Stories tagged earth science

We have lots of cool, clear water on our planet. But ever think about how it first got here? The folks at MinuteEarth have been thinking about that.

See video

May
23
2010

Climate science is hard

2010 (Jan - April) sets record for global warming
2010 (Jan - April) sets record for global warmingCourtesy NASA
Why can't scientists agree whether we are experiencing "global cooling" or "global warming" (Science Buzz covers both)?
I just spent a couple hours reading articles and comments about NASA's predicting that a new record global temperature will be set this year. Even though I have a degree in science education, I am overwhelmed by the complexity of the information.

  • Do temperatures taken down to 2000 meters below the surface give better results than down to 700 meters deep?
  • Are the thermometers used located too near the heated buildings?
  • How are large areas without temperature taking stations factored in?
  • One commenter questioned whether the heat contained by the ocean is measured in Joules per meter squared or joules per meter cubed (or should we use Watts per meter squared)?
  • What is the best way to measure a trend on a graph?

NASA scientists have this to say

Global warming trend: Anomaly means how much the temperature was above or below average.
Global warming trend: Anomaly means how much the temperature was above or below average.Courtesy NASA
NASA scientists just published a report on trends in global warming. Here is a link to a 34 page Goddard Institute for Space Studies (GISS) analysis of global surface temperature change Here is their conclusion and a graph from page 28.

Climate trends can be seen clearly if we take the 60-month (5-year) and 132-month (11-year) running means, as shown in Figure 21 for data through January 2010. The 5-year mean is sufficient to minimize El Nino variability, while the 11-year mean also minimizes the effect of solar variability. We conclude that there has been no reduction in the global warming trend of 0.15-0.20°C/decade that began in the late 1970s. pg 28

What I think

We have just had an extended period of minimum solar activity which should have had a cooling effect on the Earth (see our post Link between sunspots and weather explained). Increased solar activity will probably add even more energy. Warmer water means increased evaporation. Warmer air holds more moisture. So expect more extreme rainfalls (my sister experienced the Nashville flood of 2010) High temperatures mean higher energies so expect more violent weather (tornadoes and hurricanes).

Want more information?

Source article: Climate Progress

Nov
05
2009

A new exhibit featuring artwork by geologists, other earth scientists, and geoscience students is being presented this month at the Two Wall Gallery on Vashon Island, Washington.

Fabric art
Fabric artCourtesy Linda Hope Ponting
Geo sapiens, Geology and Art” could be the first-ever show of its kind, and will feature artwork from entrants from such places as the US, Canada, Great Britain, France, Australia, New Zealand, and Okinawa. Artwork includes sculpture, painting, photography and fabric art.

Block print
Block printCourtesy Greg Wessel
Curator Greg Wessel, who co-owns the gallery - and is also a working geologist - put out a call for submissions to geo-science websites and magazines.

Meteor Crater
Meteor CraterCourtesy Mark Ryan
"There is a lot of potential to generate works of art that exhibit the wonder and beauty of nature,” Wessel said. “Most geologists take a lot of photos, for example. But in addition, I'm looking for connections both in the brains of the geologists and in their conscious application of geologic themes to the creation of artworks."

Stone Sculpture
Stone SculptureCourtesy Bill Laprade
Wessel received nearly twice as many entries than his small gallery can hold but he promised to show as many pieces as possible. And I’m happy to report that a photograph by yours truly is included in the exhibit.

Geo sapiens, Geology and Art” opens tomorrow and runs though November. Vashon Island is located in Puget Sound about 8 miles from Seattle.

AAPG Explorer article
More Geo sapiens info

Dec
30
2008

Lava fountain: From the collections of the Hawaiian Volcano Observatory
Lava fountain: From the collections of the Hawaiian Volcano ObservatoryCourtesy USGS/Photo by J.D. Griggs
A drilling company in Hawaii tapped into a magma chamber giving scientists a first-hand view of geological processes never seen before.

The fortuitous discovery happened in 2005 when workers from Ormat Technologies, Inc were drilling in the Kilauea basalt fields off the Big Island. It took three years to analyze the data that was presented earlier this month at the annual meeting of the American Geophysical Union in San Francisco, CA.

The geothermal company had been searching for heat sources to create electric power for the Big Island when the drill suddenly broke through hard rock into molten rock. The magma chamber is thought to have been created by Kilauea activity during a 1950s or possibly even earlier in the 1920s.

“If we had hit molten basalt it would not be a big surprise,” said William Teplow, a geologist for the company.

