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

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
	Igneous rocks Sedimentary Rocks Metamorphic 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
	Nooksack terrane Chilliwack River terrane Bell Pass mélange Easton terrane Something extra: Sand in the sea: how does it move?
	Rocks of the Metamorphic Core Domain
	Something extra: Making Sense of Terranes Chelan Mountains Terrane Nason Terrane Swakane terrane Little Jack terrane
	Rocks of the Methow Domain
	Hozomeen Terrane Methow Terrane Something extra: Breaking and Folding the Rocks of the Methow Domain
6) Annealing the Parts
	Metamorphism
	Stitching Plutons
	The Skagit Gneiss Complex
	Something extra: Orthogneisses and Migmatites
	More Metamorphism
7) Shifting The Pieces
	Northward Drift
	Evidence from old faults Evidence from tectonic plate motions Evidence from paleomagnetism Something extra: Paleomagnetism: Finding a Rock’s Place of Birth
	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
	Formation of Glaciers How a Glacier Sculpts and What It Leaves Behind Scenery Born of Ice
	The Work of Gravity
Glossary

Virtual Geology Field Trips Field trip map 1; Highway 20 and vicinity Stop 1 - The town of Concrete Limestone quarry at Concrete and Ice Age dam Side trip A - Sauk Mountain Views and remnants of old volcanoes Stop 2 - Newhalem Dating ancient magma using the zircon radiometric clock Stop 3 - The Anomalous Skagit Gorge Turning the River Around Stop 4 - Diablo Dam Damming a canyon of stretched granite Stop 5 - Diablo Lake Overlook Rocks and glaciers behind the scene Side trip B - Ross Lake Boat Landing Finding marble in the Skagit Gneiss Side trip C - Ruby Mountain A long climb and a huge fold Stop 6 - Western Ross Lake Overlook Views of faulted terranes Stop 7 - Crater Mountain Views of an ancient ocean floor Side trip D - Easy Pass A groovy fault Side trip E - Maple Pass Views of a wandering batholith Stop 8 - Washington Pass Overlook Granite inspires Field trip map 2; Baker River Stop 9 - Burpee Hill The Puget Lobe outwash Stop 10 - Schriebers Meadow Road Sulphur Creek lava flow and its future Side trip F - Ancient rocks along the Park Butte Trail Long history in a block Side trip G - Railroad Grade View from atop a glacial moraine Stop 11 - Anderson Creek Road overlook A geologic potpourri Side trip H - Anderson Butte A view of Bacon Peak and its cap of Eocene sediments Field trip map 3; North Fork of the Nooksack River Stop 12 - Church Mountain Landslide A catastrophic event Side trip I - Yellow Aster Meadows Home of the Yellow Aster Complex Side trip J - Twin Lakes Road Cutting the deck Side trip K - Twin Lakes Ancient volcanic rocks and a glacial pass Side trip L - Lone Jack Mine and a view of Big Bosom Butte Gold and an ancient caldera Side trip M - Nooksack Cirque Amphitheater carved from nested plutons Side trip N - Hannegan Pass Finding the age of an old volcanic caldera Stop 13 - Artist Point Old volcanoes Side trip O - Lake Ann Trail A geologic panorama of the last 225 million years

| North Cascades geology home | North Cascades National Park home | | Geologic & Field Trip Maps | North Cascades geology field trip |

| USGS Geology in the Parks home | NPS Park Geology Tour home | 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! parkgeology@den.nps.gov http://www.nature.nps.gov/grd/usgsnps/noca/content.html This page was last updated on 12/1/99

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