SOUTHWESTIAN: THE GREAT SAND HILLS and the alkali lakes and ponds

GeoNotes Cypress Hills and area

THE GREAT SAND HILLS

and the alkali lakes and ponds

The Great Sand Hills cover an area of 1900 sq km and are the largest single uninterrupted dune occurrences in southern Canada. Figure 1 shows the location of the Great Sand Hills and other sand hills within a 100 km radius. They are the largest area of protected prairie landscape in Saskatchewan. The area is in rugged semi-arid terrain with steeply sloping compounded parabolic dunes with less than 1% of sand exposed as active dunes. The dunes are mobile throughout the year, and less so during winter months when they are stabilized by frost. Individual dunes can rise to more than 15 m above the surrounding plains, and based on long term records can move away from the prevailing NW winds at 1-4 m/year.

Figure 1: The Great Sand Hills and other sand hills within a 100 km radius, from Peter P David (Sauchyn, 1993).

The size and number of dunes in the Great Sand Hills are dependent on climate conditions. They are drought-sensitive; however, the dunes were not adversely affected by the 1930’s drought. As the dunes move they are stabilized by vegetation on their backsides. In high moisture years and light winds, vegetation can creep on either side flank or even in front of the dune. Over the past 57 years, active dune surfaces have generally decreased in size. Before that, large active sand surfaces maintained their down windward size at the same rate as their up windward sides became established by vegetation. Most of the forward and eastward migration of the active dunes occurs in late winter and early spring, and the dryer the late winter and early spring the more is the forward movement of the dunes.

Radiocarbon dating is difficult because the dunes lack organic matter leaving researchers with a more recently developed dating method, optical dating. Optical dating determines the last time the sand particles were exposed to sunlight. This dating method revealed lower than average precipitation through the 1700s that ended in a drought in the late 1700s which lead to the reactivation of the dunes in the early 1800s. This activity lasted for 80 years before the dunes stabilized, and continued to be relatively stable since.

There are no streams, creeks, or rivers flowing in or out of the sandhills. The high water table suggests little external drainage out of the sandhills area. Rain and snow help keep the water table high which in turn helps to reinforce vegetation growth.

The sand is derived from a proglacial outwash plain and glacial lakes that formed in front of the Laurentide glacier during deglaciation approximately 15,500 years ago. According to researchers, dune activity began shortly afterward when the dunes were the most active between 15,000-5000 years before present (BP). Since then periods of drought, dune activity, more humid conditions and vegetation establishing itself prevail.

All sand dunes in southern Alberta and Saskatchewan are parabolic dunes. Parabolic dunes are rare in ‘dry sand’ desert environments; however, they are common in temperate climate regions, not because of the vegetation or dune morphology, but because of significantly more moisture content, 4-8%, in the sand. The ‘wet sand’ parabolic dunes are the opposite of the ‘dry sand’ barchan dunes of the hot dry desert. Both dune types are crescent-shaped and are defined by how they are formed in the prevailing winds (Fig. 2 and 3).

Figure 2: Parabolic dunes are ‘wet sand’ dunes commonly found in temperate climate environments, modified after Earth Science Blog.

Figure 3: Barchan dunes are ‘dry sand’ dunes commonly found in hot dry desert environments, modified after Earth Science Blog.

There are different deglaciation ages mentioned in the published literature, 15,500-13,000 BP for the Great Sand Hills and area. Geological timelines give a general idea of the progression of geological events through time, and any ages people come across are most likely within the margin of error in age calculation. These dates can also be expressed in more general terms as late Upper Pleistocene (20,000-12,000 BP). Age dating, today, is more accurate, but there is still a need to integrate older dates to offer a general timeline of an event. The more accurate dates are used for detailed analysis. It should also be noted that within the area there were several glacial readvances and retreats adding to the complication of choosing the final age of deglaciation.

In addition to the sandhills, alkali (sodium sulfate, Na2SO4, or Glauber salt) lakes or ponds are common in southern Saskatchewan. Some lakes contain minor amounts of magnesium sulfate (MgSO4 or Epson salt) which is a bi-product of sodium sulfate at the extraction facilities. Small amounts of gypsum (calcium sulfate or CaSO4.H2O) may also be present. The sulfate brine gets concentrated overtime during the summer months when evaporation exceeds precipitation and/or by winter freeze-outs that keep the brine away from circulating groundwater.

During dry periods the alkali lakes become a white lake bed with a crystalline sulfate-patterned crust on the surface. They can be seen and, if algae are present, smelled in the sandhills area, along HWY 1 between Maple Creek and the Hatton Hills, and just east of Maple Creek where 5^th Ave turns into grid road 724. On windy days white powder from the larger dry lakes gets blown upward into a white dust cloud that can be seen for several kilometers. Alkali in Maple Creek has created issues in the basements of older houses. The town is situated on a glaciolacustrine surface (a glacial lake bed) in the Maple Creek basin where pockets of alkali migrate to the surface.

Alkali lakes and ponds are considered to be post-glacial Quaternary accumulations often occupying surface depressions that overlie preglacial valleys that drain internally. Alkali deposits are not well understood, and the research remains controversial. The controversy is based on the source of the Na+(sodium), SO4- (sulfate) and other ions, and the solutions that transport the ions into the lakes and ponds where the deposits occur.

