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Geoscience Canada

Geology of Canadian Barry G. Warner

Volume 31, Number 2, June 2004 Article abstract Wetlands have not gained as much attention as they ought to by geologists URI: https://id.erudit.org/iderudit/geocan31_2art02 despite being so prevalent in the Canadian landscape. Some of this stems from a poor understanding of geology and what wetland landforms are. See table of contents Wetlands constitute unusual landforms in that they are formed of biological material predominantly shaped by biological processes rather than being formed of minerals and rock shaped more by physical processes. There are two Publisher(s) main groups of wetlands: mineral wetlands, commonly situated in high-energy settings; and peatlands, situated in low-energy settings that undergo either The Geological Association of Canada terrestrialization or during the course of their development. Wetlands, as both a landscape unit and economic resource, have historically ISSN been and will continue to be important in Canada. New and more specialized 0315-0941 (print) skills and engineering designs will be required to build infrastructure in 1911-4850 (digital) wetland terrain. Wetlands should be regarded as an economic resource that requires wise use and management. Nature-sensitive technologies need to be invented for use with wetlands to conserve and enhance the resource to serve Explore this journal the needs and protect the health of human society.

Cite this article Warner, B. G. (2004). Geology of Canadian Wetlands. Geoscience Canada, 31(2), 57–68.

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This article is disseminated and preserved by Érudit. Érudit is a non-profit inter-university consortium of the Université de Montréal, Université Laval, and the Université du Québec à Montréal. Its mission is to promote and disseminate research. https://www.erudit.org/en/ GEOSCIENCE CANADA Volume 31 Number 2 June 2004 57

