Hiking in Grand Teton National Park is the best way to become familiar with the geology. My son Jim (see his link for more photos from the hike) and I recently completed a three-day loop up Cascade Canyon, through the South Fork, over Avalanche Divide, and down trail-less Avalanche Canyon. This is an excellent route for observing the Precambrian rocks of the range and the effects of alpine glaciation.
We began the hike on Friday, the 13th of September (1996), after warming up the
day before with a walk to Bradley and Taggart Lakes. The weather was partly
overcast but promising, and a rainbow in the early morning light over the floor of Jackson's Hole seemed to be a good omen. However, the forecast for Saturday and Sunday called
for falling temperatures and freezing rain and snow at higher elevations. We
took the second boat of the day across Jenny Lake and at 8:45 began the hike
up to Hidden Falls, Inspiration Point, and the forks of Cascade Canyon.
Enthusiasm was the order of the day, as new vistas presented themselves along
the trail. Familiar faces periodically appeared as we, together with hikers
whom we met, moved like a giant caterpillar up the canyon, pausing then hiking,
pausing then hiking. Our occasional rest stops allowed us to take in the
beauty and to watch the occasional picas scurrying about the talus cones,
squeaking as if to announce that they were very busy preparing for the winter,
and not to bother them.
Arriving at the forks of Cascade Canyon was welcome, because we planned to have lunch there. Our internal frame packs were heavy with gear, each weighing about 60 pounds, so we were also glad to have a longer rest as we ate our beef jerky, string cheese, and granola bars, and drank our lemonade. We chatted with a father and daughter from California, on their way to her freshman year in college. Sharing stories of the trail and digging out maps to study is something of a tradition on hikes such as these.
Soon we had to be on our way, because there was still a long way to go and we wanted to find a good campsite near the fork in the trail to Avalanche Divide. The South Fork of Cascade Canyon is a stair-stepped glacial trough. Including the stretch of trail immediatly above the fork, there are five stairsteps to ascend, each one several hundred feet in relief, and each one separated by relatively flat stretches of canyon floor. The trail immediately up the South Fork from the forks of Cascade Canyon is steep compared to the gentle gradient of most of the trail in the main canyon, and I remembered from previous hikes that hiking the rest of the afternoon could become difficult and the pack would feel like a ton. My hips always seem to bother me late in the day on extended hikes such as these.
Inspiration Point, where Cascade Canyon descends abruptly to the floor of Jackson's Hole, is at 7,200' elevation, and the fork of the Cascade lies at 7,800', an ascent of only 600' in 3.6 miles. Now we were about to ascend 1,800' to the fork of the trail to Avalanche Divide in a distance of 3.8 miles. The South Fork trail has a significantly steeper gradient than the trail we just negotiated.
We began the hike after satisfying ourselves with food and rest, and ascending the switchbacks of the first step, we were treated with views down the main canyon. The weather was holding and we were exhilarated. Most hikers take the North Fork of Cascade Canyon up to Lake Solitude. In entering the South Fork, we knew we would be relatively alone. The feeling was both exciting and disturbing, to be two of only a handful of people who would be within 10 square miles of one another. The peace and solitude were gratifying, but the loneliness in the face of exploring a trail-less canyon the next day left me a bit apprehensive.
Even though Jim and I had hiked this trail together 7 years before, we had forgotten many of the details. My Dad and I had attempted this same hike, with a climb of the South Teton thrown in for good measure, back in June of 1967. Only then the trail was deep in snow from the forks upward, and we were turned back after two days, never reaching Avalanche Divide. Part of the difficulty we faced then was not being able to find the trail, another was sunburn from reflected light off the snow. In a sense, Jim and I were now completing what my Dad and I were not able to finish. Our hike was in a way dedicated to that hike nearly 30 years before. And my Dad was with us every step of the way...as he said to me in August, "one step at a time, Jim, one step at a time".
