Smithsonian Science » geology

Slide Show: Smithsonian’s National Museum of Natural History is 100!

John Barrat — Tue, 22 Jun 2010 17:24:14 +0000

Since its doors first opened in 1910, the National Museum of Natural History has inspired curiosity and learning about the natural world and our place in it. Building upon the strong foundation of our extensive collections, the staff of the museum have been at the forefront of essential scientific exploration and research, and groundbreaking public exhibition and education. This slideshow and the website (www.mnh.si.edu/onehundredyears/) is a living documentary of the Museum’s 100-year history.

Geologist Liz Cottrell puts Eyjafjallajökull’s eruption into perspective

John Barrat — Mon, 17 May 2010 15:13:37 +0000

Smithsonian volcanologist Rick Wunderman talks about volcanos and the recent eruptions in Iceland

John Barrat — Fri, 30 Apr 2010 00:11:41 +0000

Keeper Tracey Barnes talks about the National Zoo’s Andean bear, Billie Jean, and her two new cubs

Smithsonian geophysicist Bruce Campbell explains his work of making a detailed radar map of the Moon

John Barrat — Mon, 28 Dec 2009 13:45:29 +0000

Smithsonian’s National Gem Collection acquires a yellow fluorite from Tanzania

John Barrat — Wed, 21 Oct 2009 17:52:20 +0000

The Smithsonian’s National Gem and Mineral Collection at the National Museum of Natural History has recently acquired a rare, intense yellow fluorite gem from Tanzania. “This is our first fluorite specimen from Tanzania,” Curator Jeff Post explains. “We acquired this specimen because it is a very nice quality fluorite with an attractive color and it is large enough to be exhibited. It’s a beautiful addition to our collection.”

Fluorite is well known and prized for its rich variety of colors, most commonly pale green, purple, yellow, orange, blue, pink and colorless. Most fluorite specimens have a single color but a significant percentage occur as a glassy, many-hued vein mineral. When a specimen is multi-colored, the colors are arranged in bands or zones. A specimen might have a clear outer zone allowing a cube of purple fluorite to be seen inside, or a single fluorite could have several different color zones.

Traditionally, fluorite is used as a flux in the manufacture of steel. It has also been used instead of glass in some high performance telescopes and camera lenses. Due to its relative softness it is not widely used by jewelers, but fluorite remains one of the most popular minerals for mineral collectors.

Widely occurring, gem quality specimens are found in Germany, Austria, Switzerland, Norway, Mexico, England, Canada, Kenya, Korea, Pakistan, China, Tanzania, and the United States. The intense yellow color and 40.01 carat size of the Smithsonian’s recently acquired fluorite specimen make it a rare and important addition to the Smithsonian’s National Gem and Mineral Collection. The stone is a gift of Dudley Blauwet, Blauwet Gems. —Jessica Porter

New Acquisition: With 1844 first edition, Smithsonian Libraries completes its collection of Charles Darwin’s three-volume geology series

John Barrat — Wed, 07 Oct 2009 11:22:10 +0000

Soon after Charles Darwin’s groundbreaking book On the Origin of Specieswas published in 1859, it found supporters among the staff of the Smithsonian Institution in Washington, D.C. Smithsonian Secretary Joseph Henry held the book in high regard. So did naturalist Spencer Baird, Henry’s right hand man and the second secretary of the Smithsonian, and Smithsonian naturalist George Brown Goode.

Image: 1840 portrait of Charles Darwin by George Richmond

As Darwin’s theories on evolution continue to guide scientific research at the Smithsonian today, it is fitting that Smithsonian Institution Libraries has recently acquired a rare first edition of Darwin’s Geological Observations on the Volcanic Islands, Visited During the Voyage of H.M.S. Beagle, published in London in 1844.

The volume completes the Smithsonian’s collection of Darwin’s three-volume series, Geology of the Voyage of the Beagle, which also includes the volumes: The structure and distribution of coral reefs (London, 1842) and Geological observation on South America (London, 1846). All three books are now on display in the National Museum of Natural History exhibit Darwin’s Legacy, which celebrates the 150th anniversary of the publication of On the Origin of Species (published Nov. 24, 1859).

