This image shows magnetic anomalies in the South Pacific — underwater lines where the crust of the Earth either matches up with the planet's overall magnetic polarity (reds and purples) or is completely reversed (blues). Invisible to the naked eye, these stripes run along all of Earth's ocean basins. We first noticed them in the 1950s and, at first, they were a giant mystery. Why would there be these distinct lines of magnetism, and why would the lines fluctuate in their polarity? As Chris Rowan explains at the Highly Allochthonous blog, the answer ended up being a key part of proving that chunks of the Earth's crust were moving away from each other.
Fred Vine and Drummond Matthews thought through the consequences of the hypothesis put forward by Harry Hess, that new oceanic crust was being continuously produced by the eruption of basalt at mid-ocean ridges. When combined with the facts that newly cooled basalt has a strong remanent magnetisation aligned with the ambient magnetic field, and that the Earth’s magnetic field reverses its polarity every million years or so. Vine and Matthews* argued that if seafloor spreading was indeed occurring at mid-ocean ridges, then linear positive and negative magnetic anomalies, formed from crust produced in normal and reversed polarity chrons, would form a symmetric pattern around the mid-ocean ridges, which is exactly what we see.
Watch the skies! The peak of the Perseid meteor shower takes place overnight tonight! The bright quarter Moon will limit the number of shooting stars you’ll see but you can still expect around 15-20 per hour depending on where you’re at. The meteors are debris from Comet Swift-Tuttle burning up in Earth’s atmosphere at speeds […]
“The U.S. has reached a landmark of sorts in its so far not very successful battle with the virus that causes Covid-19 — most Americans now know someone who has been infected,” writes Justin Fox at Bloomberg, about coronavirus social data from Navigator Research, shown above.
Researchers successfully revived ancient microbes, some more than 100 million years old, that were buried in the seafloor. During an expedition to the South Pacific Gyre, the scientists from the Japan Agency for Marine-Earth Science and Technology (JAMSTEC) and their colleagues drilled into the ocean sediment almost 6,000 meters below the surface. “Our main question […]
If you want swole arms cut like tree trunks, you start savaging the curl bars. If you want to sculpt a tight, firm core, you have lots of planking and bridges in your future. So what do you do if you want to knock out that double chin? Or put a little added definition into […]
Considering the state of our world, it probably shouldn’t come as a surprise to find lots and lots of people pushed to their breaking point. Anxiety and stress are often constant companions during the best of times. But now, with fear and frustration running rampant, it’s easy to be subsumed by all the distractions and […]
Most of us aren’t constantly beset by poor posture. But all it takes is some subtle misalignment while you’re doing serious hours behind the wheel driving or working away at a desk to do a real number on your back. In fact, most of us are so unaware of the mechanics of good posture that […]