Landmarks began to come back to us as we trudged up the South Fork - first the Wigwams to our right (west), then Table Mountain looming above us. And on our left (east), views of Mount Owen and the Grand Teton and the Enclosure were ever changing. Exploring stretches of bedrock off the trail revealed glacial striations in the granite gneisses, scratched in the rock more than 10,000 years ago by glaciers which advanced and retreated through this chasm.
The rocks along the trail displayed a psychedelic pattern of small-scale folds and cross-cutting relationships between the gneissic banding and small dikes. This pattern was exciting at first and provoked considerable speculation about the trips these metamorphic rocks took down to 10 or more kilometers in the earth's crust, back up to the surface, down and back again. But after three days of eyes cast toward the ground, watching every step, this pattern grew old indeed. As a geologist, I never thought I would say such a thing.
As we neared the top of the third step in the canyon, we paused to rest and to look at the scenery. Immediately below and to the east of the trail was a lovely cascade, tumbling through gneisses which were prominently jointed. Wildflowers were still blooming high in the canyon, though they had long since blossomed and died on the floor of Jackson's Hole. And then a lone hiker passed us heading up the trail without a pack. It turned out to be Mike Gaudette, a hydrogeologist from Boise, Idaho, who had left his gear a ways down the trail and was exploring for campsites. Jim and I described the upper part of the trail and campsites around the fork to Avalanche Divide, and the stretch of the main trail above, in the vicinity of Schoolroom Glacier and on up to Hurricane Pass. Then Mike hurried on.
We too began to move again, wanting to set up camp around 5, then have our supper and to take a side trip up to Schoolroom Glacier, as our trek tomorrow would not take us by that landmark. There were still two more steps to ascend before reaching the fork of the trail, and only because we were spurred on by the prospect of supper and a restful evening did we move along at a brisk pace. Jim, as usual, took the lead, and I brought up the rear. Jim always watches out for me on our wilderness outings, and he would pause often to allow me to catch up, sometimes feigning picture taking or adjustments of his pack or whatever, so that I wouldn't feel that I was holding him up.
On our left we could see the cascades draining Icefloe Lake, a small tarn or cirque lake nestled beneath the col between the South and Middle Tetons. We planned to visit that lake the next morning, and we watched the drainage with interest, wondering what the source of all that water might look like. Above the fourth step we met Mike who was returning to retrieve his gear. He had hiked to this point from Holly Lake in Paintbrush Canyon, where he spent the previous night. His plan was to camp at the head of the South Fork, then cross over Hurricane Pass into Alaska Basin, then over the Sheep Steps into Death Canyon where he intended to spend the night on the Death Canyon Shelf. Mike was seated on a boulder along the trail, talking to another hiker. We exchanged pleasantries and pushed on up the trail. We arrived at the fork above the fifth step about 5 pm, and searched for a suitable camp site. This area is at the uppermost edge of the South Fork camping zone, and tree cover is relatively scarce. Scattered around the polished outcrops with patches of thin soils which support grass are several groves of old gnarled trees, some of which have been struck by lightening on several occasions.
We chose a site near the trail and above the fork, which lies at 9,600', and pitched the tent. I went
down to the stream that drains the lake at the foot of Schoolroom Glacier to
purify some water, and Jim began to make ready for cooking dinner. We dined on
a sumptuous and substantial meal of Sierra Chicken, prepared from a dried mix,
and washed it down with lemonade, then cleaned up and hiked the South Fork
trail toward Hurricane Pass.
Our goal was Schoolroom Glacier at the foot of the headwall through which the pass crosses. Evening light was beginning to fall, and the range to the east began taking on a soft glow. As we ascended the switchbacks to the glacial step occupied by Schoolroom Glacier, the peaks of the central Teton Range began to loom larger and larger on the horizon. From this vantage point, the crags of the sharp knife-edge ridges (aretes) were especially obvious. Even in mid-September, flowers sprouted from patches of thin soil at this high altitude.
