Berkeley ridgeline

If you have walked up to this point, time to catch your breath! Use the sign to orient yourself northward for a close look at the Berkeley ridgeline. Try to find Grizzly Peak and Bald Peak (the latter may be referred to as Vollmer Peak on the sign). The East Bay Hills have risen over the last couple of millions of years, and they are a product of the complex dynamics of local tectonic forces. The East Bay Hills are bounded by the Hayward Fault to the west and the Calaveras Fault to the east, with many local subsidiary faults. The movement of each of the East Bay faults generally reflects the strike-slip nature of the larger San Andreas Fault system, with the western block moving to the northwest and the eastern block to the southeast. However, the faults are not perfectly in parallel, and the combination of transverse and compressive motion leads to transpression, and the transpressive forces crumpled the East Bay landscape, much as your shirt sleeve acquires ridges and valleys when you push it up. As a result of all the folding, the originally horizontal sedimentary layers now form humps and troughs, and some of the rock layers are even vertical in orientation. The rocks of Sibley are part of a trough, or syncline, where the layers tilt down toward the east.