Faulting at Devils Slide

Strata at Devils Slide

The opening of the tunnel around Devil’s Slide in San Mateo County allowed for the creation of a mile-long trek to look at some of California’s fascinating geology. In my last geology hike to the trail, I took a photo of the great sedimentary layers at the north end of the trail, then edited the photo to show how well the strata line up on each side of a fault through the sediments. Mouse over the image below to see the image of the current conditions of the strata.

Imagine the strata lined up like this years ago. The red arrow shows the relative motion of the rocks between "then" and now.Hover your mouse over the image to see the current condition of the strata.

After faulting


After pressure and faulting, the strata now looks like this. Slide your mouse back and forth over the image to see the change.

The video below includes a great description of the geology of the area. Click on the “Sedimentary Layers” link to see the main section on the geology.

More resources on the geology of Devil’s Slide:

Mt. Diablo beacon to be lit in commemoration of Pearl Harbor attack

This Sunday, December 7th, 2008 (and each year on December 7th), the beacon atop Mt. Diablo will be lit at dusk in commemoration of the attack on Pearl Harbor on December 7th, 1941. After the attack, blackouts in the Bay Area caused the beacon to be turned off, and after the war it was not turned back on.

“Since 1964, the Diablo Valley Pearl Harbor Survivors Association has lit the old aircraft beacon atop Mt. Diablo every Dec. 7 in remembrance of those lost on that “day of infamy” and throughout World War II. Sunday at dusk, look to Mt. Diablo for the beacon that was turned off on Dec. 7, 1941, and not relit until the first memorial ceremony at the top of Mt. Diablo in 1964.” From http://www.insidebayarea.com/trivalleyherald/localnews/ci_11102595

A bit more info on the beacon can be found here: http://www.savemountdiablo.org/DiabloWatch/2003FallDiabloWatchSP.pdf