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GRAND CANYON ROCK LAYERS THAT ARE SEEN ALONG THE COLORADO RIVER:
ROCK AGE(MY)
Kaibab Formation (Limestone)-----------------270
Toroweep Formation--------------------------------273
Coconino Sandstone--------------------------------275
Hermit Formation (Shale)--------------------------280
Supai Group (Formation)---------------------------315-285
Surprise Canyon Formation-------------------------330
Redwall Limestone-----------------------------------340
Temple Butte Limestone--------------------------385
Muav Limestone--------------------------------------505
Bright Angel Shale---------------------------------515
Tapeats Sandstone-------------------------------------525
Cardenas Lava---------------------------------------1250-1100
THE GREAT UNCONFORMITY
Dox Sandstone--------------------------------------1140
Shinumo Quartzite------------------------------------1195
Hakatai Shale---------------------------------------1200
Bass Limestone---------------------------------------1254
Grand Canyon Metamorphic Complex---------1750-1680
(Vishnu Schist and Zoroaster Granite)
THE GREAT UNCONFORMITY:
One of the great geological features of the Grand Canyon is The Great Unconformity. An unconformity is a gap in time between two rock layers where no rock layer is preserved. The Great Unconformity is found between the Vishnu Schist and the Tapeats Sandstone. It is so incredible because:
1. It represents a gap of 1.2 Billion Years
2. The gap is found throughout the world.
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3. It divides rocks with familiar fossils with those that have fossil bacteria or no fossils at all.
My Favorite Grand Canyon Geology Webpages:
