IMPORTANT:
This is an Earthcache. There is no physical cache at the coordinates provided. In order to log a "Found it" for this cache, you must send the answers to the questions below to the cache owner via the message center or email function of the site.
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Materials needed for this Earthcache: Camera, GPS
You may want to download the cache beforehand; cell signal can be spotty.
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Learning Objective: This EarthCache aims to teach you about the exposures of the Monterey Formation in Avila Beach and how these rocks formed.
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The Monterey Formation
The Monterey Formation is a sedimentary deposit from the Miocene period (a period of time ranging from about 23 million years ago to 5 million years ago). Being composed of sedimentary rock, the Monterey Formation was created from sediment deposits offshore. These deposits then hardened into rock, through a process called lithification. The formation is primarily composed of many fossils of microscopic ocean organisms, but it is also known for its exquisite preservation of larger marine life such as fish and shorebirds. As a result, the formation is primarily composed of shells of microscopic animals, which break down into very fine-grained siliceous shales. In addition, other minerals seep into the formation at times, such as iron, which gives it a reddish color. This shale is very valuable to humans, as it is what creates the oil fields offshore in this part of the California coast. The Monterey Formation is the major source rock for oil in California.
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Why Here?
Here on the Bob Jones Bike Trail, you can get a very special glimpse into the Monterey Formation, and notice some interesting properties of the formation in this particular location. This is a particularly visible exposure of the formation, making it perfect to study and observe, as it rises out of the ground right next to the path. In addition to the visibility of the formation, you can also see a unique property of the formation: how it is tilted. Sedimentary rock is formed in horizontal layers, as gravity pulls sediment to the bottom of the ocean, and it becomes compressed into rock. About 6-14 million years ago, the rock that had been created out of offshore sediment was lifted up by tectonic activity. Along what is now called the San Andreas Fault, tectonic plates pushed this marine sediment out of the ocean and it was moved onshore. As part of this movement, the formation became tilted, almost vertical, which you can see here. This section of the Monterey Formation that can be seen here has undergone less metamorphic activity than other areas of the formation, which allows you to very easily observe the layers in the rock.
The Monterey Formation as seen from the Bob Jones Bike Trail. Notice how it is tilted rather than horizontal. This is due to tectonic activity that rotated the formation.
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Questions
In order to log this Earthcache as a "Found it" you must send the answers to the following questions to the cache owner via the message center or the email function of the website. You do not need to wait for a response from the cache owner to write your log.
Logs without answers may be deleted without notice.
#1: If you are sending in answers for a group, include the usernames you are sending answers in for. If it is just you, simply put your username at the top of the message.
#2: Notice what direction the layers are going in the formation. Are they vertical or horizontal or somewhere in between?
#3: Did the layers initially form in this direction, or did they shift? What might have caused this rotation?
#4: Take a look at the grain size and texture of the rock. What can this tell us about how this was formed?
#5: Observe the colors of the rock. What minerals or geologic processes make these colors in the rock?
#6: Take a picture of you or a personal item at the coordinates for this cache. For example, a picture of your water bottle with the formation in the background will suffice, but just an image of the formation will not.