But instead, the drill punched into a magma chamber just 2.5 kilometers beneath the ocean floor. While rising up the drill hole the top layer of red hot magma cooled quickly solidifying into a glassy rock, cuttings of which were gathered for examination. Looking at the shards of fresh rock, Teplow knew something was very unusual. Instead of the normal inky black glass that normally formed out of basalt, the new cuttings were clear and without color.

“It was very striking and we knew immediately that we had some anomalous body of rock,” Teplow said.

The samples were brought to geologist Bruce Marsh at John Hopkins University in Baltimore for study. Marsh determined they formed from dacite, a magma with a chemical composition between that of basalt (an extrusive rock that makes up most of the ocean crust) and granite (an intrusive rock which makes up most of the continental crust). The difference between the rock-types depends on the amounts and kinds of chemicals and minerals present.

Magma is subterranean molten rock that can reach temperatures as high as 1900 degrees Fahrenheit. When molten rock reaches the surface it's called lava.

"This is unprecedented; this is the first time a magma has been found in its natural habitat," Marsh said. "Before, all we had to deal with were lava flows; but they are the end of a magma's life. They're lying there on the surface, they've de-gassed. It's not the natural habitat.”

MAGMATIC DIFFERENTIATION

As magma cools different minerals precipitate out at different temperatures in a process called magmatic differentiation. This means rock that forms early in the cooling process is chemically different from the rock that forms during the middle or end of the process. Differentiation also depends on other factors, such as the melt’s original composition, contamination by wall rock encountered in its ascent, replenishment of the magma chamber, intermixing of different magmas, and the amount of volatiles (e.g. water and carbon dioxide). Watch an animated illustration here. The process is also known as Bowen’s Reaction Series from geologist Norman L. Bowen’s experimental studies in mineral crystallization in the early 20th century.

Essentially what happens is early in a magma’s cooling stage the elements magnesium and iron crystallize into mafic rocks (basalts and gabbros) forming the dense ocean crust. As the magma cools further, felsic rocks (high in feldspar and silica) form into the lighter granitic continental crust. In the theory of plate tectonics when an oceanic plate collides with a continental plate, the denser (mafic) oceanic crust slides beneath the lighter (felsic) continental crust in a process called subduction. The subducting material remelts into the mantle and the process starts again.

The discovery of the material could be the first time the actual process of differentiation of continental rock from older oceanic basalt has been observed in nature.

"As scientists, we've hypothesized about the nature and behavior of magma in literally countless studies, but before now, the real thing has never been found or been physically investigated in its natural habitat within the earth," Marsh said. “It's the difference between looking at dinosaur bones in a museum and seeing a real, living dinosaur roaming out in the field."

LINKS
Earthmagazine.org story
BBC website story
Origin of magmas
Videos of Kilauea volcano
More about magmatic differentiation
Hawaiian Volcano Observatory

Jul
26
2008

Gravitational compression

Will Earth ever freeze?: Internal radioactive decay is expected to keep Earth heated for billions of years.
Will Earth ever freeze?: Internal radioactive decay is expected to keep Earth heated for billions of years.Courtesy NASA
In its beginning, the Earth was so hot that it was entirely melted. That heat was generated because of gravitational compression. As gravity pulls materials in outer space towards each other they are compressed. When atoms and molecules are squeezed together they generate heat. Matter at the earth's center is very compressed; in fact, Earth is the densest planet in the Solar system.

Gravitational sorting

Penn State professor of geosciences, Chris Marone, feels that the original heat from that molten earth is only about 5 to 10 percent of the total heat within our planet. Another source of heat is from gravitational sorting.

In a gravitational sorting process called differentiation, the denser, heavier parts were drawn to the center, and the less dense areas were displaced outwards. The friction created by this process generated considerable heat, which, like the original heat, still has not fully dissipated.

Latent heat

Another source of heat is latent heat. When material in the center of the Earth changes from a liquid to a solid, heat is released. The solidified material also expands, which increases the pressure, thereby increasing the temperature. "The inner core is becoming larger by about a centimeter every thousand years," Marone says.

Almost all Earth's heat comes from radioactive decay

Marone says, the vast majority of the heat in Earth's interior—up to 90 percent—is fueled by the decaying of radioactive isotopes like Potassium 40, Uranium 238, 235, and Thorium 232 contained within the mantle. The amount of heat caused by this radiation is almost the same as the total heat measured leaving the Earth.

Source: Penn State University Live

Seismicity Map of the Caribbean
Seismicity Map of the CaribbeanCourtesy USGS
An unusually large earthquake hit the Caribbean island of Martinique today. Round up with lots of links here. First-person account by blogger here.