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North Cascades National Park Geology:
World Class and Close to Home

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A Geology Primer for the North Cascades

1) Introduction
Something extra: Catching the clouds
Something extra: Early encounters with the rocks

2) Minerals and Rocks
  Types of Rocks
3) Geologic Time
  Climbing a Mountain of Geologic Time
  The Geologic Time Scale
  Geologic Time Scale for the North Cascades Region

4) The Basic Pattern Emerges
Something extra: Patterns in the Rocks: Geologic Maps
Something extra: An early geologist and early ideas
  Domains of The North Cascades
  Plate Tectonics and Tectonic Terranes
  Sea-Floor Spreading
  Rocks Form Where Plates Collide
  Moving Plates and Tectonic Terranes

5) Recognizing the Mountain Mosaic: Major Terranes in the North Cascades
  Rocks of the Western Domain
  Rocks of the Metamorphic Core Domain
  Rocks of the Methow Domain
6) Annealing the Parts
  Stitching Plutons
  The Skagit Gneiss Complex
  Something extra: Orthogneisses and Migmatites
  More Metamorphism

7) Shifting The Pieces
  Northward Drift
  Extension of the crust
  Something extra: Forming depressions along faults
  Caulking the Cracks
  Summing up: Why extension?

8) From the Fiery Furnace: Volcanoes and Their Roots
  Traces of the Last Volcanic Arc
  The Mount Baker Volcano
  Something extra: Making room for magma
Something extra: Making granite and its relatives
Something extra: Families of the Arc-Root Plutons
Something extra: Old Volcanoes

9) The Constant Levelers: Water, Ice, and Gravity
  The Work of Running Water
  Something extra: How Rivers Work
  The Work of Moving Ice
  The Work of Gravity

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Virtual Geology Field Trips

  • Field trip map 1; Highway 20 and vicinity
  • Field trip map 2; Baker River
  • Field trip map 3; North Fork of the Nooksack River

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    This site is a cooperative endeavor of the
    US Geological Survey Western Earth Surface Processes Team
    and the National Park Service.
    Please share your comments and suggestions with us!
    This page was last updated on 12/1/99
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    Material in this site has been adapted from a new book, Geology of the North Cascades: A Mountain Mosaic by R. Tabor and R. Haugerud, of the USGS, with drawings by Anne Crowder. It is published by The Mountaineers, Seattle