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Geosciences LibreTexts

7.7: Activity 7F - Igneous Rocks in Yosemite National Park

  • Page ID
    14812
  • Watch this National Park Service video regarding the rocks and landscapes of Yosemite National Park. Next use the browser version of Google Earth, to visit the meadow at the base of El Capitan in Yosemite Valley. This Google view was taken using a 360° view camera. Using your mouse, pan around to examine the valley.

    1. What is the overall cross-sectional shape of the valley?

    1. U-shape

    1. V-shape

    1. What process likely formed this valley?

    1. River processes

    1. Glacial processes

    El Capitan, Half Dome, and much of the valley and park is composed of igneous rock. Below is a picture of a hand sample of this rock. No magnification is necessary.

    7.19.png
    Figure 7.19: Activity 7F, close-up of an igneous rock from El Capitan and Half Dome in Yosemite National Park.
    1. What is the likely composition of this igneous rock?

    1. Mafic

    1. Intermediate

    1. Felsic

    1. Why did you select this composition?

    2. What is the texture of this igneous rock?

      1. Aphanitic

      2. Phaneritic

      3. Vesicular

      4. Glassy

      5. Fragental (pyroclastic)

    1. Why did you select this texture?

    1. Based on the composition and texture determined above, what is the name of this igneous rock?

    Near Cathedral Peak in Yosemite National Park, the igneous rock looks slightly different. Below is a picture of a hand sample of this rock. No magnification is necessary.

    7.20.png
    Figure 7.20: Activity 7F, close-up of an igneous rock from near Cathedral Peak in Yosemite National Park.
    1. What is the likely composition of this igneous rock?

    1. Mafic

    1. Intermediate

    1. Felsic

    1. What is the texture of this igneous rock? Be specific.

    1. Based on this texture, what term can be applied to the larger pink crystals?

    1. Based on this texture, what term can be applied to the remaining smaller crystals?

    1. Notice the large, pinkish crystals. Which mineral is represented by the pink color?

    1. What is the name of this igneous rock?

    Attributions

    • Figure 7.19: “Yosemite Igneous Rock” (CC-BY 4.0; Roger Putnam, own work)

    • Figure 7.20: “Granite” (CC-BY 2.0; James St. John via Flickr)

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