GZ for this easy EC is at the end of Civic Center Drive in Fremont. The end of the road empties into the hilltop parking at the Fremont Civic Center. This hill is known as the Civic Center Knoll in various geological guides. As with any EC there is no physical cache. Log this cache when you've made the observations and email the answers to the one question below to the Cache Onwer.
This EC is first (from south to north) of a larger series of ECs all focusing on features of the Hayward Fault [this series is currently under construction, but individual ECs are being released sequentially to allow the largest number of cachers an opportunity for a FTF]. There is a final cache in the series (TBD) that can only be logged once you visited all the others in the series. Also, if you're interested in logging the final it is recommended you check out final in advance since observations you've made at this cache and other caches in the series will be helpful/required to log the final. Each of the ECs in the series contains slightly different information regarding the fault, with some overlap. Please see the Geotour for more information on this series (To be established).
The Hayward Fault is a splay off a the Calaveras Fault in the vicinity of San Jose, and the Calaveras Fault originates off the San Andreas Fault at a bend in the vicinity of Hollister (Figure of faults in the Bay Area http://i41.servimg.com/u/f41/16/31/61/01/haywar10.jpg ). The Hayward Fault starts in the vicinity of east of San Jose and extends at the foot of the East Bay Hills until disappears under San Pablo Bay at Point Pinole. The Hayward Fault is what is referred to as a right lateral strike-slip fault; this means that if standing on one side of the fault facing the other side of the fault, the opposite moves laterally (horizontally) to the right of the side your standing on.
GZ: When at GZ, look to a compass bearing of 111°SE you'll see the waters of Lake Elizabeth. This lake is a modified feature that use to be Stivers Lagoon. This lagoon is a sag structure created by movement on the Hayward Fault. Another but unrelated (directly) feature is Mission Peak with an enormous landslide below the summit.
If you look to a compass bearing of 158°S you will see a handrail on a handicapped ramp. Go there. Survey the knoll you're standing on. This is hill is a sausage shaped structure oriented northwest to southeast. Looking northeast you may recognize that this hill more or less lines up with the Tule Lagoon (GC4TAG1). Where the Tule Lagoon is a tectonic sag structure where a right-lateral strike-slip structure takes a right step resulting in a drop block. This knoll is part of the same zig-zag of the fault but a left step in a right-lateral strike-slip fault causes a "restraining bend" resulting in a compression structure, that is this hill. Here two traces of the Hayward fault are found at the base and parallel to the two long sides of the hill.
Question #1: From the high point of the hill, what is the elevation difference between the top of the hill and the surrounding terrain?
References:
Sloan, Doris and Donald Wells. 2006. "The Hayward Fault" [Field Trip Guide] Geological Society of America. Field Trip Guide 7.