Gunnison Point Overlook

Data 2012-04-21
Dystans 0.6 km0.4 mi
Czas 0h:18m
Zdjęcia 12

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Wykres (Kółko myszy powiększa)


Gunnison Point Overlook is located directly behind the Black Canyon of the Gunnison National Park visitor center.You can see the overlook from the visitor center.Along the short walk, mica flakes in the rocks sparkle in the sunlight.Pegmatite DikesOver a billion years ago, molten rock was squeezed into fissures forming the light-colored bands which thread Black Canyon's otherwise dark walls. You are standing on one of these bands. As the hot fluid slowly cooled and hardened, minerals formed into crystals. Look closely; you may recognize flecks of mica, feldspar, quartz, and perhaps even garnet.These bands of lighter colored igneous rock - called pegmatite dikes - are more resistant to erosion than the dark gneisses (sounds like "nice-es") into which they intrude.Consequently, the pegmatite weathers more slowly than the gneiss. The vertical position of the dikes here, combined with their resistance to weathering, has produced the fin-like appearance of parts of the canyon walls. You will see pegmatite at nearly every overlook.The pegmatite dike you see across the canyon nearly half a mile away is the same one you are standing on! Imagine the relentless cutting power of the Gunnison River.

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