• View from Sourdough Mountain Overlook  A view looking down onto Diablo Lake. Photo Credit: NPS/Michael Silverman, 2010.

    North Cascades

    National Park Washington

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  • Diablo Lake To Be Drawn Down Three Feet on Sept. 17 and Early Oct., Trailer-Launched Boats Affected

    On September 17 and October 1-15 Diablo Lake will be drawn down 3 vertical feet for facility repairs. During the drawdown, boats with trailers will not be able to launch or take boats off the water. Hand-launched vessels will still be able to launch. More »

  • Cascade River Road will be open as normal through fall/winter 2014

    Cascade River Rd. will be open in 2014 until snow conditions make it impassable to vehicles, as normal. The road closure that was planned to begin September 8 has been postponed beyond 2014 due to unforeseen circumstances. More »

  • Lone Mountain Fire - National Park Service Trail Closures

    The Lone Mountain Fire in North Cascades National Park is approximately 5 mi NW of Stehekin in the Boulder Creek drainage. Boulder Creek Trail is closed. More »

Geologic Formations

The North Cascades are still rising, shifting and forming. Geologists believe that these mountains are a collage of terranes, distinct assemblages of rock separated by faults. Fossil and rock magnetism studies indicate that the North Cascades terranes were formed thousands of miles south in the Pacific Ocean. Attached to slowly moving plates of oceanic rock, they drifted northward merging together about 90 million years ago. Colliding with the North American Continent, the drifting rock masses were thrust upwards and faulted laterally into a jumbled array of mountains. The collision broke or sliced the terranes into north or south trending faults that are still evident today.

Over time, these predecessors to today's North Cascades were further faulted and eroded to a nearly level plain. During the past 40 million years, heavier oceanic rocks thrust beneath the edge of this region. Intense heat at great depths caused them to melt. Some of the melt rose to the surface as fiery volcanic eruptions like Mt. Baker. The rest recrystalized at various depths to form vast bodies of granitic rock forming the core of the North Cascades. These gigantic pinnacles have pushed upward to majestic heights again, exposing the roots of the ancient collision zone. Scientists agree North Cascades geology comprises some of the most complex and least understood geology in North America.

Did You Know?

Did You Know?

Stephen Mather Wilderness comprises 93% of the North Cascades National Park Service Complex. About 400 miles of trail provide access to this rugged Wilderness.