The Origin of an Alpine Lake

Despite the area’s formidable topography, the North Cascades are filled with lakes. On a hike late last summer, I glimpsed how many of them formed.

Monogram Lake sits in a small basin perched a few thousand feet above Cascade River. At this elevation, just shy of 5,000 feet above sea level, it’s surrounded by blueberry meadows and scattered woodlands of mountain hemlock and Pacific silver fir. It’s an inviting place to camp for a couple of nights, no matter if you want to lounge by the lakeside or strengthen your quads further by climbing to the surrounding ridges.

small lake surrounded by meadows and mountains

I hiked there late last August hoping to watch black bears feeding on blueberries. The blueberries were reaching peak ripeness when I arrived, but I found no black bears or even any fresh bear sign, so instead of relaxing at the lake I decided to explore the surround terrain and take in some of the iconic alpine views that make the North Cascades so famous.

Not having a specific destination in mind, I was free to wander. These are my most favorite hikes, when I travel more to see what might lie in front of me instead fixating on a pre-determined destination.

Bushwhacking around the lake, I passed through quiet sedge-filled wetlands…

sedge meadow and small pond in mountain basin

…stopped frequently to eat blueberries…

blueberry plants with ripe blueberries

…wandered over a gently sloping boulder field…

meadow and boulder field looking up to a mountain ridge

…to a glacier tucked in a pocket just south of Little Devil Peak.

small, mostly snow free glacier tucked in a basin below a mountain peak

Here, I ate my lunch while contemplating the scene. It was a near perfect analog for the formation of the Monogram Lake basin.

Glaciers form when snow is compressed into mostly air-free ice and attains enough mass to deform and flow. Under the influences of gravity, ice deformation (high pressure within a glacier causes deeply buried ice to behave plastically), and lubrication from water at the its bed, glaciers move along the paths of least resistance. Due to their mass and size, they become powerful agents of erosion. They entrain rock, sand, and anything else as they flow. Forced along by moving ice, rocks at a glacier’s bed are especially erosive. Glacial erosion mills rock so effectively that much is pulverized into a microscopic powder called rock flour. This is the substance that gives glacial runoff it’s milky appearance and can color lakes turquoise.

Where ice had only recently receded at this particular glacier, the bedrock recorded plenty of evidence of the glacier’s past movement.

hiking pole lying on bare rock. Rock shows faint horizontal striations.

Many faint striations were scored into the bedrock near the glacier. The striations run roughly parallel to the hiking pole.

concentric gouges in metamorphic rock

Chatter marks are small, crescentic grooves formed in bedrock by rocks frozen in ice. The rocks chip the glacier’s bed as they are forced forward. The convex face of the marks point in the direction of movement.

Since glacial erosion is most pronounced at a glacier’s base, if topography forces ice through a pinch point then it causes the glacier to carve the underlying land more deeply and quickly than at the glacier’s sides, a process called overdeepening. As ice retreats, overdeepened basins often fill with water. This is the origin of fjords and deep lake basins as well as cirques high on mountainsides.

Monogram Lake occupies a cirque, a half open and steep-sided valley or basin on the side of a mountain. Instead of a clear lake surrounded by meadows, it was once filled with ice just like the basin below Little Devil Peak.

View looking toward a lake in a glacial cirque. Deep valley and snow covered peaks on horizon.

Monogram Lake

view of glacier in mountain basin. Snow covered mountains on horizon.

The glacier south of Little Devil Peak as seen from an unnamed peak above Monogram Lake.

Uniformitarianism is a geologic principle that, in sum, means the key to interpreting the past is to understand processes that occur today. Excluding the three hydroelectric reservoirs in the Skagit Valley, glaciers carved the basins for nearly every lake in North Cascades National Park and Lake Chelan National Recreation area. Even though I wasn’t around to see Monogram Lake emerge in the wake of glacial retreat, all the evidence I needed for this process was right before me.

Gee Point

While browsing a map of the Mount Baker-Snoqualmie National Forest, I spotted what appeared to be a little used trail in a tract of the forest south of Skagit River. I quickly assessed whether it was worthy of my short list for exploration: Is it interesting and is it within cycling distance? With an affirmative yes to both criteria, I set off with my bike, Rocinante, to Gee Point.

