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File:Glen Canyon Park Chert Outcrop.jpg

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Captions

Captions

Outcrop of Franciscan radiolarian chert in San Francisco, California

Summary edit

Description
English: Roadcut revealing Franciscan chert rock, Glen Canyon Park, San Francisco, California.[1] This type of chert contains the skeletons of innumerable radiolarian creatures. It is a sedimentary rock, and the visible layering is due to the occasional inclusion of shale layers as the rock was deposited over millions of years.[2] The shale weathers more rapidly than the predominant chert, so the weathered rock looks like a stack. The remarkable folding of the stacked layers indicates the tectonic forces on this rock in this past, which warped the original planar layers into the fantastic shapes they now present. The road in the foreground is O'Shaughnessy Boulevard, which was constructed around 1935. This roadcut presumably dates from that time.[3]
Date
Source Own work
Author Eric A. Schiff
Camera location37° 44′ 19.18″ N, 122° 26′ 33.07″ W  Heading=270° Kartographer map based on OpenStreetMap.View this and other nearby images on: OpenStreetMapinfo

References edit

  1. ↑ Wahrhaftig, Clyde (1984) A streetcar to subduction and other plate tectonic trips by public transport in San Francisco, American Geophysical Union, pp. 29−32 ISBN: 9780875902340. See figures 24 and 25 in particular.
  2. ↑ Sloan, Doris (2006). Geology of the San Francisco Bay Region (University of California Press). ISBN 978-0520241268.
  3. ↑ San Francisco Recreation and Parks Department, "Significant Natural Resources Areas Management Plan," section 6.3 "Glen Canyon Park and O’Shaughnessy Hollow," (Final Draft Plan, February, 2006). This section contains several detailed maps on "Soils, Land Features, and Trails," "Vegetation," and "Sensitive Species and Bird Habitat." Retrieved February 3, 2007.

Licensing edit

w:en:Creative Commons
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This file is licensed under the Creative Commons Attribution-Share Alike 2.5 Generic license.
Attribution: Eric A. Schiff
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Under the following conditions:
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  • share alike – If you remix, transform, or build upon the material, you must distribute your contributions under the same or compatible license as the original.

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Date/TimeThumbnailDimensionsUserComment
current04:05, 16 April 2007Thumbnail for version as of 04:05, 16 April 20072,504 × 2,008 (2.17 MB)Easchiff (talk | contribs){{Information |Description=Outcrop of Franciscan chert rock, Glen Canyon Park, San Francisco, California. |Source=self-made |Date=April 15, 2007 |Author= Eric A. Schiff |other_versions= }}

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