could use your help.
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Hylands, 78 — perhaps best known for the hit detective TV series Night Heat — was diagnosed with Acute Myeloid Leukemia (AML) on Oct. 1
This is shattering news to his family. Only six weeks prior to diagnosis, Hylands was performing his self-written, sold-out, one-man Shakespeare play Lend Me Your Ears , on Salt Spring Island, BC.
And just a few weeks after that, he was celebrating his daughter’s wedding.
Intensive chemotherapy is required to fight AML, and it works best in conjunction with a drug called Venclexta.
Venclexta is approved in Canada but it costs between $60,000 and $80,000 for treatment. Studies from the U.S. show that Venclexta plus chemotherapy shows excellent results for remission. And the drug is targeted especially to the actors’ age group.
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A GoFundMe to raise the money for Venclexta has been organized by Hylands’ wife, Veronica Hylands.
The Scott Hylands Immunotherapy Fundraiser began with a modest appeal to the community on Salt Spring Island, where the Hylands lived for 25 years and raised their two children. That helped them raise just over half the $50,000 goal.
Word got out quickly in the industry, and many of Hylands’ old cast-mates, including Jeff Wincott and actor-director Clark Johnson, as well as other people on both sides of the camera, have contributed.
Former Night Heat co-star Wincott (currently starring in The Issue With Elvis ) spoke fondly of his work experience with Hylands, saying he’d been as much a teacher as a partner on the show.
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“I was lucky to have worked with him on my first big acting job. He taught me a lot. He was always prepared, professional and he cared deeply about doing good work, a lesson and example I carried with me throughout my career,” Wincott said.
In an interview on Monday, Veronica Hylands, the actor’s wife of 31 years, said the first shipment of Venclexta was on its way.
“They’re calling it a miracle drug,” she said. “With the combination of chemotherapy and Venclexta, the prognosis improves astronomically.”
She and their two adult children are still in shock over Hylands’ diagnosis. His wife said he has otherwise been the healthiest person she knows.
“This is overwhelming to us,” she said.
Despite the success Hylands had on TV a generation ago, he is, like so many Canadians, a journeyman actor.
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“There are no residuals,” said Veronica Hylands. “I’m sure people will wonder, ‘You don’t have the money?” and yes, his show was successful, but that was 30 years ago. He still works for a living at his age.
“We don’t live high off the hog,” she said.
She doesn’t sound embarrassed — she just wants people to know they wouldn’t ask if they didn’t need the help. It’s unfamiliar territory. The Hylands contribute regularly to Sick Kids Hospital, B.C. Kids and other good causes.
“We’ve never had to ask a penny from anyone before,” she said. “If the drug weren’t so promising, we wouldn’t be doing this.”
One thing the GoFundMe has shown her is that there’s a lot of love out there for her husband — in film, TV and theatre. All kinds of people in the entertainment industry have contributed to the GoFundMe, said Hyland.
“We are thriving on the kindness of people. There are people stepping up to help, some we haven’t spoken to in 30 years,” she said.
“The response from his old cast-mates has been wonderful. There were people who worked on that show who were kids back then. They never really spoke to him, but out of respect, they have contributed.
“It’s because he always treated everyone equally.”
Washington state cops use DNA to clear 1959 child murder, the 'Mount Everest of cold cases'
The killer's daughter volunteered to submit a DNA sample that revealed John Reigh Hoff was the probable murderer
Author of the article:Brad Hunter Publishing date:Nov 22, 2021 •
Candy Rogers, 9, disappeared in March 1959. Her remains were found two weeks later. She had been raped and strangled to death. Cops have finally named her killer.
PHOTO BY HANDOUT /SPOKANE POLICEW Article content
Homicide detectives in Washington state have closed the horrific 1959 murder of a nine-year-old girl who was selling mints.
With the help of the killer’s family.
Cops say they used DNA evidence to crack the 62-year-old cold case sex slaying of Candy Rogers in Spokane.
Candy disappeared on March 6, 1959 and her body was discovered two weeks later, raped and strangled with her own clothes. She had been selling Camp Fire Girl mints.
Now, detectives say her killer was U.S. Army deserter John Reigh Hoff. Hoff took his own life in 1970.
Det. Zac Storment told reporters that a long nightmare has finally come to a conclusion in the Pacific Northwest city.
The killer is US Army deserter John Reigh Hoff. Hoff committed suicide in 1970.
HANDOUT/ SPOKANE POLICE
“It’s the Mount Everest of our cold cases, the one we could never seem to overcome, but at the same time nobody ever forgot,” he said, adding that the DNA evidence recently linked Hoff to the murder.
His sister had been a friend of Candy’s.
The victim’s surviving relatives cried tears of joy after learning who murdered the “cute” little girl.
“I feel like Candy’s loss was just a horrible loss. She was just so cute,” cousin Joanne Poss said.
Storment said detectives conducted a DNA test on a well-preserved semen sample found on Candy’s clothes. It linked to three brothers, John Reigh, Andrew and Terry Allen Hoff.
The killer’s daughter volunteered to submit a DNA sample that revealed John Reigh Hoff was the probable killer. His sister, who was 10 at the time, was Candy’s “big sister” in the Camp Fire Girls.
“It takes a while for it to sink it,” said Hoff’s daughter Cathie, who was nine when he killed himself. “It’s just sad when you find out … that someone in your family could do something like that.”
