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The Grand Canyon Tells the Story of North America

The Grand Canyon Tells the Story of North America Knowing how and where rocks are formed allows us to read the story written in the rocks. A mile thickness of rocks of the Great Plains are exposed by uplift and erosion by the Colorado River. Rocks of the Grand Canyon

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The Grand Canyon Tells the Story of North America

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  1. The Grand CanyonTells the Story of North America Knowing how and where rocks are formed allows us to read the story written in the rocks. A mile thickness of rocks of the Great Plains are exposed by uplift and erosion by the Colorado River.

  2. Rocks of the Grand Canyon Separate the larger puzzle into a series of smaller puzzles (I.e., each group of rocks) • Metamorphic rocks (oldest) • Intrusive igneous rocks • Sedimentary rocks lying on an irregular metamorphic surface • Sedimentary layering • Erosion of the canyon (Youngest event)

  3. Rocks of the Grand Canyon Each group of rocks is separated by a gap in the geologic record (formations and contacts) • Metamorphic rocks  Metamorphism • Granite  Intrusion of silicic magma • Eroded surface  Uplift and erosion • Sedimentary rocks  Shallow inland seas • Erosion of the Canyon  Recent uplift

  4. Metamorphic and Igneous Rocks • Metamorphism of sedimentary rocks • Igneous intrusion during later stages of metamorphism (during mountain building) • Uplift and erosion (during and after mountain building) (nonconformity)

  5. Sedimentary Rocks • Deposition of sediments on eroded metamorphic and igneous rocks. • Uplift and erosion exposing sedimentary layers and • Eventually expose Igneous and metamorphic rocks again G Uplift and Renewed Erosion

  6. Erosion and Exposure • Uplift and erosion exposing sedimentary layers and • Eventually Igneous and metamorphic rocks again G Uplift and Renewed Erosion G Uplift and Renewed Erosion

  7. Formation of the Grand Canyon Sandstone 350 Shale 380 Limestone 450 Million Years Old 300 million years ago

  8. Regional Uplift, Tilting (or folding), Erosion Formation of the Grand Canyon Erosion Sandstone 350 Shale 380 Limestone 450 280 million years ago Regional Uplift Tilting (or folding)

  9. Regional Uplift, Tilting (or folding), Erosion Formation of the Grand Canyon Erosion Sandstone 350 Shale 380 Limestone 450 270 million years ago Regional Uplift

  10. Regional Uplift, Tilting (or folding), Erosion Formation of the Grand Canyon Erosion Sandstone 350 Shale 380 Limestone 450 260 million years ago Regional Uplift

  11. Regional Uplift, Tilting (or folding), Erosion Formation of the Grand Canyon Erosion Sandstone 350 Shale 380 Limestone 450 250 million years ago Regional Uplift

  12. Regional Uplift, Tilting, or folding) causes Erosion • Erosion surface indicates gap in geologic record Formation of the Grand Canyon Sandstone 350 Shale 380 Gneiss(1,500) Granite(280) Limestone 450 Gabbro (790) 240 million years ago

  13. Regional Uplift, Tilting (or folding), Erosion • Erosion surface, gap in geologic record • Continuous Sedimentation Formation of the Grand Canyon Sedimentation (e.g., clay) Sandstone 350 Shale 380 Gneiss(1,500) Granite(280) 450 Limestone Gabbro (790) 220 million years ago

  14. Regional Uplift, Tilting (or folding), Erosion • Erosion surface, gap in geologic record • Continuous Sedimentation Formation of the Grand Canyon Sedimentation (e.g., lime mud) Shale (220) Sandstone 350 Shale 380 Gneiss(1,500) Granite(280) 450 Limestone Gabbro (790) 210 million years ago

  15. Regional Uplift, Tilting (or folding), Erosion • Erosion surface, gap in geologic record • Continuous Sedimentation Formation of the Grand Canyon Sedimentation (e.g., quartz sand) Limestone (210) Shale (220) Sandstone 350 Shale 380 Gneiss(1,500) Granite(280) 450 Limestone Gabbro (790) 200 million years ago

  16. Regional Uplift, Tilting (or folding), Erosion • Erosion surface, gap in geologic record • Continuous Sedimentation Formation of the Grand Canyon Quartz Sandstone (200) Sedimentation (e.g., immature sand) Limestone (210) Shale (220) Sandstone 350 Shale 380 Gneiss(1,500) Granite(280) 450 Limestone Gabbro (790) 190 million years ago

  17. Regional Uplift, Tilting (or folding), Erosion • Erosion surface, gap in geologic record • Continuous Sedimentation Formation of the Grand Canyon Quartz Sandstone (200) Arkose (190) Limestone (210) Shale (220) Sandstone 350 Shale 380 Gneiss(1,500) Granite(280) 450 Limestone Gabbro (790) 180 million years ago

  18. Regional Uplift, Tilting (or folding), Erosion • Erosion surface, gap in geologic record • Continuous Sedimentation • Sedimentation ceases Formation of the Grand Canyon Quartz Sandstone (200) Arkose (190) Limestone (210) Shale (220) Sandstone 350 Shale 380 Gneiss(1,500) Granite(280) 450 Limestone Gabbro (790) 170 million years ago

  19. Erosion of horizontal beds Formation of the Grand Canyon Quartz Sandstone (200) Arkose (190) Erosion Limestone (210) Shale (220) Sandstone 350 Shale 380 Gneiss(1,500) Granite(280) 450 Limestone Gabbro (790) 160 million years ago

  20. Erosion of horizontal beds • Loss of geologic record (i.e., Arkose) • Formation of a horizontal erosion surface Formation of the Grand Canyon Quartz Sandstone (200) Arkose (190) Erosion Limestone (210) Shale (220) Sandstone 350 Shale 380 Gneiss(1,500) Granite(280) 450 Limestone Gabbro (790) 150 million years ago

  21. Erosion of horizontal beds • Loss of geologic record (i.e., Arkose) • Formation of a horizontal erosion surface • Renewed Sedimentation Formation of the Grand Canyon Quartz Sandstone (200) Arkose (190) Sedimentation (e.g., reef) Limestone (210) Shale (220) Sandstone 350 Shale 380 Gneiss(1,500) Granite(280) 450 Limestone Gabbro (790) 140 million years ago

  22. Erosion of horizontal beds • Loss of geologic record (i.e., Arkose) • Formation of a horizontal erosion surface • Renewed Sedimentation Formation of the Grand Canyon Quartz Sandstone (200) Arkose (190) Limestone (140) Limestone (210) Shale (220) Sandstone 350 Shale 380 Gneiss(1,500) Granite(280) 450 Limestone Gabbro (790) 130 million years ago

  23. Erosion of horizontal beds • Loss of geologic record (i.e., Arkose) • Formation of a horizontal erosion surface • Renewed Sedimentation Formation of the Grand Canyon Quartz Sandstone (200) Arkose (190) Limestone (140) Limestone (210) Shale (220) Sandstone 350 Shale 380 Gneiss(1,500) Granite(290) 450 Limestone Gabbro (790) 120 million years ago

  24. Formation of the Grand Canyon • Deciphering Relative Ages • Principles give sequences of geologic events • Unconformities indicate gaps in the geologic record Limestone Quartz Sandstone Disconformity Angular Unconformity Limestone Shale Sandstone Shale Gneiss Granite Limestone Gabbro Nonconformities

  25. Uplift and Erosion • As the land is lifted up by tectonic forces • A stream will attempt to maintain its base level by • Cutting down into the rocks due to accelerated erosion

  26. The Grand Staircase

  27. Eastern Zion National Park

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