The Hayward Fault one of, if not the, most active fault in California. Unlike it's rival the San Andreas Fault, which almost never moves, the Hayward fault slips constantly creating for some really interesting geology. What's even more interesting is that land developers believed it was a good idea to build houses literally right onto of an active moving fault. Some of these houses are crooked and jagged. Parking for this earth cache can be found at or neat the above coordinates. Please don't park in the driveways or block anyone in. This is a neighborhood too.
The Hayward Fault begins as the Calaveras Fault which begins at the San Andreas Fault about 20 miles south of famous Hollister, also known for it's fault creeps. A creep, in geology means a fault that is actively moving with little to no friction. This is due to the abundance of talc in the area. Talc is a natural rock that is rated a 1 on the rock hardness scale where on the other end, a diamond is rated a 10. The talc is then pressed together where it is broken down into a powder, acting as a lubricant for the fault to move whenever it receives a force from the earth.
Before I go into any more details lets first discuss the basic fundamentals of how fault lines are created and now they work. The answer can be found in your kitchen, literally. When boiling pasta on the stove, the hotter pasta floats to the surface then when it cools it sinks. This effect has a name. Convection currents in your pot at home and in the earth are nearly identical. There are a few difference though. One is with water, rather than boiling rocks and the other is that one is less a few inches while one is miles deep. Convection currents are continues cycles in the earth's mantel that make hotter rock rise, and cooler rock fall and the cycle begins over and over again. When this happens, it causes fractures in the earth's crust. When fractures occur, a fault line is created.
At this site you can observe something special along the Hayward Fault. Sometimes, or actually most of the time, the fault isn't just a straight line down the crust. It's jagged and at an angle. There are two types of these transverse (strike-strip) faults. One is called normal and the other is called reverse or thrust. The way to tell the difference is to see where the hangwall and footwall are in relation to each other. If the footwall is higher than the hangwall, then it's a reverse transverse fault. If the hangwall is higher than the footwall, than it's a normal transverse fault. Refer to the chart below that can give you a better sense of what to look for.
The Hayward Fault is a right lateral fault. This means, if you are on one side of the fault, looking at the other, the other side would move to the right relative to you.
Works Cited
http://www.decodedscience.org/hoodoos-desert-formations-help-understand-seismic-hazard/25297/2
http://pubs.usgs.gov/gip/earthq3/safaultgip.html
http://geomaps.wr.usgs.gov/3D4Dmapping/html/central1.html
TO LOG A FIND ON THIS CACHE YOU MUST GIVE ME THE CORECT ANSWERS BEFORE YOU LOG A FIND. YOU CAN CONTACT ME THROUGH MY EMAIL OR THE GEOCACHING MESSAGE CENTER. ANY INCORRECT ANSWERS WILL RESULT IN A DELETED LOG
1. "Hayward Fault - Fremont" on the first line of your email AND list all geocaching names of your party so I can match your answers to them. Note, this IS cheating as only the person who sent their answers has learned something, while the others get a "free ride". It's not fair to others. If you all want to learn something, I would prefer each cacher send me individual emails in the spirt of earthcaching.
2. While standing at the top of the hill at GZ, look north east towards Paseo Padre Pkwy. Use your GPS to describe the elevation difference from the top of the hill to the bottom.
3. Now, while at the bottom of the hill, estimate the angle of elevation to the top.
4. Look for signs of where the true Hayward Fault runs across Baylis Road. To find it, look for the offsets in the curb and sidewalk of Baylis Rd. If you walk more than 100 feet away from GZ, you are going too far. Once you find the fault compare where the fault is relative to the hill. Now using the strike slip chart above what would this section of the fault be considered as (normal, reverse, or strike-strip) AND your reasoning behind your conclusion. HINT: Think about how erosion would effect these different types of faults after a major slip and the location of the Hayward Fault is relative to the hill.
* NOTE - You will likely not receive an email back from me, unless I need clarification on your answers. Please, don't wait for me to tell you you have it correct or not. I do review your emails within 12 hours of getting them in my inbox and with other of my earthcaches, it has become too hard to do. As soon as you send the email, you can log this earthcache.