The Hayward Fault Walk
 in Central Park, Fremont
  joint project with Math Science Nucleus, City of Fremont, U.S. Geological Survey, California Geological Survey
 

Creating the East Bay Hills

The Hayward Fault is a strike-slip fault on the surface but changes to a low angle thrust fault as it descends under the Easy Bay Hills. This creates an uplift of the East Bay hills in the Fremont area exposing the rocks of the Briones Formation. Rocks of the Briones Formation are the most prominent rocks seen on exposed faces near Mission Peak and were deposited under marine conditions. They are composed of sandstone and many layers contain fossilized clams from the late Miocene Age (5-11 million years ago).   These rocks tell a story of large marine conditions and slowly the Hayward Fault started to uplift the area about 1.5 million years ago.  The environment changed as large rivers could no longer flow through the area.


The Hayward Fault is situated along the western base of the East Bay Hills which is part of the Diablo Range. From this point, you can see Mission Peak to your right. From the hills, the Hayward Fault travels through Central Park and back into the hills in the north part of Fremont (Niles).

                                                                                                                                                           




Notice the fossilization of shells in the rock.

Evidence from the Napa Earthquake helped researchers to connect the Hayward Fault in the East Bay with the Rodgers Creek Fault.  The main fault goes under the San Pablo Bay.

At depth the Hayward Fault merges into the southern part of Calaveras Fault near San Jose and dips toward the east, uplifting the East Bay hills. The Hayward Fault has subsidiary faults or offshoots of the main fault.


Color Key
Yellow - Calaveras Fault
Blue - Hayward Fault
Green - Subsidiary Hayward Fault
  
Regional Connections

 

 

 

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Math/Science Nucleus
 4074 Eggers Drive, Fremont, California, U.S.A., 94536
 (510) 790-6284
msn@msnucleus.org