Matier Glacier EarthCache
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Located northeast of Lillooet Lake and southwest of Duffy Lake is Joffre Lakes Provincial Park. Within the park is Mount Matier, a fine peak offering a number of snow and rock routes encompassing a variety of moderate to difficult grades. Summit views are wide ranging, as this is the highest peak in the Joffre Group. Likewise, Matier is a landmark peak which can be seen from many other summits in the range, and picked out from a considerable distance.
Crowning the massif is the Matier glacier, an impressive alpine glacier dating back to the last ice age which occurred during the Pleistocene epoch some 20,000 years ago. If you look upon the edge of the glacier during the fading light, you will see the true color of the inside of the glacier.
Joffre Lakes park & trail: Steeply rising from Lower Joffre Lake, the glacier-laden peaks are visible from an easily accessible viewpoint 500 meters from the parking lot. If you carry on, the trail becomes a rough, rocky and steep hike through the Coast Mountain range. Evidence of the park’s glacial history can be found in the U-shaped valleys, glacial silts and lateral moraines. This magnificent area of jagged peaks, icefields, cold rushing streams and turquoise blue lakes was established as a recreation area in 1988 and became a Class A park in 1996. A highlight of the park is the turquoise blue waters of Lower, Middle and Upper Joffre lakes, all three of which are located along the trail, and each more stunning than the last. Joffre Lakes Provincial Park has opportunities for hiking, camping, mountaineering, wildlife viewing, and fishing. More information on the hike/trail available at Vancouver Trails.
Earthcache ground zero: The coordinates will bring you to a small prominence aside from the campground, where many of the geological/glacial features can be photographed from a safe distance. The coordinates are just a rough guideline, essentially a spot where you can make a visual survey of the area and pick your approach to any feature you spot. Those who wish to venture close to the glaciers edge or on top of it should do so only with the proper equipment & experience in mountaineering. For exploring the steep southeast area, please exercise the essentials of hiking.
Important Glacial Processes
Ablation Zone -Lying below the currently active snowline, the ablation zone contains meltwater streams and calving events. The zone moves along the surface of a glacier depending on annual net gain or loss of snow & ice. When accumulation < ablation, the glacial mass decreases and recedes uphill.
Accumulation Zone -Lying above the currently active snowline, the accumulation zone is where the glacier transforms precipitation into glacial ice through the snow-ice transformation. When accumulation > ablation, the glacial mass increases and flows downhill.
Compressive Flow - When an area of a glacier decelerates with decreasing slope or thickness, crevasses can be sealed and debris carried from the base of a glacier to the surface.
Extending Flow - When an area of a glacier accelerates with increasing slope or thickness, erosion will increase, crevasses will crack open, and ice falls become more frequent.
Glacier Mass Balance (Inputs vs. Outputs) -
Inputs [solid precipitation (mostly snowfall) + blown snow + snow avalanches] - Outputs [melt + evaporation/sublimation + calving]
If Inputs > Outputs = positive mass balance, thus the glacier expands
If Outputs > Inputs = negative mass balance, thus the glacier retreats
If Inputs = Outputs = balance, thus the glacier is at a standstill, but still moving.
The larger the glaciers the more delayed is the response of the terminus to a change in mass balance, up to a thousand years for a continental ice sheet, but for an alpine glacier the size of Matier, the response can be within 10-20 years.
Névé - Fresh snow that has fallen upon the accumulation zone, and has been melted, refrozen, and compacted. It's density has increased, and thus is disliked by skiers for its hardened character.
Pleistocene epoch - A time period in Earth's history from approximately 2.6 million years ago to 12 thousand years ago. This stretch of time saw North America and much of Eurasia undergo repeated ice ages that severely altered surficial landscapes. Remnants of those ice ages can be seen in a multitude of valley and alpine glaciers throughout British Columbia, including the Matier glacier.
Important Glacial Features
Arête - Narrow, rocky, jagged ridge which divides the steep walls of two adjacent cirques. It may be on the crestline of a mountain or on a subsidiary ridge.
Cirque - A concave, ampitheatre-like depression with steep sidewalls that was eroded to form by a downflowing glacier, which carried away disintegrated rocks from the hollow after freeze-thaw weathering.
Crevasse -A deep fissure of variable width in the surface of a glacier, caused by differential movement in the ice from shear stresses. Can be either transverse, marginal or longitudinal.
Equilibrium Line - Boundary between ablation zone and accumulation zone of a glacier, where the glacial mass undergoing seasonal melt is visibly defined by a distinct difference in shade/color.
Erratic - A large rock fragment that has been transported by a glacier away from its place of origin, and deposited in an area of dissimilar rock types.
Glacial Outwash - Sediment material deposited by meltwater streams beyond the margins of ice-sheets and glaciers.
Glacial Till - Unsorted glacial sediment moved and deposited directly by a glacial mass. Size of grains range from clay to boulders in a haphazard matrix.
Glacial Striations - A groove or scratch on the surface of an ice-abraded rock, produced by the scraping action of rocks frozen into the base of a glacier.
Hanging Glacier - A glacier or tongue of a glacier occupying a precipitous slope so that its edge is constantly calving off, possibly as small-large ice avalanches.
Horn - A steep-sided isolated mountain summit produced by the convergence of adjoining cirques, separated by steep arêtes on intervening ridges.
Ice Cave - Cavity within a glacial mass usually produced by melting next to adjacent bedrock or through the action of running water.
Massif - Mountainous mass with fairly uniform characteristics, such as bedrock type, and with clearly defined boundaries, usually delineated by river valley boundaries.
Moraines - Accumulation of rubble material (boulders, pebbles, clay) that has been transported and deposited by a glacier. Different moraine classifications are based on where along the surface or edges the material was essentially bulldozed by the glacier (terminal, lateral, medial, recessional).
Moulin - A vertical shaft or circular hole in a glacier down which meltwater pours, possibly extending down to the bedrock beneath the glacial mass.
Tarn - A mountain lake formed in a cirque that was excavated by a downhill moving glacier.
U-shaped Valley - A valley that has been overdeepened and widened by glacial erosion, thereby modifying its pre-glacial V-shape valley. Slopes become oversteepened and greater susceptibility to landslides and other mass wasting.
Logging the Earthcache:
In order to claim this earth-cache, please email Vadrosaul (via the profile link at the top of the page) with answers to the following questions. Although it is optional, pictures of you, your group at the earthcache site, and the surrounding landscape would be appreciated:
1. How far do you think the glacier has receded in the last 10 years? How far in 30?
2. What do you think gives the Joffre lakes its gorgeous turquoise color?
3. Around the campsite you might notice that occasionally a rock is rusty red as opposed to grey. This rock, which is the same type of rock as the grey ones it sits next to, was oxidized. Why is only the occasional rock oxidized and not the entire area?
4. How wide do you think the glacier was when it extended all the way down to the southeast corner of the lake? (hint: a feature listed above will provide a visual cue)
5. Describe where at least 4 of the above mentioned glacial features are in the area, either by describing relative location or by taking pictures of them.
Prize: First cacher to take a picture of the equilibrium line wins $20 online MEC gift card
References
BC Parks - Joffre Lakes Provincial Park
John B. Whittow - Dictionary of Physical Geography
Alpine Club of Canada - Canadian Alpine journal
Vancouver Trails - Joffre Lakes hiking and camping near Pemberton, BC
Dr. Johannes Koch - Glacial Processes & Landforms
BC Hydro - BC Hydro keeps an eye on shrinking glaciers
Photos courtesy Patrick Sproule
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