Basalt on EARTH Magazine

Columbia River basalts erupted faster than thought

Fri, 21 Dec 2018 10:49:09 -0500

Lava flows of the Wanapum Basalt, the second-youngest formation of the Columbia River Basalt Group (CRBG), are exposed in Palouse Falls State Park along the Palouse River in eastern Washington. Researchers recently found that most of the CRBG lava erupted over a period of about 758,000 years, faster than previously thought. Credit: Jennifer Kasbohm, Princeton University.

Editor’s note: This story appeared in print in the January issue of the magazine. The version below has been updated to note that the areal extent of the Columbia River Basalt Group (CRBG) exceeds 200,000 square kilometers. This value was previously given as 163,700 square kilometers. Additionally, the story has been amended to acknowledge prior research that suggested that more than 90 percent of the CRBG volume erupted over a roughly 1.1-million-year period.

Benchmarks: August 1975: Geotimes magazine inspires name of rock formation: A Q&A with Tony Alabaster

Fri, 20 Nov 2015 10:58:02 -0500

The pillow lavas pictured here on the cover of the August 1975 issue of Geotimes magazine were later named the Geotimes unit after the magazine. Credit: AGI.

In August 1975, an intriguing rock formation in Oman appeared on the cover of Geotimes magazine, EARTH magazine’s predecessor. This pillow lava — a type of rock that forms when hot molten basalt flows into water, such as happens in Hawaii, or erupts underwater — is one of the lowermost units of the now-famous Semail ophiolite sequence. Ophiolites, pieces of ancient oceanic crust and upper mantle later uplifted and exposed on land, were a hot geological topic in the 1970s, because they helped illuminate the process of seafloor spreading, a key puzzle piece supporting the then-revolutionary theories of continental drift and plate tectonics.

Did volcanism drive Earth into global glaciation?

Thu, 14 May 2015 11:52:20 -0400

Basalts like the Franklin Large Igneous Province, which blanketed much of modern Canada and Siberia during the break-up of Rodinia, may have plunged the Earth into global glaciation. Credit: Galen Halverson.

Between about 720 million and 635 million years ago, Earth suffered two big chills. During these “Snowball Earth” episodes, geologists think the world’s oceans froze over and glaciers spilled from tropical coastlines. Scientists have previously suggested that intense volcanism, unleashed by the disintegration of the supercontinent Rodinia, plunged Earth into these global glaciations. New research now lends support to this so-called fire-and-ice hypothesis.

The Syracuse University lava experiments

Fri, 17 Aug 2012 14:53:11 -0400

Pouring basaltic lava at Syracuse University's Comstock Art facility: Sheet-like, ropey pahoehoe flows over dry sand; infrared image of pahoehoe flow experiment with selected temperatures in degrees Celsius.

Pouring Lava

Melting a batch of the ancient basalt takes about four hours, but we hold the lava above its melting point for much longer to ensure that it is completely melted and to remove unwanted volatiles such as water. The lava is then poured at temperatures of 1,100 to 1,350 degrees Celsius, comparable to eruption temperatures of natural lava. We monitor it with a spot calorimeter and a Forward-Looking Infrared (FLIR) camera, the same instrument conventionally used at lava flows in the field.