Page 2 of 6
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
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.