I pedaled about eight miles south on the usually quiet Concrete-Sauk Valley Road. Only slightly rolling, this road was a good warm up for the rest of the day, which I knew would require a lot of climbing. Upon reaching the Finney Creek Road, I began a slow ascent through a mosaic of forested land—fields of stumps in recent clear cuts, thick second and third-growth stands, and occasionally a pocket of old growth forest.

view of forest area with maturing trees and recently clear cut areas

In contrast to younger forest, old-growth stands are characterized not only by large and tall living trees, but also by a complex, uneven canopy and a relatively high amount of dead standing snags and down trees. Even from a distance, the old-growth can be easy to spot once you learn to look for these signs.

view of forest with tall trees on horizon

Large trees with an uneven canopy reveal a stand of old-growth trees on the edge of a former clear cut.

Most of these old-growth trees were inaccessible from the road (perhaps the only reason they remain standing), but a few other giants were spared the chainsaw. Perhaps too dangerous to cut, or perched precariously on the edge of a cliff, or already dead, these trees stood as the last remnants of the forest that used to be.

bicycle leaning against bole of large dead tree

A few miles up the Finney Creek Road stands a giant dead Douglas-fir tree. These trees remind me that, with the exception of fire-maintained prairies and frequently flooded areas, nearly all of the Sauk and Skagit river valleys were covered with old growth trees.

Specific trees, like Sitka spruce, along Finney Creek also indicated this was often a wet place. Sitka spruce is typically found in areas with cool summers and high rainfall.

silhouette of Sitka spruce

The North Cascades, however, experience a bi-modal climate. Its cool, wet winters stand in start contrast to hot and droughty summers, and I was soon reminded of the region’s aridity even as I cycled underneath a thick canopy of needles. As the road transitioned between gravel and broken pavement, the dirt was so dry I kicked up a rooster tail of dust anytime I gained appreciable speed and each pickup truck left a cloud in their wake. (I saw about a dozen motor vehicles in this stretch of national forest. With the exception of one ATV, all were pickup trucks.)

By the time I reached FS Road 1720, I was within a few miles of Gee Point, but I still had most of the climbing ahead of me.

view of dirt road lined with thick forest

It’s a lot steeper than it looks.

The road, now completely dust and gravel but pleasantly lacking washboards, switch-backed through young, even-aged trees as it gained elevation. The terrain was changing as I climbed and signs of winter’s harshness began to appear. I crossed through an avalanche chute at least three times, which gave me an excuse to stop and catch my breath as I admired the power of snow to snap trees in half.

view of short trees caused by avalanche

Winter and springtime avalanches are a frequent occurrence in the North Cascades area, pruning any plant too tall or any too stiff to flex under their tremendous force. In summer, the brushy chutes are prime habitat for bears and I caught a glimpse of a black bear in this one.

The bright, hot sunshine and steepness of the road slowed my speed dramatically and I accumulated a sizeable escort of biting flies, but the views kept getting better, even with a slight haze from wildfire smoke.

dirt road leading toward mountain peak

To reach Gee Point though, I had to hike, so I locked Rocinante to a convenient fir tree at the end of the road and started walking. About a half mile in, I entered a beautiful, uncut forest dominated by large western hemlock and Pacific silver fir. At over 4,000 feet in elevation, which is not particularly high for the Cascades and in stark contrast to the tired burned out green of lower elevations, the forest floor had a noticeably fresh appearance.

The trail soon gained a ridge line and swung to the top of Gee Point where I was rewarded with a panoramic view.

 

The air, so calm and comfortably warm, easily could’ve induced a nap, but then I remembered that I was running low on water and time, so I reluctantly retraced my steps to the trailhead. After taking one final break to filter drinking water from Little Gee Lake, I bombed down the mountainside.

view of alpine lake and basin

On the rapid descent, I was glad to have wide 700x38cc tires to handle the rough surface and working brakes to check my speed. The ride home was quick, taking me half the time to ride back compared to riding there. When I reached home, my lower legs were caked in a fine powder. They felt worked too, but it was a good kind of tired.