Taxonomy term


Benchmarks: May 6, 1852: Edward Sabine links the geomagnetic and sunspot cycles

At the beginning of the 19th century, little was understood about Earth’s magnetic field, but interest in its workings had begun to grow, especially in Europe. That the magnetic field exists had long been recognized, and magnetic compasses had aided in navigation for centuries, particularly at sea where fixed landmarks are hard to come by. Not surprisingly, the increased attention emerging around the turn of the century came from naval and shipping interests, which recognized that an accurate understanding of the field’s behavior would be a boon to their fleets.

By this time, the underlying physical explanation for the magnetic field had also become a major source of scientific curiosity. In the preceding two centuries, observers had measured differences in the field’s intensity, inclination and declination — the angle between magnetic and true north — between locations, as well as changes in those properties at the same location, both over varying lengths of time. Others had noted the synchronized occurrence of colorful atmospheric auroras with widespread disturbances in the magnetic field, termed magnetic storms.

It was clear the planet’s magnetic field was an inconstant and complex phenomenon, and many eminent scientists saw it as the next great natural mystery to unravel.

13 May 2014

Mineral Resource of the Month: Selenium

Selenium, a relatively rare element with diverse uses, is widely distributed within Earth’s crust, but it does not occur in concentrations high enough to justify mining solely for its recovery. Selenium is recovered as a byproduct of nonferrous metal ore processing, principally from the anode slimes associated with electrolytic refining of copper. Slimes from primary copper refining can contain as much as 10 percent selenium, but are generally much lower.

12 May 2014

Energy Notes: December 2012-2013

Oil and petroleum imports data are preliminary numbers taken from the American Petroleum Institute’s Monthly Statistical Report. For more information visit

12 May 2014

Geomedia: California's climatic catastrophes detailed in "The West Without Water"

The 2013-2014 California drought has impacted everything from wildfires to food prices across the country. Politicians and the media called this the worst drought in California history, but scientists know that intense multiyear droughts are a regular feature of California’s climate. Fortunately, B. Lynn Ingram and Frances Malamud-Roam have put drought into context for everyone in their new history of California’s droughts and floods, “The West Without Water.”

12 May 2014

April 20, 1832: Arkansas' hot springs named the First National "Park"

In March 1872, not long after William Henry Jackson’s photographs from the famed Hayden Geological Survey first introduced the U.S. populace to the rugged majesty of northwestern Wyoming, President Ulysses S. Grant designated Yellowstone as the country’s first official national park. Some 40 years earlier, however, a comparatively small plot of land in Arkansas had garnered a similar designation, albeit in different terminology, from then-President Andrew Jackson.

20 Apr 2014

Mineral Resource of the Month: Wollastonite

Wollastonite, a calcium metasilicate, has an ideal composition of 48.3 percent calcium oxide and 51.7 percent silicon dioxide, but it can also contain minor amounts of aluminum, iron, magnesium, manganese, potassium, sodium or strontium substituting for calcium. Wollastonite occurs as prismatic crystals that break into tabular-to-acicular fragments. It is usually white but also may be gray, cream, brown, pale green, or red depending on its impurities and grain size.

14 Apr 2014

Energy Notes: November 2012-2013

Oil and petroleum imports data are preliminary numbers taken from the American Petroleum Institute’s Monthly Statistical Report. For more information visit

14 Apr 2014

Mineral Resource of the Month: Talc

When people think of talc, they often think of talcum and baby powder. However, these uses of talc are minor compared to its use in industrial manufacturing. The leading use of talc in the United States is in the production of ceramics, where it is a source of magnesium oxide, serves as a flux to reduce firing temperatures, and improves thermal shock characteristics of the final product. Worldwide, the major use of talc is as a paper constituent, where it fills the interstices between cellulose paper fibers, reduces paper transparency, improves ink receptivity, and absorbs undesirable tree sap residues that can generate blemishes in the paper.

03 Mar 2014

Energy Notes: October 2012-2013

Oil and petroleum imports data are preliminary numbers taken from the American Petroleum Institute’s Monthly Statistical Report. For more information visit

03 Mar 2014

Benchmarks: March 27, 1964: The Good Friday Alaska Earthquake and Tsunamis

During the Cold War, many Americans lived in fear of the day their town would be shaken by an atomic bomb blast. On Good Friday 1964, some Alaskans thought that day had come. Beginning at 5:36 p.m., intense ground shaking continued for almost five minutes as the most powerful earthquake ever recorded in North America struck 22.5 kilometers beneath Prince William Sound, where the Pacific Plate is subducting beneath the North American Plate. The shaking — felt over an area of more than 1.3 million square kilometers — was so severe and long-lived that some survivors later said they first thought the Soviet Union had dropped a nuclear bomb on Anchorage, 120 kilometers northwest of the epicenter.

27 Feb 2014