Sodium sulfate was first discovered in Austrian spring water in 1625 by a Dutch/German chemist, Johann Rudolf Glauber. He dubbed it sal mirabilis (miraculous salt) because of its medicinal qualities as a laxative. Later it was found to have other uses such as; paper making during the Kraft process, a major compound in glass manufacturing, a filler in dry detergents, dyeing of textiles, deodorizer, heat storage for heating, and a heat sink for cooling.

Sodium sulfate has been extracted from the Chaplin Lake plant since 1948. This plant is located between Swift Current and Moose Jaw. Another plant, Ingebright Lake-Fox Valley now closed, is approximately 52 km NNE of Maple Creek. Two other deposits located in a northly direction of Maple Creek are the Bitterlake deposit 32 km NW and the Vincent Lake deposit 52 km NE.

A common alkali and saline resistant plant, Salicornia rubra or Red Saltwort grow around the edges of the dry alkali lakes or ponds. Red Saltwort begins to germinate as a pale green plant when the alkali ponds and lakes begin to dry up exposing the seeds to the alkali-encrusted silt. The plant is an annual, and when it matures the stem turns a characteristic ruby red with flowers in late summer and early fall.

A dry alkali pond with a patterned surface. The mature red vegetation around the dried up pond is Salicornia ruba or Red Saltwort. Photo: Charles Kuss

A 2017 lithium geochemical survey of the Southern Saskatchewan alkali bearing lakes found the lithium levels are too low to have any economic value.

Sources:

Bimo; 7 Sodium Sulfate Functions in Daily Life - Formula - Uses - AZ Chemistry;

AzChemistry.com; May 22, 2017
Christiansen, E.A.; The Wisconsinan Deglaciation of Southwestern Saskatchewan and Adjacent Areas; https://cdnsciencepub.com/doi/pdf/10.1139/e79-079 ; Saskatchewan Research Council; Saskatoon; 1978
Department of Natural Resources; Rare Species Guide, Salicornia rubra; https://www.dnr.state.mn.us/rsg/profile.html?action=elementDetail&selectedElement=PDCHE0J020; Minnesota DNR; St. Paul, MN; 2020
Dyke, Arthur S., Prest, Victor K.; https://www.researchgate.net/publication/269875308_Late_Wisconsinan_and_Holocene_Re treat_of_the_Laurentide_Ice_Sheet_Geological_Survey_of_Canada_Map_1702A ; Geological Survey of Canada Map 1702A; Ottawa, ON; Jan 1987
Holliday, Vance T,; Eolian Processes and Sediments On the Great Plains; https://www.argonaut.arizona.edu/sites/argonaut.sites.arizona.edu/files/2018-07/Holliday1987b.pdf; Geomorphic Systems of North America; Pgs. 195-205; 1987
Kelley, L.I., Smith, J.J. and Holmden, C.; Stable Isotope and Chemical Composition of Groundwater Associated With Sodium Sulphate Deposits, Southern Saskatchewan; https://pubsaskdev.blob.core.windows.net/pubsask-prod/88445/88445-Kelley-Smith-Holmden_1998_MiscRep98-4.pdf; Saskatchewan Geological Survey; Regina, SK; Misc. Rep. 98-4; Pgs. 136-141; 1998
Lemmen, Donald, C., editor; Landscapes of the Palliser Triangle: A Field Guide to the Geomorphology and Paleoenvironmental Record of Southwestern Saskatchewan; Canadian Association of Geographers; Saskatoon, SK; 1996
Rogers, Murray C.; A Reconnaissance Geochemical Study of the Minor Elements Concentrations in Selected Sodium Sulfate-Bearing Lakes In South-Central and Southwest Saskatchewan; https://publications.saskatchewan.ca/#/products/88080; Saskatchewan Geological Survey; Summary of Investigations 2017, Vol. 2; Regina, SK; 2017
Saskatchewan Geological Survey (2020): Resource Map of Saskatchewan, 2020 Edition; https://pubsaskdev.blob.core.windows.net/pubsask-prod/112504/ResourceMap2020.pdf; Sask. Ministry of Energy and Resources, Saskatchewan Geological Survey, Miscellaneous Report 2020-1
S auchyn, David, editor; Quaternary and Late Tertiary Landscapes of Southwestern Saskatchewan and Adjacent Areas; Canadian Plains Research Center; University of Regina; Regina, SK; Pgs. 59-81; 1993
Tomkins, R.V.; Natural Sodium Sulphate In Saskatchewan; Department of Mineral Resources; Report No. 6, 2nd ed.; Regina, SK; 1954
W eir, Brian; Chapter 6: Erosion by Gravity, Wind and Ice-Wind Erosion; https://earthscience.xyz/WindErosion ; Earth Science Blog; Arizona.
Wikipedia, The Free Encyclopedia; Washington, DC; 2020
Wolfe, S.A., Huntley, D.J., et al; https://www.researchgate.net/publication/237168904_Late_18th_Century_Drought-Induced_Sand_Dune_Activity_Great_Sand_Hills_Saskatchewan ; Canadian Journal of Earth Science; Vol. 38; Pgs. 105-117; 2001

When going to the Great Sand Hills, turn right (east) onto Twp 200 (The Great Sandhills Route) at Leibenthal, SK. Drive to the end and follow the Straw Trail Road to the sandhills. Photo: Charles Kuss