San Juan Capistrano Earthquake & Reservoir EarthCache
San Juan Capistrano Earthquake & Reservoir
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Welcome to Historic San Juan Capistrano. There is no physical container for this cache, but there is a traditional on the other side of the park, just a few feet away.
The above coordinates bring you to a geological and archaeological site. All the answers can be found using the plaque, "Mission Yard and Reservoir Site" and the surrounding areas. In order to log this cache as a find you will need to answer the questions and email me the correct answers. Any incorrect answer will result in a deleted log.
Plate Tectonics are very interesting to most geologists (and some geocachers). Pangaea was the biggest continent to ever form on planet Earth. It broke apart about 200 Million years ago and formed seven new continents called Africa, Antarctica, Asia, Australia, Europe, North and South America. Now, in a few more millions of years, these continents will form again to become a second Pangea.
Along these very large continents there happens to be many thousands of fault lines and several tectonic plates. These plates are in constant movement caused by convection currents in the magma of earth's mantel which is in constant circulation (heat rises, then cools then sinks, and so fourth). This action moves the plates around the earth as they travel above the outer mantle. It is very similar to boiling oatmeal on the stove. Some faults located within the plates are caused by the stresses that build up and eventually crack the crust. For example, Death Valley is not on a plate boundary, but it has many fault lines to make it the lowest elevation point on land in the continent. Others, including what you would witness in the San Andreas Fault. This is where two adjoining plates meet. The three main types of faults are subductive (forces push an edge into and under the other), transverse (forces push one side length-wise sliding against the other), and sea floor spreading (spreading in the crust - the sides move away from each other). The San Andreas Fault is a transverse fault zone.
The San Andreas Fault is located at the border line between two tectonic plates called the North American Plate and Pacific plate. The North American Plate spans over half of California through half of Iceland. It is all the land north and east of the San Gabriel Mountains and Carrizo Plane. The Pacific Plate spans from the other half of California all the way to the eastern shore of Japan. everything south and west of the San Gabriel Mountains and Carrizo Plane. The San Andreas Fault starts in the Gulf of California in Mexico and ends just a few miles south of Eureka, California for a total of about 800 miles! This fault is the most famous fault of all because of the earthquakes it causes. About 100 earthquakes a day are measuerd along the San Andreas Fault! It is a dangerous fault because of all the deadly earthquakes it causes like the one during the World Series in California in the 1989. Geoloists are predicting a major earthquake along the San Andreas Fault, about a 7.5 to an 8.0 on the southern end of the fault (Southern California). History has shown that a major earthquake erupts along this area about every 100 years. The last major quake in the Southern California region of the San Andreas was the 7.9 Fort Tejon quake 1857 which was felt from Los Angeles to San Francisco. We are over due!!
This fault was named after geologists found the fault in Lake San Andreas up in San Fransico. Lake Palmdale was and still is a huge sag pond made by the San Andreas Fault. A sag pond (in this case) when an underground river leaks up towards the surface of the Earth. Lake Palmdale was also formed by the San Andreas Fault.
Now for the history of the fault and how it ties in to San Juan Capistrano.
The earthquake that cause The Great Stone Church section of the mission to collapse happened on the morning of December 8, 1812. It measured about a 6.9 on the Richter Scale. Considering that the one in '89 was only around a 7. Its epicenter occurred on the San Andreas Fault in the Tejon Pass which is where Interstate 5 passes through the San Gabriel Mountains. In all, 40 Native Americans were killed because of the collapse. A lot of you geocachers might be asking about if the San Andreas Fault passes though here and it doesn't. Sorry, it's not my fault!
The ruins for the collapse were moved to this site, which is on public land. For one of the questions, you will have to investigate further, but for now you can continue learning from this webpage. During an earthquake the ground shakes along the X, Y, and Z planes. The ground moves front to back, left and right, and up and down. If you see cracks in the rocks and they are pointing in the same directions, then this means that they were shaken by an earthquake. If they are scattered this means that most likely the heat from the sun dried them out.
Now, this site in the early 1900's used to be a natural reservoir. The ground had a depression which would collect water during the rainy seasons of December and January, but also during off season when the San Juan Creek would be at high tide. There may have been a dam here to make less water escape into the creek. To have more water be added into the reservoir archeologist believed that a nearby natural spring may have added to the capacity. Although a spring was never found, it may be dormant for many years before it erupts again. There is also that possibility that it may never erupt again, or that there was never a spring at all. But what we do know is that this reservoir was created by a depression in the ground.
Depressions are formed when the ground below can no longer support the ground above. Gravity takes over and the ground literally falls on top of itself. Sinkholes work a similar way, but these aren't sinkholes. Another way that they can form is from an active fault zone. Now the closes known fault zone to the area is the Newport Inglewood Fault and that is in the Pasific Ocean so we know that it can't be a fault line. We can factor out Lava Tube since there are no volcanoes around here. The best bet is to say that is was caused by loose sediment either from the spring or the San Juan Creek. Overtime the sediment on the bottom liquified and the sediment on the top hardened and it just collapsed. BOOM, we have a natural reservoir, just like that. This reservoir served the people who lived here as a place to swim, and a place to drink. That sounds harsh, but that was before we knew about the health hazards.
You can read more about this at the histoical maker at the above coordinates. I don't want to copy and past from it, so I'll let you have the fun into discovering it all on your own.
The following are my cited sources. I got the information from there, but did not copy.
(visit link)
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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. San Juan Capistrano Earthquake & Reservoir on the first line of your email.
2. Look for any of the debris that is from the Great Stone Church. They are large rocks/boulders. Use the historical marker to help you locate them. What are the colors, size, and do you see any crack formations or groove indents? If so, are they pointing the the same direction and what does this tell about the building materials used in the original construction?
3. Look at the photo on the historical marker. You can see the ruins of the Great Stone Church and other areas as well. In your opinion to the picture, why do you think the Great Stone church was the only thing damaged or not left standing? Hint: Think about the architecture, design, tallness, ect in relation to the other parts of the picture. Remember that earthquakes creates X, Y, and Z waves.
4. Look at the map on the historical marker and find where the reservoir, or "pond" as it says on the plaque. In your opinion, where do you think the source of water was from? Look at the closest source of water to the reservoir site, keeping in mind of elevation changes that are not included on the map. Everything is labeled so support your answer from this map.
* 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 you 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.
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