Tuesday, February 19, 2008

LIDAR map out lava flows in Grand Canyon

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 that dammed the river, then burst.

New airborne elevation survey data and radioisotope dating of Grand Canyon lava flows sheds new light on the battle between water and molten rocks there over the past 725,000 years.

Collecting data

To sort out all the lava flows, Crow and his colleagues used light detection and ranging (LIDAR) data that was originally collected for the Grand Canyon Monitoring and Research Center in the northern hemisphere spring of 2000.

The LIDAR survey data allowed the team to map out the lava flows in relation to sea level, making it easier to identify the tops and bottoms of the lava flows seen pasted on the walls of the canyons.

As for exactly how the lava dams worked, how far they backed up water and how violently they failed, that's all still largely a matter of conjecture.

"There are many possible scenarios and explanations for how the dams were formed or were destroyed, and it's likely that we'll never know them all," says Dr Cassandra Fenton, a geochemist at GeoForschungsZentrum Potsdam in Germany.

Fenton has studied what may be some of the largest lava dams in the Grand Canyon and their outburst floods."It makes you wish you could have been standing on the rim of the Grand Canyon watching it all happen when those lavas were damming the river, or see when the river finally overtook the dams," she says.

Source : http://www.abc.net.au/


Post a Comment