géologues n’ont pas prêté suffisamment paleoecological tools. Further, these d’attention aux terres humides. Cela tools can be applied to elucidate more tient en partie à une mauvaise precisely what and how the geological connaissance de la géologie des terres connections are with wetlands, and what humides et de ce que sont ces éléments if any, the relationships are between the géomorphologiques. Comme éléments vast array of different wetland types. géomorphologiques, les terres humides Wetlands are intimately connected to the ont ceci de particulier qu’elles sont surroundings of their individual basins principalement constituées de matériaux and to their watersheds. The geology of biologiques issus de processus wetlands focuses on understanding these biologiques, et non de minéraux et de relationships (Moore, 2001). Geology of Canadian roches formées par des processus The importance of geology in Wetlands physiques. Il existe deux grands groupes wetland science seems to have escaped de terres humides, soit les terres the attention of most geologists, despite humides minérales, généralement situées covering about 15% and being a Barry G. Warner en milieux de hautes énergies, et les distinctive part of the Canadian land- Wetlands Research Centre tourbières, situées en milieux de basses scape. Part of the problem is that University of Waterloo énergies, et dont le développement wetlands have long been an enigma. Are Waterloo, N2L 3G1 comporte une étape de terrestrialisation they landforms, soil units, water features [email protected] ou de tourbification. or vegetation communities? The answer Tant comme élément topo- is yes, to all of the above. Wetland SUMMARY graphique que ressource économique, science can be thought of as an amalga- Wetlands have not gained as much les terres humides ont été et demeurent mation of all of these disciplines. Up attention as they ought to by geologists importantes au Canada. Des savoir- until a decade or two ago, it was not despite being so prevalent in the faire techniques nouveaux et plus possible to provide clear answers to Canadian landscape. Some of this stems spécialisés seront nécessaires pour these questions. Today, wetland science from a poor understanding of wetland concevoir et édifier des infrastructures has become more refined and widely geology and what wetland landforms are. en milieux humides. On devrait voir les accepted as a distinct and unique Wetlands constitute unusual landforms terres humides comme une ressource discipline in the environmental sciences. in that they are formed of biological économique devant être gérer avec A system, begun in material predominantly shaped by sagesse. Il est nécessaire que des the 1970s, was an important develop- biological processes rather than being technologies douces soient inventées ment for defining and recognizing formed of minerals and rock shaped pour conserver la ressource et en tirer wetlands in Canada (Warner and Rubec, more by physical processes. There are un meilleur parti tout en protégeant la 1998). Though much remains to be two main groups of wetlands: mineral santé humaine. learned about the intricacies of wetland wetlands, commonly situated in high- hydrology, biogeochemistry, and biology, energy settings; and peatlands, situated and its linkages with other environ- in low-energy settings that undergo INTRODUCTION mental phenomena such as climate, either terrestrialization or paludification Wetlands occur where an excess natural and human-induced during the course of their development. of water saturates soils and collects at disturbances, and global sea levels, little Wetlands, as both a landscape shallow depths on the land surface long advancement can be made in wetland unit and economic resource, have enough to sustain waterlogged science without regard for the important historically been and will continue to be conditions. Geological characteristics role of geology. important in Canada. New and more determine how the water reaches the Canadian geologists were once specialized skills and engineering designs land surface and where it is distributed far more involved with wetlands than will be required to build infrastructure in watersheds. Where and how water is today, and indeed, played a leading role in wetland terrain. Wetlands should be situated within wetlands, especially in wetland studies in the early 1900s. regarded as an economic resource that peatlands, is controlled by physical The early interests revolved around requires wise use and management. characteristics of the peat. Origins, geological surveys and economic Nature-sensitive technologies need to be composition and stratigraphy of wetland evaluations of peat resources in the invented for use with wetlands to deposits depends on dissolved chemicals country. There is as much need today as conserve and enhance the resource to and materials derived from erosion and there was in the early 1900s for serve the needs and protect the health of deposited from their surroundings. The Canadian geologists to be involved with human society. rate and mode by which the sediment wetlands and to re-assume their leading and peat has accumulated and role, especially in view of current RÉSUMÉ decomposed through time, and how this environmental and economic issues, Bien qu’elles constituent un trait carbon-rich material is stored are such as climate change, landscape dominant du paysage canadien, les addressed using common geological and rehabilitation, sustainable wise use of 58 economic resources, surface water and EARLY WORK IN CANADIAN OCCURRENCE AND DISTRIBUTION groundwater conservation and WETLAND GEOLOGY The general pattern and geographic protection, and public and occupational Much of the early work on extent of wetlands became much better health concerns. Perhaps the wane in