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Ice Ages Blamed on Tilted Earth By Michael Schirber LiveScience Staff Writer posted: 30 March 2005 In the past million years, the Earth experienced a major ice age about every 100,000 years. Scientists have several theories to explain this glacial cycle, but new research suggests the primary driving force is all in how the planet leans. The Earth’s rotation axis is not perpendicular to the plane in which it orbits the Sun. It's offset by 23.5 degrees. This tilt, or obliquity, explains why we have seasons and why places above the Arctic Circle have 24-hour darkness in winter and constant...

Like any spinning object, Earth is subject to centrifugal force, which tugs on the planet's fluid interior. At the equator, where this force is strongest, Earth is more than 26 miles larger in diameter than at the poles. Gordon said true polar wander may occur when dense, highly viscous bumps of mantle build up at latitudes away from the equator. If the mantle anomalies are massive enough, they can unbalance the planet, and the equator will gradually shift to bring the excess mass closer to the equator. The planet still spins once every 24 hours and true polar wander does...

As Earth's tectonic plates dive beneath one another, they drag three times as much water into the planet's interior as previously thought. Those are the results of a new paper published today (Nov. 14) in the journal Nature. Using the natural seismic rumblings of the earthquake-prone subduction zone at the Marianas trench, where the Pacific plate is sliding beneath the Philippine plate, researchers were able to estimate how much water gets incorporated into the rocks that dive deep below the surface. The find has major ramifications for understanding Earth's deep water cycle, wrote  marine geology and geophysics researcher Donna Shillington...

A new study says we may only have another 1.45 billion years to enjoy the dynamic action of Earth’s geologic engine There’s no geological artist quite like Earth’s plate tectonics. Thanks to this ongoing operation, we have mountains and oceans, terrifying earthquakes, incandescent volcanic eruptions, and new land being born every single second. But nothing lasts forever. Eventually, the mantle will cool to such an extent that this planetwide conveyor belt will grind to a halt. At that point, you can say farewell to the carbon cycle, as well as the constant reshaping and reshuffling of landmasses that have been...

In the early Cretaceous period, between 125 and 120 million years ago, researchers discovered that dinosaurs began moving away from Europe. A team of scientists from the University of Leeds created a computer model of the fossil record of dinosaurs to figure out their migration pattern up until their extinction 65 million years ago. They found that there was a mass exodus of dinosaurs between 125 and 120m years ago while no new species were moving in. Lead author of the study published in the Journal of Biogeography, Dr Alex Dunhill, of Leeds University, said: "This is a curious result...

An international study led by researchers at Macquarie University has uncovered the ways in which giant meteorite impacts may have helped to kick-start our planet's global tectonic processes and magnetic field. The study, being published in the premier journal Nature Geoscience, explores the effect of meteorite bombardment, in geodynamic simulations of the early Earth. Our results indicate that giant meteorite impacts in the past could have triggered events where the solid outer section of the Earth sinks into the deeper mantle at ocean trenches – a process known as subduction. This would have effectively recycled large portions of the Earth's...

A piece of Canada that broke off about 1.7 billion years ago has been found in Australia. Geologists analyzed chemical signatures for very ancient sedimentary rocks in Georgetown, Queensland, that offer clues about where those rocks were when they formed. At that time, the continents were drifting together to form a supercontinent called Nuna or Columbia. The data suggests that the Georgetown rocks broke off from Canada and collided with northern Australia around 1.6 billion years ago. It remained there even after Nuna broke apart 300 million years later. The researchers found a geological signature that "cannot be linked with...

Geologists matching rocks from opposite sides of the globe have found that part of Australia was once attached to North America 1.7 billion years ago. Researchers from Curtin University in Australia examinedrocks from the Georgetown region of northern Queensland. The rocks — sandstone sedimentary rocks that formed in a shallow sea — had signatures that were unknownin Australia but strongly resembled rocks that can be seen in present-day Canada. The researchers, who described their findings online Jan. 17 in the journal Geology, concluded that the Georgetown area broke away from North America 1.7 billion years ago. Then, 100 million years...

The physical mechanism causing the unique, sharp bend in the Hawaiian-Emperor seamount chain has been uncovered in a collaboration between the University of Sydney and the California Institute of Technology (Caltech). Led by a PhD candidate at the University of Sydney's School of Geosciences, researchers used the Southern Hemisphere's most highly integrated supercomputer to reveal flow patterns deep in the Earth's mantle -- just above the core -- over the past 100 million years. The flow patterns explain how the enigmatic bend in the Hawaiian-Emperor seamount chain arose. True to the old adage -- as above, so below -- the...

The southeastern United States has been hit by a series of strange unexplained quakes - most recently, the 2011 magnitude-5.8 earthquake near Mineral, Virginia that shook the nation's capital. Researchers have been baffled, believing the areas should be relatively quiet in terms of seismic activity, as it is located in the interior of the North American Plate, far away from plate boundaries where earthquakes usually occur. Now, they believe the quakes could be caused by pieces of the Earth's mantle breaking off and sinking into the planet.