In 1831, Darwin, a recent graduate of Cambridge University, embarked upon an adventure as an unpaid naturalist aboard the H.M.S. Beagle. The Beagle left Plymouth, England on Dec. 27, 1831, and after sailing around the world, returned to Falmouth, England on Oct. 2, 1836. The Beagle’s journey took Darwin to many places, including Tahiti, the Galapagos Islands, New Zealand and Australia. Darwin’s geological work aboard the Beagle brought him his first fame as a scientist. In Tahiti, he developed his theory of the formation of atolls. He proposed that these ring-shaped coral reefs form when the ocean floor gradually subsides beneath an island. The atoll remains after the island has disappeared below the surface of the water. Later investigations confirmed Darwin’s insights.

Photo: Darwin’s Geological Observations on the Volcanic Islands, Visited During the Voyage of H.M.S. Beagle, on exhibit in Darwin’s Legacy at the National Museum of Natural History.

Published nearly 15 years before On the Origin of Species, the book Geological Observations on the Volcanic Islands, Visited During the Voyage of H.M.S. Beagle, “is an important text in the development of modern geology and in the evolution of Darwin’s thinking on the formation of the earth and the distribution of species,” explains Leslie Overstreet, curator of natural-history rare books at the Smithsonian Institution Libraries. “SIL’s primary mission is to support the Institution’s scientists and historians,” Overstreet explains. “Global volcanism is a major focus of study at the National Museum of Natural History, and our holdings of published works form a deep, rich resource for researchers.” —Jessica Porter

Bombarded with ultraviolet light, the blue Hope diamond glows red

John Barrat — Wed, 19 Aug 2009 12:17:53 +0000

Some research is best done behind heavy, locked doors.

When geologist Jeffrey Post recently embarked on an experiment involving the Hope Diamond, at 45.52 carats, the world’s largest deep-blue diamond and one of the most famous and valuable museum objects on earth, he and his colleagues locked themselves and the diamond inside a large vault in the depths of the Smithsonian’s National Museum of Natural History.

Photo: The 45.52 carat, deep-blue Hope Diamond is shown here inside its surrounding pendant of 16 pear- and cushion-cut white diamonds. (Photo by Chip Clark)

Post was investigating a phenomenon that the millions of museum visitors who gaze at the diamond on its rotating pedestal behind bulletproof glass will never see—the mysterious red phosphorescent glow the stone emits when exposed to ultraviolet light.

The Hope Diamond’s red glow has long been considered a unique property of that stone. Most blue diamonds produce a bluish-white phosphorescence if exposed to ultraviolet light. The few other diamonds known to emit red phosphorescence were commonly assumed to have been from the even larger original stone from which the Hope was cut.

“It is something that always intrigued people,” says Post, curator of the Smithsonian’s National Gem and Mineral Collection. “For people who like the whole idea of a curse and that kind of story, the fact that this thing phosphoresces a bloody red color is just too good to be true.”

Photo: The Hope Diamond, right, without its white-diamond pendant, and the 30.62 carat Blue Hart Diamond.

Post timed his research to occur in the hours after the museum closed for the evening and before it reopened the next day. With guards standing by, the diamond was removed from its pedestal in the Harry Winston Gallery.

“We had a local jeweler come in and take it out of its setting for us,” Post says. (The jeweler returned early the following morning to reset the stone.) Next, Post and fellow diamond investigators from the U.S. Naval Research Laboratory, Ocean Optics Co. and Pennsylvania State University locked themselves in the vault with the diamond and a portable spectrometer.

“The clock was running,” Post says, and the scientists got to work. The diamond was positioned on a piece of clay inside a box that could be sealed to keep out ambient light. A fiber-optic cable connected to an ultraviolet light source was extended into the box and “pushed up against the top face of the Hope Diamond,” Post says. Then the diamond was exposed to ultraviolet light for several seconds.