wetlands in Canada focused on understood once a scientific definition interest in wetland geology in recent peatlands. Initial interests were and a wetland classification framework decades may be due to the narrow primarily from entrepreneurs and were developed for Canada (Canadian historical perception that geologists engineers who investigated ways to National Wetland Working Group, need only play a role with regard to peat mine and process peat for fuel (Warner 1988; Warner and Rubec, 1998). as an economic resource and not with and Buteau, 2000). The first Inventories reveal that about 14% of the much broader issues such as commercial peat mining operation was Canadian land surface and 125 X 106 understanding the origin, character, establishing in 1864 on a near ha is covered by wetlands, about 12% development, and management of the Victoriaville, east of Montreal, Quebec. and 110 X 106 ha of which are overall wetland resource in a country Individual operations were started in peatlands, making Canada the most like Canada, whose wetlands are vast Ontario, Newfoundland, and elsewhere peatland-rich country in the world and varied. in Quebec, but all of these operations (Fig. 1; Tarnocai et al., 2000, 2001). Wetlands have historically been ceased by 1877. About 18% of the world’s wetlands regarded as obstacles to development. Interest in the use of peat for occur in Canada (Tarnocai et al., 2001). Their widespread occurrence in this fuel was renewed in the 1890s but this These figures for the most part do not country has made it nearly impossible interest was temporary. The fledgling include freshwater wetlands along the to avoid them. Technical and peat industry at the turn of the century shores of lakes, banks of rivers, in engineering skill, ingenuity, and luck lobbied the federal government for and along the marine coasts. have been instrumental in shaping assistance. This action prompted the There is a striking match Canada as it has come to be today. Geological Survey of Canada to between the peatland map of Canada Engineers are moving away from their investigate the peat industry in Europe (Fig. 1) and a map showing areas early and more traditional approaches (Nyström 1908). The government covered by proglacial lakes and inland that focussed on draining wetlands. purchased a small peat mining plant seas (Fig. 2). The flat till plains and Plans and designs now ensure that from Sweden for $50,000 and set it up clay, silt and sand glaciolacustrine and wetlands remain intact, and indeed, in 1907 on the Alfred bog near Ottawa. glaciomarine plains laid down in large engineers are restoring and creating Scandinavian geologists were hired by inland lakes and seas created poorly wetlands. This new outlook indicates the Geological Survey of Canada to drained areas that have contributed to an acceptance of the challenges of undertake national surveys of Canada’s the widespread wetlands in Canada working with wetlands in the landscape peatland resources. A series of reports today. A notable example is in the and inventing new, more nature- were published over the next 25 years southern parts of the Hudson and James sensitive technologies and codes of or so (e.g. Anrep, 1914, 1915, 1927; Bay basins, where proglacial lake and professional practice. Auer, 1930; Haanel, 1923, 1925; seabed deposits have contributed to This paper examines what Moore, 1908; Nyström, 1908; Nyström development of one of largest peatland wetland geology is and points out how and Anrep, 1909). There was so much complexes in the world. geology is related to wetland landforms interest in peatlands during this period There are obvious anomalies, in the Canadian context. There is that a Canadian Peat Society was notably in the south-central Prairies, discussion of some of the engineering formed in 1911. This early society had southern Ontario, and the Ottawa- and environmental applications of no connection with the current St. Lawrence valleys, where there are till wetland geology. Wetland geology is far Canadian Society for Peat and plains and glaciolacustrine and glacio- more relevant than is typically assumed. Peatlands, which began in the 1970s. marine clay, silt and sand deposits but More geology needs to be included in There was little interest in few peatlands today. These regions, in high school and university courses that peatland geology during this early fact, did support widespread wetlands deal with wetlands and more wetland period outside of the Geological Survey and/or peatlands in the historical past, science needs to be included in courses of Canada. Ganong (1897) in New which subsequently became filled in, on Quaternary and environmental Brunswick and Lewis and Dowding ploughed over, and drained. These geology and courses on related subjects. (1926) in Alberta studied the regions, however, are especially good Governments at all levels need to accept stratigraphy and fossils preserved in for wetland restoration and creation a greater responsibility for ensuring care peatlands. The advent of pollen analysis because the underlying glaciolacustrine of Canada’s valuable wetland resources during this period in Europe, quickly and glaciomarine deposits provide good for future generations. Much more led to collection of peat cores and foundation material on which to re- needs to be done to increase awareness publication of the first pollen diagrams establish wetlands. Other anomalies among both professionals and average in Canada (Auer, 1930; Bowman, 1931; exist on the hyper-oceanic north coast Canadians of the relevance of linking Janson and Halfert, 1937; Hansen, of British Columbia and in Newfound- geology and wetlands as biological 1940). land and the east coast of Labrador landforms. where there are no significant GEOSCIENCE CANADA Volume 31 Number 2 June 2004 59

