As in many pursuits in life, the greatest rewards of a visit to the
Tetons come to those who expend a real effort to earn them. Only by
leaving the teeming valley and going up into the mountains to hike the
trails and climb the peaks can the visitor come to know the Tetons in
all their moods and changes and view close at hand the details of this
magnificent mountain edifice.
Even a short hike to Hidden Falls and Inspiration Point affords an
opportunity for a more intimate view of the mountains. Along the trail
the hiker can examine outcrops of sugary white granite, glittering
mica-studded dikes, and dark intricately layered rocks. Nearby are great
piles of broken fragments that have fallen from the cliffs above, and
the visitor can begin to appreciate how vulnerable are the towering
crags to the relentless onslaught of frost and snow. The roar of the
foaming stream and the thunder of the falls are constant reminders of
the patient work of running water in wearing away the “everlasting
hills.” Running his hand across one of the smoothly polished rock faces
below Inspiration Point, the hiker gains an unforgettable concept of the
power of glacial ice and its importance in shaping this majestic
landscape. Looking back across Jenny Lake at the encircling ridge of
glacial debris, he can easily comprehend the size of the ancient glacier
that once flowed down Cascade Canyon and emerged onto the floor of
Jackson Hole.
The more ambitious hiker or mountaineer can seek out the inner recesses
of the range and explore other facets of its geology. He can visit the
jewel-like mountain lakes—Solitude, Holly, and Amphitheater are just a
few—cradled in high remote basins left by the Ice Age glaciers. He can
get a closeup view of the Teton Glacier above Amphitheater Lake, or
explore the Schoolroom Glacier, the tiny ice body below Hurricane Pass.
He may follow the trail into Garnet Canyon to see the crystals from
which the canyon takes its name and to examine the soaring ribbonlike
black dike near the end of the trail. In Alaska Basin he can study the
gently tilted layers of sandstone, limestone, and shale that once
blanketed the entire Teton Range and can search for the fossils that
help determine their age and decipher their history. From Hurricane Pass
he can see how these even layers of sedimentary rock have been broken
and displaced and how the older harder rocks that form the highest Teton
peaks have been raised far above them along the Buck Mountain fault.
Of all those who explore the high country, it is the mountaineer who has
perhaps the greatest opportunity to appreciate its geologic story.
Indeed, the success of his climb and his very life may depend on an
intuitive grasp of the mountain geology and the processes that shaped
the peaks. He observes the most intimate details—the inclination of the
joints and fractures, which gullies are swept by falling rocks, which
projecting knobs are firm, and which cracks will safely take a piton. To
many climbers the ascent of a peak is a challenge to technical
competence, endurance, and courage, but to those endowed with curiosity
and a sharp eye it can be much more. As he stands shoulder to shoulder
with the clouds on some windswept peak, such as the Grand Teton, with
the awesome panorama dropping away on all sides, he can hardly avoid
asking how this came to be. What does the mountaineer see that inspires
this curiosity? From the very first glance, it is apparent that the
scenes to the north, south, east, and west are startlingly different.
Looking west from the rough, narrow, weather-ravaged granite summit of
the Grand Teton, one sees far below him the layered gray cliffs of
_marine sedimentary rocks_ (solidified sediment originally deposited in
a shallow arm of the ocean) overlapping the granite and dipping gently
west, finally disappearing under the checkerboard farmland of Teton
Basin. Still farther west are the rolling timbered slopes of the Big
Hole Range in Idaho. A glance at the foreground, 3,000 feet below, shows
some unusual relations of the streams to the mountains. The watershed
divide of the Teton Range is not marked by the highest peaks as one
would expect. Streams in Cascade Canyon and in other canyons to the
north and south begin west of the peaks, bend around them, then flow
eastward in deep narrow gorges cut through the highest part of the
range, and emerge onto the flat floor of Jackson Hole.
In the view north along the crest of the Teton Range, the asymmetry of
the mountains is most apparent. The steep east face culminating in the
highest peaks contrasts with the lower more gentle west flank of the
uplift. From the Grand Teton it is not possible to see the actual place
where the mountains disappear under the lavas of Yellowstone Park, but
the heavily timbered broad gentle surface of the lava plain is visible
beyond the peaks and extends across the entire north panorama. Still
farther north, 75 to 100 miles away, rise the snowcapped peaks (from
northwest to northeast) of the Madison, Gallatin, and Beartooth
Mountains.
The view east presents the greatest contrasts in the shortest
distances—the flat floor of Jackson Hole is 3 miles away and 7,000 feet
below the top of the Grand Teton. Along the junction of the mountains
and valley floor are blue glacial lakes strung out like irregular beads
in a necklace. They are conspicuously rimmed by black-appearing margins
of pine trees that grow only on the surrounding glacial moraines. Beyond
these are the broad treeless boulder-strewn plains of Jackson Hole.
Fifty miles to the east and northeast, on the horizon beyond the rolling
hills of the Pinyon Peak Highlands, are the horizontally layered
volcanic rocks of the Absaroka Range. Southeast is the colorful red,
purple, green, and gray Gros Ventre River Valley, with the fresh giant
scar of the Lower Gros Ventre Slide near its mouth. Bounding the south
side of this valley are the peaks of the Gros Ventre Mountains, whose
tilted slabby gray cliff-forming layers resemble (and are the same as)
those on the west flank of the Teton Range. Seventy miles away, in the
southeast distance, beyond the Gros Ventre Mountains are the shining
snowcapped peaks of the Wind River Range, the highest peak of which
(Gannett Peak) is about 20 feet higher than the Grand Teton.
Conspicuous on the eastern and southeastern skyline are high-level
(11,000-12,000 feet) flat-topped surfaces on both the Wind River and
Absaroka Ranges. These are remnants that mark the upper limit of
sedimentary fill of the basins adjacent to the mountains. A plain once
connected these surfaces and extended westward at least as far as the
conspicuous flat on the mountain south of Lower Gros Ventre Slide. It is
difficult to imagine the amount of rock that has been washed away from
between these remnants in comparatively recent geologic time, during and
after the rise of the Teton Range.
From this vantage point the mountaineer also gets a concept of the
magnitude of the first and largest glaciers that scoured the landscape.
Ice flowed southwestward in an essentially unbroken stream from the
Beartooth Mountains, 100 miles away, westward from the Absaroka Range,
and northwestward from the Wind River Range (fig. 57). Ice lapped up to
treeline on the Teton Range and extended across Jackson Hole nearly to
the top of the Lower Gros Ventre Slide. The Pinyon Peak and Mount Leidy
Highlands were almost buried. All these glaciers came together in
Jackson Hole and flowed south within the ever-narrowing Snake River
Valley.
The view south presents a great variety of contrasts. Conspicuous, as in
the view north, is the asymmetry of the range. South of the high peaks
of crystalline rocks, gray layered cliffs of limestone extend in places
all the way to the steep east face of the Teton Range where they are
abruptly cut off by the great Teton fault.
The flat treeless floor of Jackson Hole narrows southward. Rising out of
the middle are the previously described steepsided ice-scoured rocky
buttes. Beginning near the town of Jackson, part of which is visible,
and extending as far south as the eye can see are row upon row of sharp
ridges and snowcapped peaks that converge at various angles. These are
the Hoback, Wyoming, Salt River, and Snake River Ranges.