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Billy Goat Trail > Lamprophyre Dikes on the Virginia Side, Visible From the Billy Goat Trail by Robin Rohrback

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Taken by
Robin Rohrback Robin Rohrback
Explore score
Print Pricing
$4.00 to $577.00
0.29 Gigapixels
Date added
Dec 20, 2012
Date taken
Dec 20, 2012

The Acadian Orogeny took place mainly to the northeast of here. (As the name implies, Acadian-aged rocks are well-exposed in Acadia National Park in coastal Maine.) Along the Billy Goat Trail, they left one set of important structures: a series of four parallel dikes filled with the igneous rock called lamprophyre. ("Lamprophyre" is a fancy name for what is essentially a mafic igneous rock, like more-familiar basalt or diabase). Biotite mica from these dikes has been dated using isotopes of potassium-40 and argon-40 to be about 360 million years old. It's worth noting that the mafic-composition rock which makes up the lamprophyre dikes is less stable than the older metagraywacke that it cuts across: as a result, it weathers out more easily -- making the dikes show up as a series of "slashes" in the surface of the rock face. This is a view of the Virginia side of the river, as seen from the Billy Goat Trail (which is on the Maryland side). Width of widest dike (second from left) is about two feet.

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Stitcher Notes


GigaPan Stitch version 2.1.0161 (Windows)
Panorama size: 288 megapixels (21428 x 13460 pixels)
Input images: 36 (6 columns by 6 rows)
Field of view: 23.8 degrees wide by 15.0 degrees high (top=6.3, bottom=-8.7)
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 12:58:59 - 2012-12-20 13:01:25
Aperture: f/6.8
Exposure time: 0.00625
ISO: 400 - 640
Focal length (35mm equiv.): 502.6 mm
Digital zoom: off
White balance: Automatic
Exposure mode: Automatic
Horizontal overlap: 10.2 to 17.8 percent
Vertical overlap: 28.2 to 32.5 percent
Computer stats: 3996.82 MB RAM, 2 CPUs
Total time 8:54 (15 seconds per picture)
Alignment: 3:11, Projection: 38 seconds, Blending: 5:04
(Preview finished in 4:31)

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