When the light source was turned off, the diamond began to emit its characteristic red glow, a phenomenon that lasts several minutes. A second fiber-optic cable in the box channeled phosphorescent light from the diamond to the spectrometer.

Photo: The Hope Diamond emits a red phosphorescence after being bombarded with ultraviolet light. (Photo by John Nels Hatleberg)

Spectrometers measure wavelengths of light, and the display on a laptop computer hooked to the spectrometer revealed the Hope Diamond’s red light was more than just red. “That was the first time we had been able to see a display of what the phosphorescence spectrum looked like for the Hope Diamond,” Post says.

“We saw two strong peaks in the spectrum,” Post explains. One was in the red portion of the spectrum, “but the second peak, interestingly, was in the green portion of the spectrum.”

In the vault that night, the scientists also collected spectrum readings from other diamonds, including the second largest known deep-blue diamond, the 30.62 carat Blue Heart, also in the Smithsonian’s gem collection.

Later, Post and his colleagues hauled their portable spectrometer to New York City’s Diamond District, an area of Manhattan that is a center of the world diamond industry. A dealer known to Post granted the researchers access to dozens of valuable blue diamonds in his safe for further spectrum measurements.

The scientists learned that all blue diamonds show red and green peaks in their phosphorescence spectrum. But the relative intensity of those peaks and the rate at which they decay varies from diamond to diamond, leading to differences in the phosphorescent glow seen by the naked eye.

Diamonds are composed of carbon, and impurities in the carbon give rise to an individual stone’s color. Blue diamonds have relatively high levels of boron impurities but low levels of nitrogen. Post believes that the red phosphorescence emitted to some degree by all blue diamonds is likely due to interaction between those two elements. To test that possibility, he is continuing his study of blue diamonds, using a different kind of instrument that lets him measure the amount of boron and nitrogen in individual stones “and then correlate that with the particular spectra that we’re getting off those diamonds.”

Photo: Photographed through the thick protective glass of the Hope Diamond’s exhibition case, Jeffrey Post returns the diamond to its pedestal in the Harry Winston Gallery of The Janet Annenberg Hooker Hall of Geology, Gems, and Minerals in the Smithsonian’s National Museum of Natural History. (Photos by Chip Clark)

Post’s work has already yielded knowledge of interest not just to scientists but to diamond sellers and their customers. Because the relative intensity of the blue and red components of each blue diamond’s phosphorescence is unique, the same sort of analysis that the researchers did in the museum vault might be used to fingerprint individual blue diamonds and to distinguish natural stones from man-made ones.

No stranger to spectacular gems, Post still gets a thrill from working with the Hope Diamond. “Every time I look at it I kind of go, ‘My gosh!,’” he says, noting that it is impossible to overlook the stone’s “human history, the curse and the kings, the queens, the thefts.”

However, the scientist believes that his recent research underscores the famous diamond’s importance as “a unique natural history object.”

Astrophysical Observatory scientists are monitoring the mysterious movements of glaciers

John Barrat — Mon, 20 Jul 2009 08:00:56 +0000

In southeastern Greenland, two rivers of ice named Helheim and Kangerdlugssuaq flow in spurts and starts toward the coast. They are much like any other glacier, except each carries a network of scientific instruments that monitor their movements to the millimeter.

Geodesist James Davis, of the Smithsonian Astrophysical Observatory, in Cambridge, Mass., and his colleagues have watched the two glaciers since 2006. Their goal is to learn the details of how the glaciers move, and how they interact with earth and ocean in cycles affected by tides, temperatures, and a flock of other factors.

Photo: From a helicopter researcher Pedro Elosegui uses a laptop computer to download GPS data from Helheim Glacier. (Photo by G. Hamilton)

“I’m interested in getting a rich picture of what these glaciers are doing over several years,” Davis says. “We’re after details.”

And when he says details, he means it! The team uses a set of Global Positioning System receivers to gather data. You may be familiar with GPS as location guides for cars, hikers, and airplanes. A typical GPS is accurate to about three feet. Davis uses special receivers and analysis techniques to reach an accuracy of a fraction of an inch.

