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A newly discovered crater suggests a second impact that would have triggered underwater landslides and tsunamis On its own, the dinosaur-killing asteroid had a staggering impact: Wildfires raged across the continents, tsunamis pummeled coastlines and about three-quarters of Earth’s species went extinct. But now, new evidence suggests this massive chunk of rock may have had a partner: Scientists discovered what might be an impact crater off the coast of Guinea that they say dates to 66 million years ago—around the same time as the collision that wiped out the dinosaurs. This second asteroid may have broken off from the dinosaur-killer, known as Chicxulub, or it may have been part of a closely timed impact cluster, according to a new study published in Science Advances. “A lot of people have questioned: How could the Chicxulub impact—albeit a huge one—be so globally destructive?” Veronica Bray, a planetary scientist from the University of Arizona and paper co-author, tells National Geographic’s Maya Wei-Haas. “It might be that it had help.” Researchers discovered what they dubbed the Nadir crater—named after a nearby underwater volcano—in 2020, while examining seismic survey data. “We came across a highly unusual feature,” write Bray and co-authors Uisdean Nicholson and Sean Gulick for The Conversation. “Among the flat, layered sediments of the Guinea Plateau, west of Africa, was what appeared to be a large crater, a little under 10 km wide and several hundred meters deep, buried below several hundred meters of sediment.” Nicholson, a geoscientist from Heriot-Watt University in the United Kingdom, has been interpreting such surveys for about 20 years. But he has “never seen anything like this,” he tells BBC News’ Jonathan Amos. Though scientists haven’t confirmed it was caused by an asteroid, features of Nadir, including its scale, the ratio of height to width and the height of the crater rim, are consistent with an impact origin, write the authors in The Conversation. Additionally, deposits around Nadir look like materials ejected from a crater after a collision. Computer modeling showed that to cause this impact, an asteroid would likely have been about 0.25 miles across and hit an ocean that was more than 2,600 feet deep, per The Conversation. In comparison, the Chicxulub asteroid was likely around six miles wide. Still, this second impact would have been sizable. “The energy released would have been around 1,000 times greater than that from the January 2022 eruption and tsunami in Tonga,” Bray tells BBC News. The hit would have caused shock waves equivalent to a magnitude 6.5 or 7 earthquake, which would have triggered underwater landslides and a series of tsunamis, write the authors. “The discovery of a terrestrial impact crater is always significant, because they are very rare in the geologic record,” Mark Boslough, an earth and planetary scientist at the University of New Mexico, who was not involved in the research, tells CNN’s Katie Hunt. “There are fewer than 200 confirmed impact structures on Earth and quite a few likely candidates that haven’t yet been unequivocally confirmed.” To verify that Nadir was truly formed by an asteroid strike, as well as find a precise date for the collision and determine its connection to Chicxulub, scientists will need to drill into the formation and collect samples. The team has already applied for emergency funds for this additional research, per National Geographic. The drilling could also give scientists clues about how life on Earth responded to the impact. “Part of the Nadir drilling goal is to analyze the sediment that was deposited onto Nadir over time,” Bray tells Inverse’s Kiona Smith. “When did life recover? How?” Smithsonian Magazine article by Margaret Osborne

During the last ice age, humans ventured into two vast and completely unknown continents: North and South America. For nearly a century, researchers thought they knew how this wild journey occurred: The first people to cross the Bering Land Bridge, a massive swath of land that connected Asia with North America when sea levels were lower, were the Clovis, who made the journey shortly before 13,000 years ago. According to the Clovis First theory, every Indigenous person in the Americas could be traced to this single, inland migration, said Loren Davis, a professor of anthropology at Oregon State University. But in recent decades, several discoveries have revealed that humans first reached the so-called New World thousands of years before we initially thought and probably didn’t get there by an inland route. So who were the first Americans, and how and when did they arrive? Genetic studies suggest that the first people to arrive in the Americas descend from an ancestral group of Ancient North Siberians and East Asians that mingled around 20,000 to 23,000 years ago and crossed the Bering Land Bridge sometime between then and 15,500 