Now comes the 'rock porridge'

Over the weekend, La Crescenta author Bernadette Murphy had a nice opinion piece in the L.A. Times invoking John McPhee and his seminal writing on debris flows out of the tectonically young San Gabriel Mountains. I've mentioned McPhee's work before — the imagery of his reporting stays with me — and after the recent Station Fire, Murphy discovered that her walking route stars in "Los Angeles Against the Mountains," McPhee's chapter on the San Gabriels in his 1989 book, "The Control of Nature." He got her attention:

"The dark material coming toward the Genofiles was not only full of boulders; it was so full of automobiles it was like bread dough mixed with raisins. On its way down Pine Cone Road, it plucked cars from driveways in the street. When it crashed into the Genofiles' house, the shattering of safety glass made terrific explosive sounds ... ."

McPhee describes a nightmare. Debris spilled through the house, trapped the Genofiles, flowed over the roof. The house filled in six minutes. "The mud stopped rising near the children's chins."

Good timing. Today, the U.S. Geological Survey issued what the Times calls "a grim forecast for foothill communities hit by the Station fire, saying huge mudslides and debris flows are highly likely during the winter rainy season." Says USGS geologist Susan Cannon: "Some of the areas burned by the Station fire show the highest likelihood for big debris flows that I’ve ever seen." You can read the whole report at the USGS website. It has maps predicting debris leaving the mountains and reaching Foothill Boulevard even in a typical year's storm sequence. If there's a huge rain winter like in 1978, watch out.

Map: USGS report