Walk away quietly in any direction and taste the freedom of the mountaineer. Camp out among the grasses and gentians of glacial meadows, in craggy garden nooks full of nature’s darlings. Climb the mountains and get their good tidings, Nature’s peace will flow into you as sunshine flows into trees. The winds will blow their own freshness into you and the storms their energy, while cares will drop off like autumn leaves. As age comes on, one source of enjoyment after another is closed, but nature’s sources never fail.
- John Muir, Our National Parks
Going to the mountains is a pilgrimage. For as long as I can remember, the mountains have provided a haven, a place for contemplation, a respite from the the ordinary. In younger days it was the Cascade Range, with its volcanic edifices atop a basement of older plutons and metamorphic rocks. Then later the volcanic landscapes of the Oregon Cascades, the stacked metasedimentary rocks of the Canadian Rockies, the Overthrust Belt of western Wyoming. and the remote reaches of Alaska’s Brooks Range. It is relatively recently I discovered the varied mountains of California, including the starkly beautiful ridges and valleys in the Transverse Range and Santa Monica Mountains.
The granite landscape of the Sierra Nevada draws me in. At first glance, the rocks are uniform. Taking the time to really look one starts to see subtle differences in texture, color, and how they respond to weathering. A background in geology definitely helps in seeing diversity in a seemingly endless gray-white landscape. Climbers have a better sense of the geology than the casual observer as their life may depend on their ability to “read the rocks.”
Yosemite always beckons. For the first time in over a year, I heeded the call.
Cathedral Peak and Upper Cathedral Lake from Cathedral Pass
Even in fall the Cathedral Lakes trail has upwards of a hundred people following Muir’s admonishment. The trail to the lakes, and above to Cathedral Pass cross the Cathedral Peak Granite, a marvelous rock with very large megacrysts of the mineral orthoclase, a potassium-rich feldspar. These crystals are pervasive in the rock, with many areas where you find large masses of these 2- to 4-inch crystals. The orthoclase is more resistant to weathering than the surrounding smaller crystals, forming knobby surfaces. Glacially polished surfaces show no preference for orthoclase or groundmass, they both polish up equally well.
Weathered Cathedral Peak Granite with knobby orthoclase megacrysts
Glacial polished Cathedral Peak Granite
When hiking the trails of Yosemite, one is never alone. Which made a hike to Mono Pass, then onward to Parker Pass all the more notable. It was a solitary hike, with only the rocks, stunted trees in the high country, raucous Clark’s Nutcrackers, and the wind for company. It was not until the last hour of the hike, on the way back to the trailhead, when I encountered another hiker, then saw five other people within the space of a half mile.
The hike to Mono and Parker Passes takes one into the country rock which surrounded the granite masses when they were intruded. Dark, gray and red, these rocks are metamorphosed sedimentary and volcanic rocks far older than the granites. At times it was easy to see the contact zone between the two types of rocks, which provides a sense of some of the dynamics that took place when the granites were intruded. The metamorphic rocks are more easily weathered, and tend to break down into smaller fragments, which results in less craggy peaks compared to those of granite.
Mono Pass with Mono Lake in the distance
The flat expanse of Parker Pass, elevation 11,100 feet ASL
Spillway Lake at the base of the Kuna Crest; note the contrast between the dark metamorphic rocks just above the lake, and the lighter Kuna Crest Granodiorite of the ridgetop
Metamorphic rock pavement on the divide between Mono and Parker Passes
These excursions into the back country reveal the depths of time. The story of mountain building in this part of the world starts with ancient rocks which had their origins undersea and were subsequently altered through the action of heat and pressure, the emplacement of granite at a time when dinosaurs roamed a good part of the Earth, and culminates with the recent uplift associated with the formation of the basin and range province covering much of Nevada.
It is the much more recent tearing away at these mountains that created the allure drawing millions to Yosemite each year. The evidence is everywhere: from the can’t miss vertical cliffs and bare granite domes, the hanging valleys with cascading waters, to the subtle ridges of moraines left behind when glaciers retreated, and the polished rock surfaces. Weathering and erosion have left their mark on the land.
The tidings of the mountains are the very story of the Earth itself, nature’s source for the tale of deep time. It is there for all to read and hear, one just has to slow down to look and listen.
Panorama looking northwest from Parker Pass