years ago. Geneticists studying the first Americans tend to paint a more consistent picture than archaeologists do, mainly because they’re using the same human remains and genetic datasets. Genetic analyses have found that Ancient North Siberians and a group of East Asians paired up around 20,000 to 23,000 years ago. Soon after, the population split into two genetically distinct groups: one that stayed in Siberia, and another, the basal American branch, which emerged around 20,000 to 21,000 years ago. Genetic data suggest the descendants of this basal American branch crossed the Bering Land Bridge and became the first Americans. But some archaeological sites hint that people may have reached the Americas far earlier than that. There are fossilized human footprints in White Sands National Park in New Mexico that may date to 21,000 to 23,000 years ago. That would mean humans arrived in North America during the Last Glacial Maximum (LGM), which occurred between about 26,500 to 19,000 years ago, when ice sheets covered much of what is now Alaska, Canada and the northern U.S. Other, more equivocal data suggest the first people arrived in the Western Hemisphere by 25,000 or even 31,500, years ago. If these dates can be confirmed, they would paint a much more complex picture of how and when humans reached the Americas. Almost all scientists agree, however, that this incredible journey was made possible by the emergence of Beringia — a now-submerged, 1,100-mile-wide (1,800 kilometers) landmass that connected what is now Alaska and the Russian Far East. During the last ice age, much of Earth’s water was frozen in ice sheets, causing ocean levels to fall. Beringia surfaced once waters in the North Pacific dropped roughly 164 feet (50 meters) below today’s levels; it was passable by foot between 30,000 and 12,000 years ago. From there, the archaeological picture gets muddier. The older version of the story originated in the 1920s and 1930s, when Western archaeologists discovered sharp-edged, leaf-shaped stone spear points near Clovis, New Mexico. The people who made them, now dubbed the Clovis people, lived in North America between 13,000 and 12,700 years ago, based on a 2020 analysis of bone, charcoal and plant remains found at Clovis sites. At the time, it was thought that the Clovis traveled across Beringia and then moved through an ice-free corridor, or “a gap between the continental ice sheets,” in what is now part of Alaska and Canada. However, new discoveries have turned back the clock on the first Americans’ arrival. In 1976, researchers learned about the site of Monte Verde II in southern Chile, which radiocarbon dating showed was about 14,550 years old. It took decades for archaeologists to accept the dating of Monte Verde, but soon, other sites also pushed back the date of humans’ arrival in the Americas. The Paisley Caves in Oregon contain human coprolites, or fossilized poop, dating to about 14,500 years ago. Page-Ladson, a pre-Clovis site in Florida with stone tools and mastodon bones, dates to about 14,550 years ago. And Cooper’s Ferry — a site that includes stone tools, animal bones and charcoal — dates to around 16,000 years ago. Then, in 2021, scientists announced much more ancient traces of human occupation: fossilized footprints in White Sands, New Mexico dating to between 21,000 and 23,000 years ago. Sites such as White Sands and Cooper’s Ferry have big implications for how the first people arrived in the Americas. It’s thought that the ice-free corridor through North America didn’t fully open until about 13,800 years ago. So if humans were in the Americas long before then, they likely traveled there along the Pacific coast. That coastal journey could have been made by foot, by watercraft, or both. But no fossil or archaeological evidence of this journey has been unearthed. Ideally, archaeologists would like to find more sites from all of these branches, especially any remains that could explain the genetics behind the people at White Sands between 23,000 and 21,000 years ago. Evidence of these long-lost people can be found in the remains of the animals they butchered, the charcoal they burned, the tools they crafted and the loved ones they buried. Local Indigenous Peoples’ stories strongly suggest humans were in the area during the Ice Age Floods, but tangible scientific evidence is sparse and yet to be found in the area. Eedited from a Live Science article by Laura Geggel

