DESCRIPTION:
Mount Shuksan, Washington

[Map,177K,InlineGIF]
Map, Mount Baker and the North Cascades, including Mount Shuksan
-- Modified from: National Park Service, North Cascades National Park

[Map,31K,InlineGIF]
Map, Mount Baker and Mount Shuksan
-- Modified from: Gardner, et.al., 1995, USGS Open-File Report 95-498

Mount Shuksan

Location: Washington State

Height: 9,131 feet (2173 meters)

Type: Non-Volcanic Peak within the North Cascades National Park.

Division of the North Cascades into the Western, Metamorphic Core, and Methow Domains is a start at understanding North Cascade geology, but as each domain is a mosaic of several terranes, brought together along a variety of faults, the rock-alert traveler needs to know something about the numerous terranes. ...

The Western Domain in the North Cascades also has a large-scale layering, but each layer is a terrane and the layers were stacked on top of each other by faulting in a relatively short time, geologically speaking, probably on the order of a few hundred thousand to a few million years. Furthermore, the youngest layer is not on top, but at the bottom. The terranes of the Western Domain have been thrust over each other, probably at the western edge of the North American continent as it collided with another tectonic plate. ...

The uppermost terrane in the Western Domain, the Easton terrane, was originally oceanic basalt and overlying deep-ocean mud and sand. The basalt became what has long been called the Shuksan Greenschist; and the overlying sediments became what is known as the Darrington Phyllite. The metamorphosed basalt is not everyday greenschist. Shuksan Greenschist locally contains some unusual blue amphiboles, and the phyllite contains the uncommon mineral lawsonite. ...

Mount Shuksan, carved from Shuksan Greenschist ...

Ned Brown (professor of geology at Western Washington University and an ardent fan of the Shuksan Greenschist) and his colleagues have determined that the original ocean-floor basalt and overlying mud and sand may have formed about 150 million years ago (Jurassic). They were metamorphosed some 30 million years later, in the Cretaceous Period.

Return to:
[Mount Shuksan Menu] ...
[North Cascades Menu] ...
[Mount Baker Locale Menu] ...