Davis is among a long line of Smithsonian scientists who have used space techniques to measure the properties of the Earth, such as its size, shape and the strength of its gravity field. In fact, Davis points out “the first models of Earth were developed in the 1960s at the Smithsonian Astrophysical Observatory, and are called the Smithsonian Standard Earth.”

The aim of modern geodesy is to study the dynamics of the Earth system, including the solid Earth, oceans, atmospheres, and cryosphere—glaciers and ice sheets. “The Smithsonian Astrophysical Observatory has played a leading role in this transformation of geodetic science,” Davis says.

Getting the equipment to the glaciers is no easy task. Everything has to be flown to the site. Helicopters are used for the last leg of the journey because glaciers aren’t smooth; they have cracks and crevasses that make it dangerous to land.

Photo: The calving front of Helheim Glacier. The ice in the distance is floating in the fjord. (Credit: M. Nettles)

The scientists set up the GPS receivers quickly, then leave them throughout the summer to record data. Then, they pick up the equipment and take the data back to the lab to analyze.

“We want to take data during the winter too, but the conditions become incredibly harsh,” Davis explains. “Power is an issue since we use solar power and the glaciers don’t get much sun during the winter at Arctic latitudes.”

Their efforts have uncovered some surprises. A glacier’s movement can change rapidly, speeding up or slowing down over a period of minutes. In particular, a glacier tends to speed up when it calves – that is, when a chunk of ice at the coast breaks off. In some cases, that “chunk” may be a mountain of ice four miles long and a third of a mile wide.

In separate studies, seismographs have detected rumblings that researchers dubbed glacier earthquakes. Davis and his colleagues found that all three – speeding up, calving, and seismic events – tend to happen at the same time. They are inter-related for reasons still unclear.

Photo: Smithsonian Astrophysical Observatory staff install a GPS station on Helheim Glacier. The GPS antenna is the round, white disk in the foreground. Flags are used to relocate the site at a later date. (Photo by G. Hamilton)

“These glaciers are very active – almost alive,” Davis says.

This summer marks the fourth year of monitoring for Helheim, and the second year at Kangerdlugssuaq. The team has funding from the National Science Foundation through 2010, but they hope to find additional funds to continue their work.

“There’s so much we still don’t understand,” Davis says.

Davis’s colleagues on the project are M. Nettles and G. Ekstrom of Columbia University; G. Hamilton of the University of Maine; and researchers at the institute for Space Sciences in Spain and the Danish national Space Center. —Christine Pulliam

Fossils Show Prehistoric Global Warming

John Barrat — Fri, 22 May 2009 12:52:32 +0000

The Past as Prologue
For those who think that global warming is a 21st-century phenomenon, Scott Wing, a scientist at the Smithsonian’s National Museum of Natural History, has news about the past.

Wing headed an international team of scientists whose discovery of plant fossils in the Bighorn Basin of northwestern Wyoming helps document the consequences of a sudden global warming, called the Paleocene-Eocene Thermal Maximum (PETM), 55 million years ago.

Experts believe the PETM, which was caused by a massive release of carbon into the atmosphere, may be an analogue for what is happening today as humans burn increasing amounts of fossil fuel and release large amounts of carbon dioxide.

Plant Movement Signals Global Warming
For nearly 15 years, Wing and his team dug through sediments deposited during uplift of the Rocky Mountains, looking for fossils of the right age and condition. Their discoveries proved that warming caused major shifts in the distribution of plants, allowing southern-dwelling trees and shrubs, related to poinsettia, sumac, and paw-paw, to move some 1,000 miles north in less than 10,000 years. These subtropical invaders flourished for about 100,000 years in what we now know as Wyoming. As carbon dioxide levels dropped and temperatures cooled again, plants related to birches and bald cypress came to dominate the vegetation.

The study and interpretation of this fossil record helps other scientists project future changes in plant life that may result from global warming induced by human activity.