Some 240 million years ago, an enormous supercontinent known as Pangea encompassed nearly all of Earth’s extant land mass, Pangea bore little resemblance to our contemporary planet, but thanks to a recently released interactive map interested parties can now superimpose the political boundaries of today onto the geographic formations of yesteryear—at least dating back to 750 million years ago. Ancient Earth is an interactive Map tool that enables users to home in on a specific location and visualize how it has evolved between the Cryogenian Period and the present. The tool behind this millennia-spanning visualization, is the brainchild of Ian Webster, curator of the world’s largest digital dinosaur database. Webster drew on data from the PALEOMAP Project—spearheaded by paleogeographer Christopher Scotese, the initiative tracks the evolving “distribution of land and sea” over the past 1,100 million years—to build the map. Users can input a specific address or more generalized region, such as a state or country, and then choose a date ranging from zero to 750 million years ago. Currently, the map offers 26 timeline options, traveling back from the present to the Cryogenian Period at intervals of 15 to 150 million years. Ancient Earth includes an array of helpful navigational features, including toggle display options related to globe rotation, lighting and cloud coverage. Brief descriptions of chosen time periods pop up on the bottom left side of the screen, while a dropdown menu at the top right allows users to jump to specific milestones in history, from the arrival of Earth’s first multicellular organisms some 600 million years ago to early hominids’ relatively belated emergence around 20 million years ago. To switch from one time period to another, you can either manually choose from a dropdown menu or use your keyboard’s left and right arrow keys. Start at the very beginning of the map’s timeline and you’ll see the planet evolve from “unrecognizable blobs of land” to the massive supercontinent of Pangea and, finally, the seven continents we inhabit today. Edited from Smithsonian Magazine article by Meilan Solly, February 15, 2019

The rapid decline of the British-Irish Ice Sheet thousands of years ago may hold lessons for how melting ice sheets in Greenland and Antarctica will influence sea-level rise in the future. In an animation that spans tens of thousands of years, an ancient ice sheet grows to envelope land masses that would one day be known as Great Britain and Ireland. After thousands of years elapse, the ice then retreats to expose the land once more. Known as the British-Irish ice sheet, the frozen mass began its relentless march about 33,000 years ago. Around 10,000 years later, the land was covered in ice half a mile thick. But just 5,000 years after that, the glacier had melted away, vanishing in a mere blink of geological time. Human populations that had fled a millennia-long winter returned to settle the thawing land just as the last ice age drew to a close. Representing years of research, this animation highlights how quickly the British-Irish Ice Sheet declined. And the data driving the animation may help scientists to better understand how modern ice loss due to climate change contributes to sea-level rise.Scottish geologist Archibald Geikie first mapped the British-Irish Ice Sheet’s shape in 1894 and, over the past century, scientists have slowly carved out details of its formation and decline, publishing their findings in more than 1,000 scientific publications, according to the website of BRITICE-CHRONO(opens in new tab) a five-year, $4.2 million endeavor to map the British-Irish Ice Sheet. Ultimately it was the specter of human-caused climate change that drove one team of BRITICE-CHRONO researchers to bring together existing data and collect more; they published their findings Sept. 7 in the journal Boreas(opens in new tab). In creating the new animation, the scientists visualized the most complete picture to date of the ancient ice sheet’s rise and fall. The BRITICE-CHRONO team scoured prior studies and compiled data on more than 20,000 landforms that currently exist along the path of the ice sheet — from hill-like drumlins, or small ridges, to masses of soil and rock left behind by the moving glacier. The scientists then visited locations on land and sea, collecting data from 914 sites — some of which were only accessible via submarine, they reported in the study. They calculated the geometric contours of the ice sheet from features in the terrain, estimating the timing of the glacier’s retreat from carbon-dated sediment, including animal remains. Their efforts produced three times more data than any prior simulation of the British-Irish ice sheet; the team then fed the data into a computer model that assessed how the ice would have interacted with its environment over tens of thousands of years. Their animation presented the resulting maps as a time-lapse of the glacier’s expansion and eventual demise. Although this particular ice sheet melted thousands of years ago, the details of its growth and collapse may hold lessons for climate scientists studying the alarming decline of two modern ice sheets: one in Antarctica and the other in Greenland. Since 1901, these two ice sheets have lost 49,000 gigatonnes of ice — enough to coat the United States in 22 feet (6.7 meters) of ice, or enough to cover the entire surface of the moon in an ice sheet five feet (1.5 