Tafoni of the Sandstone Caves EarthCache
Tafoni of the Sandstone Caves
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As an earthcache, this does not involve finding a container. Rather, the small caves, columns, and honeycomb formations are the cache. Enjoy the area. Think about its geology. And answer the logging questions below.
Geology
The rocks in this area is part of the Vaqueros Sandstone geological formations, formed when the area was a deep marine basin, far below the ocean surface. As sand eroded into the basin, it mixed with microscope shells (calcium carbonate) to form sandstone. The movement of the North American Plate and Pacific Plates in turn pushed the rocks up as the Santa Cruz mountains were formed.
Geologists first used the word "tafoni" to describe formations on the island of Corsica. The formations found on this site are part of a complex weathering process that begins in the rainy season when water soaks deep into the sandstone and mixes with the calcium that is there. When the water dries, some of the dissolved calcium is drawn to the surface of the stone and forms a hard outer layer of duricrust.
The evaporation process causes the remaining calcium to be distributed unevenly so that there are some soft areas that have little calcium and some hard high-calcium areas. If the hard part of the surface cracks, the softer areas erode away creating the tafoni formations. The intricate patterns result from the different erosion rates of the hard and soft areas.
Logging Requirements
To get credit for this cache, send the owner an email that identifies the name of this earthcache with the following information that is found at the observation deck near the formations. Please email me through my profile rather than use the message center.
- What is the term for the weathering process that created the formations? Do you think that this process is continuing today? Will more of the tafoni formations be created over time or will the area simply erode in other ways?
- What are the names for two kinds of tafoni formations that are found at this site?
- Photo Requirement: Post a photo taken at the site. Under the June 2019 guidelines, you need not be in the photo but it should otherwise include your gpsr, a personal item, or an information sign that does not sHe any answers.
Please submit your answers before logging this as a "find." Logs that have not fulfilled the logging requirements will be deleted.
More Information
For more information about the preserve (including trail maps), please visit the Midpenninsula Regional Open Space District.
When visiting the area, please do not touch or climb on the formations since they are delicate and easily damaged.
Special thanks to geekster for his cooperation in placing this earthcache near his excellent Tafoni traditional cache, which first brought us out to this site.
Additional Hints
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Treasures
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