The Barry/Baker tunnel on Bunker Road will be closed for maintenance during the weeks of 6/2 and 6/9. The tunnel will be open on the weekends. Please use Conzelman Road instead. More »
Muir Beach Overlook closure
The Muir Beach Overlook will be closed for Accessibility improvements and trail upgrades from June 2 through July 21. Alternate viewpoints are available along Highway 1 between there and Stinson Beach.
Marin Headlands Rotation Animation
Do large blocks of rock rotate? Geologic evidence says they can, and do. Based on fault patterns and rock paleomagnetics, there is strong evidence that the Marin Headlands block has rotated clockwise about 130 degrees since these rocks were added to the edge of North America about 95 million years ago. No one knows when this rotation occurred, but it is likely to be related to movement along the nearby San Andreas fault in the last 10 million years. Right lateral movement along that fault is thought to have caused the clockwise rotation of other large blocks of rock, particularly in southern California.
Can rotation of this block be responsible for the modern geography of the Golden Gate Straits?
The animation requires your monitor to be set to at least 800x600 resolution and you must have Flash version 8 or greater installed to play. You can get the latest version of Flash here for free.
Did You Know?
Geologists sometimes call Franciscan pillow basalt “greenstone” because it contains green minerals formed in an interaction between the basalt and hot, mineral-rich seawater.