glaciolacustrine and glaciomarine deposits but peatlands are common. Peatlands have arisen on these coasts because a hypermaritime climate sustains abundant precipitation and low evaporation, allowing peat to form directly over the impervious bedrock. Table 1 shows how geological attributes can be used as criteria for a simple wetland classification in one part of the country. An extension of this kind of geological classification is to include sediment composition, stratigraphic, and paleoecological characteristics into what in Europe has been termed geo-hydrological or biogenetical classifications (e.g. Succow and Lange, 1984).

WETLAND LANDFORMS All landforms comprise solid material, gases and water. The most obvious Figure 1. Distribution of peatlands in Canada (after Tarnocai et al., 2000). The extent of difference between wetland landforms peatland compares well with the wetland map of Canada (Tarnocai et al., 2001), given that and all others is a predominance of about 85% of Canada’s wetlands are peatlands. The heavy lines on the map delineate the major water and organic or biological drainage basins. materials, most of which is peat, rather than the usual mineral or nonbiological materials (Warner 2003b). Some wetland landforms contain more organic material than others, and some are wetter than others, but constitute landforms nonetheless. Wetland landforms have to be treated differently from the typical mineral landforms because biological processes dominate them. Wetland landforms have two primary structural layers. There is an outer or surface layer of soil with living plants, microbes and other biota, and a deeper layer comprising the dead remains of the biological inhabitants that once were part of the surface layer. Oxygen content is many orders of magnitude greater in the surface layer than in the deeper layer. The lower boundary of the surface layer is usually indicated by the lowest position of the water table in any given year. The upper boundary may be a water surface in the case of the wettest wetlands or the top of the living vegetation canopy in the case of the driest peatlands. The presence of living biota in the surface layer has led to wetlands being referred to as living Figure 2. Distribution of glaciolacustrine and glaciomarine deposits in Canada (after Trenhaile, landforms, and as such, they are 1998). dynamic and constantly changing. 60

Table 1. An example of a geological classification of natural wetlands in the Great Lakes region

Basin type Predominant Wetland Type Examples

I. Basins of glacial origin Large basins Mineral wetland Great Lakes, , Lake Nipigon, ON Kettles Mineral wetland and peatland Olivers Bog, Cambridge, ON Depressions and drainage impedients Mineral wetland and peatland Ellice Huckleberry , Wainfleet Bog, Beverly , Mer Bleue Bog, ON II. Basins formed by river action Floodplain wetlands Mineral wetland and peatland Grand River ; Dunnville Marshes, Eramosa River Swamp, ON Oxbows Mineral wetland and peatland III. Basins formed by shoreline processes Mineral wetland Point Pelee Marsh, Turkey Point Marsh, Presqu’ile Marsh, ON IV. Basins formed by isostatic uplift Mineral wetland Holland Marsh, Cootes Paradise, ON V. Wind-formed basins Mineral wetland Sauble Beach Dunes, ON VI. Basins of biotic origin Beaver dams Mineral wetland and peatland

Two broad types of wetland landforms have been distinguished in Canada. One group is organic wetlands, typically referred to as peatlands (Fig. 3a). and some and are peatlands. Peatlands have a well-developed surface layer that has been described as having as many as six sub-units within it (Clymo, 1983; van Dierendonck, 1992). The surface layer in permanently frozen peatlands is more complicated, but probably can be thought of as having at least two distinct subunits, because the depth to permafrost table and depth to water table may be the same during dry periods and the water table can lie above the permafrost table during wet periods (Vardy et al., 2000). Water- logging or not above the permafrost table, therefore, affects oxygen conditions and the opportunity for peat material to survive decomposition and longer term accumulation. Much more work is needed to understand peat accumulation processes in permanently frozen peatlands. The term has been used to refer to this surface layer in bogs (Ingram, 1978). There is no maximum thickness for the deeper layer. Depths of 12 m have been recorded in Canada, the thickest known from peatlands in the Mackenzie River (Tarnocai et al., 2000) and from a hole near Cambridge, Ontario (Warner et al., 2004). Catotelm has been used to refer to the deeper layer in bogs (Ingram, Figure 3a. A typical wetland landform and the structure of the internal layers: peatland. GEOSCIENCE CANADA Volume 31 Number 2 June 2004 61

