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Virtual Vista: Grenville Dome, Wyoming, USA

Visualizing and understanding geologic structures is one of the most challenging tasks facing students in introductory geology courses. In order to comprehend geologic structures, it is necessary to practice your skills at 3-dimensional visualization.

Digital technologies are a marvelous way to illustrate the complex 3-dimensional relationships of strata in geologic structures. A picture may be worth a thousand words, but a good picture of a geologic structure is priceless.

The image below shows Grenville Dome, a small doubly plunging anticline located near Sinclair, Wyoming, USA. This image was generated using a computer to process a digital elevation model (DEM), then a digital aerial image was mapped to the surface to produce this wonderful 3-dimensional image.

<a onClick="window.open('/olcweb/cgi/pluginpop.cgi?it=jpg::::/sites/dl/free/0072826967/30425/VirtualVista1501.jpg','popWin', 'width=NaN,height=NaN,resizable,scrollbars');" href="#"><img valign="absmiddle" height="16" width="16" border="0" src="/olcweb/styles/shared/linkicons/image.gif"> (139.0K)</a>

You can imagine the scale of this structure by noting the 4-lane interstate highway in this image just north of the structure. Also, the small town of Sinclair, Wyoming.

The image below is a close-up virtual view of the Grenville Dome. In this image, it is evident that the exposed strata are inclined (dipping away from the center of the structure). Note that the pattern of stream erosion creates v-shaped notches in the outcrops, and the "v" points in the direction of plunge. Which strata do you think are oldest in this view? Which are the youngest? How would you measure the strike of these strata?

<a onClick="window.open('/olcweb/cgi/pluginpop.cgi?it=jpg::::/sites/dl/free/0072826967/30425/VirtualVista1502.jpg','popWin', 'width=NaN,height=NaN,resizable,scrollbars');" href="#"><img valign="absmiddle" height="16" width="16" border="0" src="/olcweb/styles/shared/linkicons/image.gif"> (116.0K)</a>

Folds such as this record intervals of geologic time when tremendous tectonic stresses occur within the lithosphere. Folding like this is often associated with large scale mountain building events driven by Plate Tectonic processes. Thorough analyses of folds across a geographic region can yield a good deal of information about the geologic history of that area.

 

Click on the link below for a virtual overflight of the Grenville Dome

Grenville Dome WY Fly By (1841.0K)

Points to Ponder:

1. Print a copy of this page and label the images to show the orientation of tilted strata (strike and dip) around the Grenville Dome.

2. Discuss with your instructor how a structure like the Grenville Dome formed.

Having trouble loading or viewing the video clip? You will need the DivX video codec for your media player to watch the video. The DivX codec is available free from www.divx.com. Click on the link or type the URL into your browser to go to the DivX download site. Once at the DivX site, follow the "DOWNLOAD" links until you locate the download "Standard DivX Codec (FREE)" hyperlink. Click on the link and download the small DivX codec file. The codec file may take a few minutes to load. Please be patient. Once the file is downloaded to your local computer, double click on the file to automatically install the Divx codec.

You may also discover that the Virtual Vistas work best with the Windows Media Player, available as a free download from www.microsoft.com. Click on the link or type the URL into your browser to go to the Microsoft web site. Once at the web site, type "windows media player" into the Search box, then click on the appropriate link to download the latest version of Windows Media Player.








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