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About This Gigapan

Taken by
Robin Rohrback Robin Rohrback
Explore score
Print Pricing
$6.00 to $1,105.00
1.30 Gigapixels
Date added
Dec 21, 2012
Date taken
Dec 20, 2012

There is one rock exposed along the Billy Goat Trail which is a bit more enigmatic. It is amphibolite, a metamorphic rock very rich in the mineral amphibole (a.k.a. hornblende), which shows up as black in this picture. The white portions of the rock are plagioclase feldspar. This is a very mafic metamorphic rock, with large crystals. Amphibolite occurs as large, folded tabular masses in the area of the Billy Goat Trail. An important question to ask here is "What was the protolith?" In other words, what were these amphibolites, before they were metamorphosed into amphibolites? Whatever it was had (1) a mafic composition and (2) large crystals. The answer which leaps to mind, I'm sure, is gabbro -- a coarse-grained mafic rock. Gabbro can occur as sills (large, tabular masses of mafic magma that squeeze between pre-existing sedimentary layers, in this case of metagraywacke), or it can occur as intrusive masses. If the latter, one place where we find a lot of gabbro is in the oceanic crust. If we interpret the amphibolite as being a metamorphosed slice of oceanic crust, then we are looking at the floor of the Iapetus Ocean here: the oceanic crust on top of which the graywacke was deposited!

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Stitcher Notes


GigaPan Stitch version 2.1.0161 (Windows)
Panorama size: 1301 megapixels (68044 x 19120 pixels)
Input images: 168 (21 columns by 8 rows)
Field of view: 86.9 degrees wide by 24.4 degrees high (top=3.6, bottom=-20.8)
Vignette correction off
Original image properties:
Camera make: Canon
Camera model: Canon PowerShot SX260 HS
Image size: 4000x3000 (12.0 megapixels)
Capture time: 2012-12-20 15:30:22 - 2012-12-20 15:41:56
Aperture: f/6.8
Exposure time: 0.0166667 - 0.1
ISO: 800 - 1600
Focal length (35mm equiv.): 502.6 mm
Digital zoom: off
White balance: Automatic
Exposure mode: Automatic
Horizontal overlap: 7.8 to 56.7 percent
Vertical overlap: 13.6 to 34.9 percent
Computer stats: 3996.82 MB RAM, 2 CPUs
Total time 56:36 (20 seconds per picture)
Alignment: 18:53, Projection: 3:31, Blending: 34:11
(Preview finished in 26:23)

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