1978). The deeper layer determines the used to separate peatland from mineral remains on the land surface, enough to overall size, shape, composition and wetland (Warner and Rubec, 1998). support wetland biota, thereby storage capacity of the peat landform, Marshes, shallow open water, and some determining where wetlands occur in while the surface regulates the growth fens and swamps are mineral wetlands. the landscape. Climate is also and formation of peat materials and The water in both peatlands and important because it can both supply accumulation processes by selecting and mineral wetlands can be either and remove water, and so too, regulating which dead biota will reach permanently frozen, as is the case in determines how much water is stored and become stored as peat in the deeper permafrost regions, intermittently on the land surface. If either geological layer below it. frozen for some years and not others, or setting or climate does not allow water The second type of wetland only seasonally frozen. Both mineral to stay on the land surface, a wetland landform is mineral wetlands, which wetlands and peatlands can be either will not form, or if either of these have a surface layer of living biota and permanently or intermittently covered factors changes once a wetland has most often are inundated, by definition, by water for all or part of the year. formed, the wetland will cease to exist. with no more than 2 m of water. They Most peatlands develop out of have either a thin and poorly developed LANDFORM ORIGINS AND mineral wetlands. Mineral wetlands or a complete lack of a deeper layer of DEVELOPMENT occur in high-energy settings and often accumulated organic material (Fig. 3b). Most wetlands in Canada originate as exchange water with adjacent landscape In Canada, a minimum measurement of mineral wetlands. Geological setting units (i.e., lakes, rivers or oceans). 40 cm for thickness of the two layers is ensures that a steady supply of water Peatlands occur in low-energy settings and are more independent of adjacent landscape units. Site-specific features of the hydroperiod and geochemistry of the waters influencing the site will determine the specific type of peatland that will develop from the mineral wetland, be it swamp, or bog. Eventually, a deeper layer of peat will become well developed, and organic materials will continue to accumulate and be added to the lower layer during the lifetime of the peatland. Peatlands may also develop out of lakes. The term terrestrialization is used to denote the process of basin- infilling whereby a lake transforms into open water wetland and thereafter a peatland. A key attribute in the terrestrialization process is the position of the water table in the basin relative to the surface of the sediment. The water table is highest relative to the surface of the organics during the lake stage and early stages of wetland development. As organic matter continues to accumulate it reaches the water table, at which point the wetland develops into marsh, fen or swamp. The precise time at which lake becomes wetland, the timing of change from one wetland phase to another, and the nature of the final stage in the terrestrialization sequence is dependent upon the size and depth of the basin and the hydrological setting, assuming climatic factors or some other external force (e.g. human disturbances) does not interrupt the terrestrialization processes. Figure 3b. A typical wetland landform and the structure of the internal layers: mineral wetland. 62