For hundreds of millions of years, Earth's climate has remained on a fairly even keel, with some dramatic exceptions: Around 80 million years ago, the planet's temperature plummeted, along with carbon dioxide levels in the atmosphere. The Earth eventually recovered, only to swing back into the present-day ice age 50 million years ago. Now geologists at MIT have identified the likely cause of both ice ages, as well as a natural mechanism for carbon sequestration. Just prior to both periods, massive tectonic collisions took place near the Earth's equator -- a tropical zone where rocks undergo heavy weathering due to...

Fun fact for you: scientists don't really know how the Himalayas formed. I mean yeah, they realize that the India tectonic plate is slamming into the Eurasia plate and has been for about 50 million years, but the mystery is why the mountain range is still growing. Usually when two continents collide it's like a car wreck -- there may be a bunch of mangled crust in the middle (mountains), but both vehicles stop moving. Turns out, India appears to be sinking into the mantle. A new study based on computer models of the two plates shows that the formation...

First… it’s important to understand that this is the most profound disagreement in all of science in a century and a half… and, even so, it is the tip of the iceberg, the ramifications of this disagreement will change everything we know in science, top to bottom. To begin with basic stuff. All science knows… The earth has two crusts. One…the mostly basalt lower crust or the oceanic crust which is 2 – 4 miles deeper down than the higher upper continental crust. This lower crust, essentially covers the Earth. It … this crust is being made daily at rift...

The first global map of magnetic peculiarities - or anomalies - on Earth has been assembled by an international team of researchers. Magnetic anomalies are caused by differences in the magnetisation of the rocks in the Earth's crust. Many years of negotiation were required to obtain confidential data from governments and institutes. Scientists hope to use the map to learn more about the geological composition of our planet. The World Digital Magnetic Anomaly Map (WDMAM) is available through the Commission for the Geological Map of the World. The magnetic signature of the Earth's crust has been measured for many decades...

No boats required. In the distant future, most if not all of today's continents (brown fragments, depicted with current-day outlines) will assemble into a single landmass called Amasia (shown approximately 100 million years from now). Over the next few hundred million years, the Arctic Ocean and the Caribbean Sea will disappear, and Asia will crash into the Americas forming a supercontinent that will stretch across much of the Northern Hemisphere. That's the conclusion of a new analysis of the movements of these giant landmasses. Unlike in today's world, where a variety of tectonic plates move across Earth's surface carrying the...

Geoscientists in Scotland say they have evidence to disprove the controversial "Snowball Earth" theory - the idea that the planet was completely encased in ice just over 600 million years ago.We are claiming that in reality there was not a totally frozen snowball Earth and that even during the coldest conditions large regions remained ice-free -- Dr Dan CondonThe team, from the University of St Andrews, has published its findings in the scientific journal Geology, after studying rocks in the west of Scotland, Ireland, Namibia and California. Drs Dan Condon, Tony Prave and Doug Benn say they have found evidence...

Five times in the last half a billion years, tremendous, global-scale extinctions have wiped out a significant fraction of life on Earth - and each of them presents a grand puzzle. The most recent and the most familiar is the extinction that wiped out the dinosaurs - between the Cretaceous and Tertiary periods, about 65 million years ago. But before that, 205 million years ago, was the "End-Triassic Event" - it set the stage for the Jurassic Period, which saw the rise to prominence of the dinosaurs. Just what happened that killed off half the species on the planet, though,...

A team from Harvard University presented a study this month that remnants from an ancient Earth exists, right now, inside contemporary Earth. The group believes that their comparisons of isotopic ratios of noble gases from materials deep inside Earth with those near the surface provide testimony that the deep-down material is actually from the Earth that existed before its massive collision with another planet. That immense impact – the largest in geologic history – is what many believe led to creation of the Moon. The currently favored theory about how the Moon originated says that it was formed 4.5 billion...

A snapshot of New Zealand's climate 40 million years ago reveals a greenhouse Earth, with warmer seas and little or no ice in Antarctica, according to research recently published in the journal Geology. The study suggests that Antarctica at that time was yet to develop extensive ice sheets. Back then, New Zealand was about 1100 km further south, at the same latitude as the southern tip of South America -- so was closer to Antarctica -- but the researchers found that the water temperature was 23-25°C at the sea surface and 11-13°C at the bottom. "This is too warm to...

THE world's sea levels fell in 2011 and it's all Australia's doing. New US research shows Australia's dry soil and mountainous coastline soaked up heavy rainfall in 2010 and 2011 and stopped it from flowing back into the ocean. That effectively halted a longterm trend of rising sea levels which have been caused by higher temperatures and melting ice sheets. "No other continent has this combination of atmospheric set-up and topography," scientist John Fasullo, who worked on the study, said in a statement. "Only in Australia could the atmosphere carry such heavy tropical rains to such a large area, only...