Early Winters Glacier EarthCache
grossi: Thanks to the 200 people who logged this EC over the past eight years!
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From this vantage point, you'll not only be treated to
spectacular views of peaks and spires carved from granite of the
Golden Horn batholith, but you'll also see other evidence of
glacial activity. This Earth Cache is accessible as long as the North Cascades Highway (SR
20) is open. If the highway is open, but the gate to the Washington
Pass overlook is closed, it's still possible to walk down the road
to the viewpoint.
The distinctive pinnacled ridges owe their look to joints, or
cracks, in the rock. Granite batholiths cool and crystallize under
considerable pressure within the Earth. Upon reaching the surface,
through uplift and erosion, they expand, causing many cracks to
form, sometimes in a pattern reflecting the shape of the batholith.
Joints in granite rocks are commonly at right angles, and where
vertical joints predominate, weathering produces serrated peaks and
ridges.
Some of the more prominent notches, such as those separating
Liberty Bell, Early Winter Spires, and other pinnacles, are not
joints, but small faults, as indicated by broken and ground up
granite along them. The blocks of rock on either side have moved at
least a little, and erosion has worn away the broken rock. The same
faults may be seen cutting the granite in the towers of Kangaroo
Ridge and the Wine Spires on the north ridge of Silver Star
Mountain, to the east.
Five to ten million years ago these mountains were more rounded
than they are today. Early Winters Creek on the left started
downstream from where you are standing. State Creek started in
Cooper Basin and flowed off to the right in a smooth curve around
Liberty Bell Mountain. A million years ago ice began to fill the
valleys and slowly erode away the mountain flanks. The glacier in
Early Winters Creek valley chewed its way into the divide
separating it from State Creek while a large volcano began forming
in the distance.
At the climax of the glacial period, the Early Winters glacier
broke through the ridge and captured the head of State Creek
glacier. As the combined glacier moved slowly in the new direction,
around the sharp bend of Early Winters Creek, it gouged deeper into
the valley floor, leaving a new ridge separating the two glaciers.
The low ridge is now called Washington Pass. Today, Early Winters
Creek still flows around this sharp bend and has its start where
State Creek used to be. The mountains are sharper and steeper now,
and Liberty Bell stands out distinctly.
To log this Earth Cache, please email me (through my gc.com
profile) the answers to the following questions. You will be able
to find the information at the overlook's display plaques and by
estimation.
1. What is the name of the large volcano that began forming as
the glacier in Early Winters Valley moved through the valley?
2. If you look across Early Winters Valley, you will see a rock
outcrop like the one you are standing on. These were once joined
together before they were separated by glacial activity. Estimate
the distance between that rock outcrop and the one you are standing
on.
3. Optional (but appreciated): Post photos of yourself with the
view, being sure to not reveal any answers to the questions in your
photographs.
Information for this cache page was obtained from the
informational plaques at the cache site as well as from Geology
of the North Cascades: A Mountain Mosaic by R. Tabor and R.
Haugerud, of the USGS, with drawings by Anne Crowder.
Additional Hints
(No hints available.)
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