Candy Rogers, 9, disappeared in March 1959. Her remains were found two weeks later. She had been raped and strangled to death. Cops have finally named her killer.
HANDOUT/ SPOKANE POLICE
Hoff would attack another woman in similar fashion in 1961 and was jailed for six months. A brief foray into the military ended with desertion.
He was 31 when he killed himself.
“I thank God that I lived long enough to see the end of this case,” retired Spokane Police Capt. Richard Olberding said. He was one of the cops who found the girl’s tiny body.
Candy was an only child and both her parents are now dead.
Curious Kids: Why are there so few impact craters on Earth?
The Conversation 23 Nov 2021
Curious Kids is a series for children in which we ask experts to answer questions from kids.
Why are there so few craters on Earth? (Ivon, 11, Butterworth, South Africa)
Thank you for the great question, Ivon. Scientists call these "impact craters": a bowl-shaped depression in the rocky crust of a planet, moon or asteroid that is caused by another rocky piece of rocky space debris slamming into it really fast. This high-speed collision - over 36000 kilometres per hour! - releases a huge amount of energy that causes a lot of destruction.
I am a geoscientist who studies impact sites in Africa and on other continents. Scientists like me have identified the remains of around 200 impact craters across our planet. Some people might think that 200 is quite a big number, but you are right - compared to the Moon and the other rocky planets and moons in our solar system, it is exceptionally low. There are several reasons for this.
Understanding Earth
The first reason is that Earth's surface is continuously changing because we live on a geologically active planet. Impact craters are relatively shallow, so these "dents" in Earth's rocky crust (the surface bit we can see with our eyes) can be easily buried or wiped out by erosion. For instance, the giant, 160-km-wide Chicxulub crater in Mexico that wiped out most of the dinosaurs and many other species 65 million years ago is only 1-2 km deep and is hidden beneath younger layers of sediment. In contrast, the much older, equally famous, Vredefort crater in South Africa has experienced millions of years of erosion by rivers or glaciers so that the crater itself has been erased. Fortunately, ring-shaped patterns in the rocks indicate that something very violent and unusual happened in the distant past.
The next reason is that two-thirds of Earth's rocky crust is hidden beneath the oceans. We actually know less about many parts of the deep ocean floor than the surfaces of other planets in the solar system. Could there be lots of craters hidden beneath the oceans? We don't know the answer for sure, but probably not, because there is something unusual about Earth's oceanic crust: it is much, much younger than the continental crust on which we live and the crusts of the Moon and other planets.
Let me explain. Since the 1960s we have known that new ocean crust is being created almost continuously along giant rifts (called mid-ocean ridges). At the same time, other parts of this basalt crust are sinking back into the mantle along subduction zones. This is like a conveyor belt and is part of what we call plate tectonics. The key point is that we can't find any oceanic crust that is older than 200 million years. This means that any crater that formed more than 200 million years ago in an ocean has been destroyed. That sounds like a long time, right? But it's a very small time window compared with the 4.6 billion years that Earth and the other planets have existed.
The presence of so much deep water on Earth means many smaller asteroids that would definitely make impact craters on dry land do not produce craters in the oceanic crust. This is because the water column absorbs all or most of the impact energy, maybe creating a short-lived tsunami but leaving no other trace.
Earth's atmosphere also plays a role in reducing the number of impact craters. One of the remarkable observations from the Apollo programme that studied the moon was that every single sample showed signs of high-speed impacts, down to micro-craters. Up until the 1970s many scientists thought the reason there were so few craters on Earth compared to the Moon was because our atmosphere caused the small asteroid debris to burn up (as meteors) and slow down as it passed through the atmosphere so that it didn't have enough energy left to blast a crater in the crust.
In some cases the atmosphere even "bounced" asteroids back into outer space, much like you can skip a stone across a pool of water. As there will be many more smaller craters - because there are many smaller asteroids - we can see that the atmosphere acts as both a filter and a shield to reduce the number of impacts.
Finally, we need to consider our own role in your question: how good are scientists and ordinary people at recognising impact craters? There are thousands of craters on Earth, but craters can also be formed in other ways, such as volcanic eruptions and sinkholes.
So, geoscientists need to carefully collect and examine all the evidence before they can confirm that a crater (or, rather, what's left of it) was formed by impact. Impact crater studies didn't really exist until about 60 years ago. Up until then, most of the craters on Earth were thought to be caused by volcanic eruptions.
Then scientists working on underground military nuclear explosions started looking into the physics of shock waves in rocks caused by the nuclear explosions. Others began scrutinising the thousands of craters on the Moon as preparation for the Apollo moon landings. When they went looking for similar craters on Earth, they started to find unusual evidence that the rocks in and around some craters had been affected by exceptional shock pressures and temperatures that could not be explained by volcanic eruptions.
So geoscientists have to be a bit like detectives: we need to collect evidence to prove that a crater was caused by an impact rather than by anything else. Every few years another crater is added to the list as the proof is presented to, and accepted by, the international geoscientific community.
There are many hundreds of possible, or suspected, impact craters on Earth that await confirmation or rejection, including dozens right here on the African continent where we live. Even though it's really big, Africa still has only 20 confirmed impact sites and is definitely underrepresented in the global list. This may be partly because of its geology but it is also because too few African geoscientists are looking for impact craters in Africa - maybe one day you can join us, Ivon, and help in the search!
Author: Roger Lawrence Gibson - Professor of Structural Geology and Metamorphic Petrology, University of the Witwatersrand
