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Japan Today
27-06-2025
- Science
- Japan Today
Canadian rocks may be the oldest on Earth
This photo provided by researcher Jonathan O'Neil shows an outcropping of about 4.16 billion year old rocks at the Nuvvuagittuq Greenstone Belt in northeastern Canada, with a knife to indicate scale. By ADITHI RAMAKRISHNAN Scientists have identified what could be the oldest rocks on Earth from a rock formation in Canada. The Nuvvuagittuq Greenstone Belt has long been known for its ancient rocks — plains of streaked gray stone on the eastern shore of Hudson Bay in Quebec. But researchers disagree on exactly how old they are. Work from two decades ago suggested the rocks could be 4.3 billion years old, placing them in the earliest period of Earth's history. But other scientists using a different dating method contested the finding, arguing that long-ago contaminants were skewing the rocks' age and that they were actually slightly younger at 3.8 billion years old. In the new study, researchers sampled a different section of rock from the belt and estimated its age using the previous two dating techniques — measuring how one radioactive element decays into another over time. The result: The rocks were about 4.16 billion years old. The different methods "gave exactly the same age,' said study author Jonathan O'Neil with the University of Ottawa. The new research was published Thursday in the journal Science. Earth formed about 4.5 billion years ago from a collapsing cloud of dust and gas soon after the solar system existed. Primordial rocks often get melted and recycled by Earth's moving tectonic plates, making them extremely rare on the surface today. Scientists have uncovered 4 billion-year-old rocks from another formation in Canada called the Acasta Gneiss Complex, but the Nuvvuagittuq rocks could be even older. Studying rocks from Earth's earliest history could give a glimpse into how the planet may have looked — how its roiling magma oceans gave way to tectonic plates — and even how life got started. 'To have a sample of what was going on on Earth way back then is really valuable,' said Mark Reagan with the University of Iowa, who studies volcanic rocks and lava and was not involved with the new study. The rock formation is on tribal Inukjuak lands and the local Inuit community has temporarily restricted scientists from taking samples from the site due to damage from previous visits. After some geologists visited the site, large chunks of rock were missing and the community noticed pieces for sale online, said Tommy Palliser, who manages the land with the Pituvik Landholding Corp. The Inuit community wants to work with scientists to set up a provincial park that would protect the land while allowing researchers to study it. 'There's a lot of interest for these rocks, which we understand,' said Palliser, a member of the community. 'We just don't want any more damage.' © Copyright 2025 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed without permission.
Japan Today
26-05-2025
- Health
- Japan Today
You should wear sunscreen even if you have darker skin. Here's why
By ADITHI RAMAKRISHNAN People with darker skin still need to wear sunscreen — for more reasons than one. Too much ultraviolet exposure from the sun can lead to sunburn, dark spots and wrinkles, and increased risk of skin cancer. The melanin in darker skin offers some extra protection from the sun, but dermatologists say that isn't enough on its own. "Everyone needs sunscreen. But the reasons that one might be reaching for sunscreen may differ depending on your skin tone,' said Dr. Jenna Lester, who founded the Skin of Color Clinic at the University of California, San Francisco. White people are overall more likely to get skin cancer compared to Black and Hispanic people. But Black and Hispanic people are less likely to survive the most dangerous kind of skin cancer called melanoma, according to the American Cancer Society. Black patients more commonly get melanoma on their hands and feet — places that are more shielded from the sun. Still, sunscreen is an additional protective layer that helps prevent a host of other problems including sunburns, hyperpigmentation after acne, rosacea and dark patches on the face. Dr. Oyetewa Asempa at Baylor College of Medicine often reminds her darker-skinned patients: 'All of the problems that you're coming to see me for are caused or worsened by the sun.' To stay safe in the sun, it's important to grab sunscreen with a sun protection factor or SPF of at least 30 and reapply every two hours. People headed for the pool or beach should put on sunscreen beforehand, remembering to reapply liberally and after getting out of the water. Most people don't wear enough sunscreen when they apply, Lester said. Make sure to put two long fingers' worth on the face and a hefty blob for the body. Look for chemical-based sunscreens to avoid ashy white cast. Two key ingredients in mineral-based products — zinc oxide and titanium oxide — are the culprits for that pesky discoloration on dark skin. Tinted sunscreens contain pigments that block visible light from the sun, offering additional protection against dark spots. And wearing a hat or sun-protective clothing with an ultraviolet protection factor or UPF grading can provide an extra safety boost. Whatever the sun protection routine, it's important to keep it up, Lester said. Some UV rays can climb right through car and house windows to cause sun damage even when indoors, making it even more important to take care of the skin while the sun shines. 'It's about trying to make it a daily habit,' she said. 'Consistency over intensity.' The Associated Press Health and Science Department receives support from the Howard Hughes Medical Institute's Science and Educational Media Group and the Robert Wood Johnson Foundation. The AP is solely responsible for all content. © Copyright 2025 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed without permission.
