Proglacial Lake Arcola EarthCache
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This earthcache focuses on one aspect of Wisconsinian (10,000 years ago) glacial history- the formation of proglacial lakes. Proglacial lakes developed along the fronts of glaciers as meltwater was released by the glacier. Proglacial lakes covered thousands of square kilometres in Saskatchewan.
The weight of the glacier depressed the underlying ground. This depressed area was exposed as the ice retreated and meltwater was trapped along the edge of the glacier forming a lake. With the loss of the weight of the glacier, the land gradually rebounded upwards (isostatic uplift) and the lake drained.
Glacier meltwater was full of fine grained sediments (sand,silt,clay) produced by glacial erosion. When this material reached a lake, it slowed down and was deposited onto the lake bottom. Today these areas are flat plains composed of fine sediments with a high clay content. They form the best agricultural land in our province.
The southern edge of the Moose Mountain plateau rises 200 metres above the surrounding landscape. Seismic evidence suggests that the Moose Mountain area was an upland plateau before Wisconsinian glaciation. It is believed that the ice melted from the plateau first or it was a drift covered nunatak (ice free area) rising above the surrounding ice sheet. The glacial ice flowed around the Moose Mountain uplands: the Weyburn Lobe to the south and west and the Moose Mountain Lobe to the east. Proglacial Lake Arcola formed when melt water was trapped between the Moose Mountain plateau and the surrounding ice of the Weyburn lobe.
It is believed that Proglacial Lake Arcola existed for less than a thousand years. It was drained by the lower part of the Moose Mountain Creek to the south into the Riviere des Lacs system into proglacial Lake Souris. After the lake was drained, the present day Moose Mountain Creek began to cut into the Lake Arcola sediments. The result is a wide valley (glacial spillway) occupied by a small creek (misfit stream). The lower portion of the valley is now a lake created by the construction of the Alameda Dam in the 1990's.
From your location at the above coordinates you are standing near the edge of the proglacial lake. The spectacular view illustrates the effects of glaciation on today's landscape.
To log this earthcache, you must email me with the following:
(1) the GC number and name of the cache
(2) From your position at the above coordinates:
(a) Describe the landscape as you look to the north
(b) Describe the landscape as you look to the south
(c) Explain the differences.
(3) What is the main economic use of the land to the north? to the south? Explain the difference.
(4) To verify your visit to the area, go to the coordinates N 49 40.965 W 102 23.421. What is the name on the ranch sign to the NE of your location?
Even though the view is spectular, DO NOT post any pictures that will give away the answers. Incomplete or incorrect answers will be deleted. When you finish your earthcache, continue north on the road and visit the caches on Saskairie (GC1THRP and GCRNTF)
REFERENCES :
Christiansen,E.A., 1956 Glacial Geology of the Moose Mountain Area Saskatchewan, Department of Mineral Resources, Government of Saskatchewan
Encyclopedia of Saskatchewan, Proglacial Lakes, esask.uregina,ca/entry/proglacial_lakes.html
Storer,J.,1989,Geological History of Saskatchewan, Saskatchewan Museum of natural History
Additional Hints
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Treasures
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