m) tall, according to NASA(opens in new tab). That melted ice ended up in the ocean, where it has been the single largest contributor to sea-level rise in the past few decades, according to the United Nations’ International Panel on Climate Change(opens in new tab). Even if humans were to cut all fossil fuel emissions tomorrow, a 2022 study in Nature Climate Change(opens in new tab) suggests that ice lost from the Greenland ice sheet would still cause a 10-inch (25-centimeter) sea level rise. Rising sea levels, in turn, will likely mean more punishing storms with worse flooding; the disruption of fragile ecosystems; and the mass displacement of millions of people who live along the coast. Projects such as BRITICE-CHRONO, which look back at the lifespans of long-gone ice sheets, may help scientists predict the decline of modern ice sheets and plan for the future, the researchers reported. Article by Joshua A. Krisch, taken from Live Science  

Indigenous people have been in the Americas longer than archaeologists once thought. Stone tools unearthed from a rock shelter in Southern Oregon were last used more than 18,000 years ago, radiocarbon dating suggests. That makes the site one of the oldest-known human living spaces in the Americas. Buried deep beneath a layer of volcanic ash, archaeologists excavating Rimrock Draw Rockshelter found two stone scraping tools, which ancient knappers had skillfully shaped from pieces of orange agate. A residue of dried bison blood still clung to the edges of one scraper, a remnant of the last bit of work some ancient person had done with the tool before discarding it. The layer of volcanic ash above the tools had blasted out of Mount St. Helens, a few hundred kilometers north of the rock shelter, 15,000 years ago, long after the fine agate scrapers, and the people who made and used them, had been forgotten. In a layer of dirt below the volcanic ash but above the stone tools, archaeologists found broken teeth from now-extinct relatives of modern camels and bison. Radiocarbon dating on a piece of bison tooth enamel (first in 2012, and confirmed recently by more testing) suggests the teeth belonged to animals that lived about 18,250 years ago. And because those teeth were buried in a layer of dirt above the stone tools, they must have ended up in Rimrock Draw sometime after the tools. That makes the agate scraper, complete with bloody evidence of its use, more than 18,000 years old—and one of the oldest traces of human presence in North America. But the people who lived in Oregon more than 18,000 years ago almost certainly weren’t the first to call the continent home. In Idaho, the Nimiipuu (Nez Perce) know the Cooper’s Ferry archaeological site as the ancient location of a village they call Nipehe. The oldest artifacts unearthed at the site date to at least 16,000 years ago, and it looks like people lived there, at least off and on, for several thousand years after those first arrivals. To have reached Cooper’s Ferry 16,000 years ago, the ancient inhabitants of Nipehe would have had to cross Beringia, a land mass that connected what’s now Russia with what’s now Canada during the last Ice Age, when sea levels were lower. They then had to move south along the Pacific Coast of North America, skirting along the western edge of the great ice sheet, until they reached the southern edge of the ice. The ice-free corridor wouldn’t open until about 15,000 to 14,000 years ago. By then, people were already living far, far south of the ice: Archaeologists found stone tools and butchered mastodon bones submerged in a Florida sinkhole that dated back to 14,500 years ago. And in Chile, someone left behind a single footprint 14,600 years ago. Thanks to footprints on an island off the coast of what’s now British Columbia, we know that at least some people did make their way along the coasts about 13,000 years ago. But some archaeologists, like Bournemouth University’s Matthew Bennett and his colleagues, say that those coastal migrants may have found their way into a continent already home to people who arrived at least 26,000 years ago—long before the ice sheets blocked the way into North America from Asia. In the mountains of north-central Mexico, archaeologists unearthed stone tools from Chiquihuite Cave, which dated back to around 30,000 years ago. And at White Sands National Monument in New Mexico, it appears that someone walked along the ancient shoreline of Lake Otero (now long since dry) between 23,000 and 21,000 years ago, leaving behind a trail of 61 footprints. Archaeologists dated the White Sands footprints thanks to grass seeds trapped in the layers of clay and silt above and below the tracks, which helped bracket their possible age. Some archaeologists are still skeptical, partly because there are so few sites this old south of the ice sheets, but there’s enough evidence to take the claims seriously. Taken from an article by KIONA N. SMITH published in arsTechnica