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A climate change solution?

Beneath the Columbia River Basin, a real-life trial of the uncertain science of carbon sequestration – Part I

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Among the types of rock being investigated for carbon sequestration is McGrail's focus: flood basalt. Most sequestration experts think basalt sequestration a rather quirky, even quixotic idea. After all, most of the country lacks the layered volcanic flows that spread to form the Columbia and Snake river plains.

But basalt has one virtue that other geologic formations lack. In the laboratory, it can transform CO2 into calcium carbonate — the equivalent of seashells or limestone — in a matter of weeks or months, effectively immobilizing carbon in a solid. And because most of the Pacific Northwest is awash in basalt, carbon sequestration of this type could be an excellent regional method of reducing carbon dioxide emissions — if what happens in the lab can be made to happen 3,000 feet below the Columbia River Basin.

Basalt is a majestic rock, a deep black when young that gradually weathers into softer colours, especially the telltale reds that show where iron in the stone has reacted with oxygen. Depending on how it cools, basalt sometimes forms huge or tiny vertical columns — Wyoming's Devils Tower and the Giant's Causeway in Northern Ireland are prominent examples of the big versions. The Whistler area has several pockets of basalt columns. In Washington state, one of the best places to see large-scale columnar joining is in the Columbia River Gorge 200 miles west of Richland, where massive columns rear above Interstate 84 as it snakes alongside the river. In the rain-drenched climate west of the Cascades, the stately columns are graced with conifers and ferns, waterfalls and rockslides that are very different from the drab flats and tortured hills in the heart of the Columbia basalt to the east.

As they erode and break down, volcanic rocks form rich soils abundant in minerals. Late in the 19th century, when early boosters like the Spokane newspaper and the railroads dubbed the area the "Inland Empire," the Columbia basalt area drew optimistic would-be farmers. Except for wheat, however, dryland farming was a bust. Not until the dams sprang up on the Columbia and large-scale irrigation became possible did farming expand in a big way.

The centre of McGrail's interest lies in this area and in the Columbia River Basalt Group, which consists of about 300 lava flows that ran fast and often in the Miocene epoch between 6 million and 17 million years ago. It covers about 65,000 square miles, in places to a depth of three miles; some of the crustal rifts disgorging the basalt were as much as 100 miles long. Because the lava gushed out and spread horizontally, on a relief map the flood basalt region looks like it has been ironed out compared to the mountainous topography surrounding it.