I remarked to Jim that the glacier appeared all but dead, a fact that Jim lamented. For when a glacier disappears in our lifetime, it is gone forever in our experience. We took photographs in remembrance of this place, then exited the notch and prepared to descend the trail to camp. Light showers began to hasten our short hike down to the tent, but these same showers gave us a beautiful rainbow in the foreground of the great towers to our east. It was a sign for me...I was looking for signs of a good hike. Tomorrow would be good to us, I was certain.
Down at the campsite by 7 pm, we wandered off to the east across polished bedrock broken by patches of grass and great gnarled evergreens, and sat on a large boulder to watch for the soft golden alpine glow which ends a hikers day in the high country. We could see shadows of ridges climb upward across the cliffs of the high peaks as night began to fall. And then we were surprised by voices approaching. It was Mike and his new-found trail companion, Bob Fink. Bob was from Vancouver, Washington, where he works for a company that installs co-gen power plants. Bob and his wife had been hiking the Rockies for the past two months and had logged over 600 miles on foot. She sprained her ankle on a 6-day excursion into the southeastern wilderness of Yellowstone, and was recuperating in the campground while Bob embarked on a four-day hike through the heart of the Teton Range. He was on the third night of his trip, having come north from the Death Canyon Shelf where he spent the previous night in a violent thunderstorm. The next day he was to head into Paintbrush Canyon, then he would hike the Valley Trail to finish his trek.
The four of us visited with one another for 2 hours, talking about our experiences on the trail, about camping and hiking gear, about our families, our work, our impressions about things that were important to us. The stars twinkled above and vague images of the high Tetons loomed to the east. At one point we could see the lights of climbers descending from the Enclosure to their camp in the Lower Saddle, and I remembered the climb my Dad and I did 33 years earlier, back in 1963. We too had camped in the Lower Saddle during an ascent of the Grand Teton via the Upper Exum Ridge. And then it was time to bed down. Mike and Bob had about a quarter of a mile to hike down the trail to their campsite, and as it was dark, Jim sent a small flashlight with them. Then, snug in our sleeping bags, we slept the sleep of those who are happily tired, yet restless about the day's hiking that lay before us.
By morning, light rain had begun to fall and a mist engulfed the head of the South Fork. We arose at 7 and were soon greeted by Mike and Bob who were returning the flashlight. We visited for an hour, then ate some of our beef jerky, string cheese and granola bars, and finished our lemonade, left over from the night before. By 9 we had broken camp and were on our way, in full dress for rain...rain pants, rain parkas, rain hats, and rain flys for our packs. I put on lightweight cotton gloves in a futile attempt to keep my hands warm, but they were soon saturated and only made matters worse. So I took them off and walked with my hands in my pockets. The drizzle soon turned to sleet, then to snow as we trudged up the steep cliffs at the head of the South Fork, beneath Avalanche Divide. We were enthralled by the September snowfall and the ethereal views that emerged through the mist down the canyon. But we were also dismayed by the discomfort that the unseemly weather created.
Fortunately, by the time we reached a sharp southward bend in the trail where we were to leave the beaten path and hike to the north-northeast to Icefloe Lake, the drizzle abated and we stowed our gear beneath a large overhanging boulder. We laid out our rain gear to dry and scrambled with enthusiasm up the boulder fields on the lateral moraine that sheltered the lake on the southwest. At the crest of the moraine we were treated to an overview of Icefloe Lake (10,652') which lay dark in the shadows beneath the steep headwall that leads to the col between the Middle and the South Tetons. The south and southwest ridges of the Middle Teton looked particularly foreboding from this vantage point. The sun periodically began to peek through the veil of clouds, lighting the west ridge of the South Teton which rose directly above us to the east. We took photographs as if we would never return to this place again, then returned through snow-covered talus to the boulder and our gear. After a snack of the familiar beef jerky, string cheese and granola bars, we walked with new energy up the easy grade of the trail to Avalanche Divide. The weather seemed to be breaking, patches of blue sky were appearing through the mist, and the sun was beginning to peek through the clouds to warm our sleet- and snow-chilled bodies. We were excited!
