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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.

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Presentation on theme: "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."— Presentation transcript:

1 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.

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 450 Million Years Old Sandstone Shale Limestone 300 million years ago

8 Formation of the Grand Canyon Regional Uplift Tilting (or folding) Sandstone Shale Limestone Erosion 280 million years ago 1.Regional Uplift, Tilting (or folding), Erosion

9 Formation of the Grand Canyon Sandstone Shale Limestone Regional Uplift Erosion 270 million years ago 1.Regional Uplift, Tilting (or folding), Erosion

10 Formation of the Grand Canyon Sandstone Shale Limestone Regional Uplift Erosion 260 million years ago 1.Regional Uplift, Tilting (or folding), Erosion

11 Formation of the Grand Canyon Sandstone Shale Limestone Regional Uplift Erosion 250 million years ago 1.Regional Uplift, Tilting (or folding), Erosion

12 Formation of the Grand Canyon 240 million years ago 1.Regional Uplift, Tilting, or folding) causes Erosion 2.Erosion surface indicates gap in geologic record Sandstone Shale Limestone Gneiss (1,500)Granite (280) Gabbro (790)

13 Formation of the Grand Canyon Sedimentation (e.g., clay) 220 million years ago 1.Regional Uplift, Tilting (or folding), Erosion 2.Erosion surface, gap in geologic record 3.Continuous Sedimentation Sandstone Shale Limestone Gneiss (1,500)Granite (280) Gabbro (790)

14 Formation of the Grand Canyon Sedimentation (e.g., lime mud) Shale (220) 210 million years ago 1.Regional Uplift, Tilting (or folding), Erosion 2.Erosion surface, gap in geologic record 3.Continuous Sedimentation Sandstone Shale Limestone Gneiss (1,500)Granite (280) Gabbro (790)

15 Formation of the Grand Canyon Sedimentation (e.g., quartz sand) Limestone (210) 200 million years ago Shale (220) 1.Regional Uplift, Tilting (or folding), Erosion 2.Erosion surface, gap in geologic record 3.Continuous Sedimentation Sandstone Shale Limestone Gneiss (1,500)Granite (280) Gabbro (790)

16 Formation of the Grand Canyon Sedimentation (e.g., immature sand) Shale (220) Limestone (210) Quartz Sandstone (200) 190 million years ago 1.Regional Uplift, Tilting (or folding), Erosion 2.Erosion surface, gap in geologic record 3.Continuous Sedimentation Sandstone Shale Limestone Gneiss (1,500)Granite (280) Gabbro (790)

17 Formation of the Grand Canyon Shale (220) Limestone (210) Quartz Sandstone (200) 180 million years ago Arkose (190) 1.Regional Uplift, Tilting (or folding), Erosion 2.Erosion surface, gap in geologic record 3.Continuous Sedimentation Sandstone Shale Limestone Gneiss (1,500)Granite (280) Gabbro (790)

18 Formation of the Grand Canyon Arkose (190) Shale (220) Limestone (210) Quartz Sandstone (200) 170 million years ago 1.Regional Uplift, Tilting (or folding), Erosion 2.Erosion surface, gap in geologic record 3.Continuous Sedimentation 4.Sedimentation ceases Sandstone Shale Limestone Gneiss (1,500)Granite (280) Gabbro (790)

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

20 Formation of the Grand Canyon Shale (220) Limestone (210) Arkose (190) Quartz Sandstone (200) 150 million years ago 1.Erosion of horizontal beds 2.Loss of geologic record (i.e., Arkose) 3.Formation of a horizontal erosion surface Erosion Sandstone Shale Limestone Gneiss (1,500)Granite (280) Gabbro (790)

21 Formation of the Grand Canyon Shale (220) Limestone (210) Arkose (190) Quartz Sandstone (200) Sedimentation (e.g., reef) 140 million years ago 1.Erosion of horizontal beds 2.Loss of geologic record (i.e., Arkose) 3.Formation of a horizontal erosion surface 4.Renewed Sedimentation Sandstone Shale Limestone Gneiss (1,500)Granite (280) Gabbro (790)

22 Formation of the Grand Canyon Shale (220) Limestone (210) Arkose (190) Quartz Sandstone (200) 130 million years ago 1.Erosion of horizontal beds 2.Loss of geologic record (i.e., Arkose) 3.Formation of a horizontal erosion surface 4.Renewed Sedimentation Limestone (140) Sandstone Shale Limestone Gneiss (1,500)Granite (280) Gabbro (790)

23 Formation of the Grand Canyon Sandstone Shale Limestone Shale (220) Limestone (210) Arkose (190) Quartz Sandstone (200) 120 million years ago 1.Erosion of horizontal beds 2.Loss of geologic record (i.e., Arkose) 3.Formation of a horizontal erosion surface 4.Renewed Sedimentation Limestone (140) Gneiss (1,500)Granite (290) Gabbro (790)

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

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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