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EarthCache

Turtle Hill

A cache by caccbag Send Message to Owner Message this owner
Hidden : 3/14/2011
Difficulty:
2 out of 5
Terrain:
2 out of 5

Size: Size: not chosen (not chosen)

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Geocache Description:

Grand View Park, also referred to as Turtle Hill by local residents, is a small, elevated park in the Sunset District, San Francisco, California. It is surrounded by 14th and 15th Avenues, as well as Noriega Street.

Park is closed 10:00pm through 06:00am.

(From Wikipedia):

"Despite its small size of 4,500 m² (1.1 acres), about the size of a city block, the park is important geologically and botanically. It is also worth visiting because of the stupendous views it offers over downtown San Francisco, Golden Gate Park, to the Pacific Ocean, the Marin headlands, and across to the Sutro Tower.

The park covers the peak of a hill that rises to about 820 feet (250 m) above sea level. It is an outcrop of chert. Chert is a fine-grained silica-rich microcrystalline, cryptocrystalline or microfibrous sedimentary rock that may contain small fossils. It varies greatly in color (from white to black), but most often manifests as gray, brown, grayish brown and light green to rusty red; its color is an expression of trace elements present in the rock, and both red and green are most often related to traces of iron (in its oxidized and reduced forms respectively).

The chert contained here is part of the heterogeneous assemblage known as the Franciscan Formation, or Franciscan Assemblage, the primary geologic feature on which the city of San Francisco is founded, here covered with a thin layer of sand.Also known as the "Franciscan Formation," "Franciscan Series," "Franciscan Group," "Franciscan assemblage," or "Franciscan Complex," it includes altered mafic volcanic rocks (greenstones), deep-sea radiolarian cherts, greywacke sandstones, limestones, serpentinites, shales, and high-pressure metamorphic rocks, all of them faulted and mixed in a seemingly chaotic manner.

It provides one of the last remaining habitats within the city for a number of native plants, including the endangered Franciscan wallflower and dune tansy, and also bush lupin, beach strawberry, bush monkey flower, and coyote bush. The hill is topped with Monterey cypress trees, though these are now seen as damaging to the plant community.

Because of the fragility of the environment, visitors to the park are asked to keep to paths. "

To log your find, go to one of the signs posted at three locations in this park (for wheelchair access, there are two at street level - the other one is at the top where awesome views await you). Read the signs and e-mail the cache owner your answers to the following questions (do NOT post answers or photos that divulge answers in your logs...they will be deleted. You have 5 days after logging a find to send in the answers or the log will be deleted). Not all questions will be answered by the signs, you need to rely upon your own observations for others:

(1) What are the four "dune islands"?
(2) Explain to me why erosion is of such a high concern and what has changed in the area that gives rise to such a concern.
(3) Tell me if you can locate any fossils or fossil evidence and, if so, describe it.
(4) How old is the bedrock that underlies the hill and where was it originally formed?
(5) What transported the chert to San Francisco?
(6) Tell me some landmarks or points-of-interest that you can see from this park (this is not from the signs, but from your own eyes).

Additional Hints (No hints available.)



 

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184 Logged Visits

Found it 181     Write note 2     Publish Listing 1     

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Current Time:
Last Updated: on 1/4/2018 5:39:20 PM (UTC-08:00) Pacific Time (US & Canada) (1:39 AM GMT)
Rendered From:Unknown
Coordinates are in the WGS84 datum

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