Saturday, February 16, 2008

Lava and Water Battled at Grand Canyon

Larry O'Hanlon, Discovery News
The Grand Canyon was not just carved by water -- it has also been the scene of periodic wars between the Colorado River and volcanic eruptions which dammed the river and then burst.
New airborne elevation survey data and radioisotope dating of lava the Grand Canyon's lava flows sheds new light on the battles between water and molten rocks there over the last 725,000 years.
Among the conclusions: Over that time there have been no less than four lava flows that dammed the river in the western Grand Canyon. Some of these dams were breached by dramatic floods and others may have been simply eroded away as the river flowed over their tops.