Texas canyon carved in just three days

Normally, geologic events happen over hundreds of thousands of years. In January, I was surprised to read that the Mediterranean sea may have filled with ocean water in a mere two years. (Check out that post at the Lay Scientist.)

Again--I am surprised to find that in a mere three days, floodwaters carved this impressive 2.2-kilometer-long and 7-meter-deep canyon in solid Texas bedrock. In 2002, a particularly menacing rainstorm sent water gushing over Canyon Dam in central Texas, carving this sizable trench which has since dried up significantly.

Now that the canyon and associated rocks and formations are visible, Caltech geologist Michael Lamb and Texas State geologist Mark Fonstad took a look at the area upstream of the flood, examining rock weathering patterns to measure strength of water movement, using aerial photographs and topological measurements to deduce displacement of rocks during the big 2002 gush. Because the flood was able to pop out massive rocks and carry them far upstream, the geologists deduced the rate of canyon erosion to be extremely rapid.

This study provides a promising scientific look into the mechanics of so-called megafloods since, unlike the filling of the Mediterranean sea, the erosion of the Canyon Dam canyon was witnessed in-vivo. Says geologist Mark Lamb:

"This is one of a few places where models for canyon formation can be tested because we know the flood conditions under which this canyon formed. We're trying to build models of erosion rates so we can go to places like Mars and make quantitative reconstructions of how much water was there, how long it lasted, and how quickly it moved."

Lamb, M., & Fonstad, M. (2010). Rapid formation of a modern bedrock canyon by a single flood event Nature Geoscience DOI: 10.1038/ngeo894

      Photo credit: Michael Lamb, Caltech