National Geographic News

Gneiss Lines

Photograph by Marli Miller, University of Oregon

As if an avant-garde painting, younger white rock intrudes in a tapestry of gneiss. Since the white rock doesn't show the same evidence of folding as the surrounding gneiss, it offers proof that it is a younger intrusion. Gneiss, a metamorphic rock, can be commonly found in Precambrian areas. Note the penny for scale.

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