By Carl Zimmer
http://www.wired.com/science/discoverie ... ction_0307
Three geologists from the University of New Mexico have explored caves along the Grand Canyon, ranging from the very bottom to the rim. In this week's issue of Science, they report that the highest caves have mammilary coatings dating back about 17 million years, and the lowest ones date to about 800,000 years. And all the caves between the top and bottom have the intermediate ages you’d expect. By measuring the distance from the rim to the caves, the geologists were then able to estimate how fast the Colorado River carved the canyon. The downstream end of the canyon formed first, and only later did the upstream end catch up. These new measurements show that even as the river sank down into the earth, the earth itself rose, lifted by hot rock welling up through the crust.
The Grand Canyon is far older than Noah's flood, but at just 17 million years or so, it’s geologically infantile. For 99.99 percent of Earth's history, the Grand Canyon as we know it did not exist.