Arriving at the divide was a real thrill - we shouted our excitement to the wind as there before us to the south and southeast was Snowdrift Lake in the cirque at the head of Avalanche Canyon. Avalanche Canyon is a trailless canyon, and not many people venture to Avalanche divide with the intention of hiking down this stairstepped trough. The divide is a col at 10,680 feet above sea level and oddly enough is cut not in ancient Precambrian gneisses, but in Cambrian sedimentary rocks. These rocks make up the imposing "Wall" which forms the drainage divide between east and west-flowing streams in the Teton Range. We alternately paused for reflection, scurried about taking photographs, and nibbled at our lunch. Beneath our feet were Cambrian shales of the Gros Ventre Formation, to our immediate east along the divide lay blocks of frost-wedged Cambrian sandstone of the Flathead Formation, and above us to the west on the col leading to the steep cliffs of the Wall were interbedded limestones and shales of the Gallatin Formation. These Cambrian sedimentary rocks are remarkably uniform throughout the Middle and Northern Rocky Mountain region, and consequently were like old friends that we were both familiar with from our time spent at the Indiana University Geologic Field Station in southwestern Montana.
Snowdrift Lake appeared somewhat dark and foreboding in the shadows of the cirque. The Sun was not yet shining full on the upper part of the canyon beneath us. We were impressed with the size of the lake. The cirque it occupies is elongate and about a mile in length, making this tarn one of the largest in the Teton Range. The lake itself is about 0.55 miles long (985 yards) and 0.21 miles wide (370 yards). Above the lake and beneath the headwall of the canyon is an extensive deposit of very hummocky glacial till, and tiny lakes occupy many of the depressions. And above Snowdrift Lake and southeast of Avalanche Divide, nestled in a depression in the glacial till at the base of the west ridge of the South Teton, lies Kit Lake. This Lake is much smaller than Snowdrift Lake and has the typical milky appearance of glacial lakes that contain an abundance of suspended particles of "glacial flour".
The Wall at the head of the canyon was as imposing as the lake. It rises above
the talus pile at its base, upward about 500 feet in a vertical cliff. At the
top of the talus beneath the Wall we could see vestiges of the old Skyline
Trail. This trail was the main route from the South Fork into Alaska Basin
until the trail was closed because of extreme danger from rock slides on the
Wall above. Indeed! Not only was rock fall a danger here, but even during the
middle of September, the trail crossed large and steep snowfields as it
stretched across the head of Avalanche Canyon on its way to a steep and high
divide at the south end of the Wall.
Eventually we turned our gaze back down the South Fork which we had just ascended. The panorama was immense, and the u-shaped form of the canyon was especially apparent. The upper part of the canyon was filled with hummocky glacial till which had not yet been removed by stream erosion. Old glacial basins rimmed by end moraines were clearly visible, but their glaciers had long since disappeared. Schoolroom Glacier was visible from this vantage point, but its days appeared numbered as it dwindles away toward nothingness in the warmer climate induced by atmospheric pollution during our industrial age. It seems odd that something that takes so long for nature to create can be obliterated in a stroke by the hand of man.
We would have stayed at the divide much longer, but our plans called for us to camp at Snowdrift Lake for the night and we still had some exploring to do. And Jim was thinking that we might even descend beneath Snowdrift Lake to the next glacial step below, occupied by Lake Taminah, to avoid spending the night in the exposed environment of the upper reaches of the canyon. Besides, the weather was so unsettled and conditions for the next day were so uncertain, that he was concerned about being trapped so high in the canyon with only one day left to hike out. The absence of trails weighed heavy on our minds at this point, so we packed up our gear and began to pick our way downward through the talus blocks of Flathead Sandstone immediately southeast of the divide. Once through the talus, we looked up at the divide and noticed that the route would have been much easier had we traversed the shale slopes southwest of the divide. So much for our trail-finding ability! Was this a bad omen for the rest of the descent through Avalanche Canyon?