The ongoing accumulation of of the terrestrialization or paludification in situations where wetland inception organic materials in the deeper layer pathway. Peatlands are important occurred early, but not where wetland may eventually cause a peatland to repositories of paleoenvironmental inception was delayed because climatic, outgrow the physical confines of its information (Warner and Bunting, geological, hydrological or biological basin. As the deeper layer thickens and 1996). As such, they can be long-term factors caused a lag in wetland moves out of the basin, it will essentially sensors and archives of climatic shifts formation. Such lags are probably more convert into peatland what was (e.g. natural and human-induced), common in Canada than might be originally terrestrial land around the geomorphic changes (e.g. sea levels, expected because paludification, a basin. This process is referred to as isostatic adjustments), natural major process responsible for peatlands paludification. It is possible that catastrophes (e.g. storms, hurricanes, throughout central Canada, did not overflowing peat from two adjacent volcanic eruptions), and human become widespread until Middle to basins may coalesce, thus producing a activities (e.g. early cultures, land uses, Late Holocene time in the central single peat landform out of the original pollution). The preserved disarticulated Boreal Ecozone (Vitt et al., 2000) and two smaller separate peatlands. The paleobiological indicators in the peat likely in other regions of the country large peatland landscapes and peat and organic sediment or geochemical too (e.g. Warner et al., 1991). landforms in Canada represent mature markers in the peat and deep interstitial Not all peatlands will continue to landform complexes that grew out of waters have been the primary tools for grow indefinitely so it is equally many smaller independent wetland reconstructing these past events. The important to determine the time at basins and depressions. widespread abundance of peatlands which peatland growth ceases. The age Raised bogs and some plateau makes them valuable archives of past of the surface of permanently frozen bogs are good examples of peatlands events for many periods in pre- and peatlands throughout the Arctic and that have outgrown their original basins postglacial time and at differential Subarctic Ecozones has been shown to (e.g. Warner et al., 1991). The net spatial scales for most of Canada. be many thousands of years (Zoltai and result is that the top of these landforms It would be very useful if mineral Tarnocai, 1975; Vardy and Warner, is higher in the center than in the wetlands and peatlands were unpublished). As such, some peatlands periphery. A steady supply of differentiated on geological maps. At are relict landforms, no longer actively precipitation is required to sustain the least 100 different wetland types occur accumulating peat, while other biota and peat accumulation processes. in Canada (Warner and Rubec, 1998), peatlands may even be slowly degrading, The dependence on precipitation as the Further recognition of terrestrialized some even back to their mineral only source for nutrients has led to and paludified wetlands would greatly wetland origins. Another example is specialized biota adapted to survival in refine wetland mapping and swamps in southern Ontario where the nutrient-poor growing conditions. interpretation of landscape origins. near-surface peat is old. The surface In regions influenced by layer has been “running on the spot” permafrost, water migrates along the AGE AND RATES OF CHANGE with no net addition of new materials thermal gradient from warm to cold, Wetlands represent landforms of reaching the deeper accumulation layer thereby feeding ice in the frozen core. various ages. Their organic (Warner, unpublished). The combined annual addition of peat composition presents an added benefit It is especially important to along with an expanding ice core may in that they can be used to age understand the role of humans during cause these peatlands to grow beyond themselves, their internal archival the historical past on wetland the confines of its basin and the surface records, and by inference, adjacent developmental processes. Human to grow higher than its edges. Palsas landscape units. The high-energy activities, both direct and indirect, have and high-centred polygonal peatlands depositional environment and lack of a been important in interfering with and are examples of permanently frozen steady accumulation of organic even halting developmental and peatland peatlands. materials makes it difficult to determine growth processes. Alternatively, human Terrestrialization and paludi- the age of mineral wetlands. This may activities may be responsible for setting fication processes have been going on also be a problem for peatlands whose up conditions conducive to wetland throughout all of postglacial time (e.g. early histories included a mineral formation or accelerating developmental Bunting and Warner, 1998). These wetland phase. For the most part, processes (e.g. Warner et al., 1989). processes can be quite predictable peatlands provide good dating control Geologists have an important role to provided climate, human activities or and continuous chronologies for large play in assessing human impacts on some other external factor has not time spans, if not for their entire wetlands, because not all intact wetlands altered the geological-hydrological- lifetime. are as natural or pristine as we might biological balance in the wetland It is common in geology to assume. system. However, the stratigraphic regard the age of the bottommost Clymo’s (1984) studies on peat records of many peatlands reveal that organic sediments in wetlands as accumulation and peatland growth there have been many interruptions to minimal estimates for the time of started a whole new way of thinking of this balance, which has steered off deglaciation or withdrawal of proglacial peat accumulation processes. His course the “natural” direction and rate water bodies. This may be reasonable models were applied for the first time in GEOSCIENCE CANADA Volume 31 Number 2 June 2004 63

North America on a site in New 42%? How might climate warming Buried wetlands may continue to Brunswick, the most comprehensively affect the carbon balance in these undergo decomposition and lose volume dated peatland in North America systems (Tarnocai, 1999)? decades after construction, causing (Warner et al., 1993). Subsequently, a further instability around structures. number of studies on both the short- ENGINEERING AND ECONOMIC Low-lying former wetland basins term and long-term peat accumulation GEOLOGY continue to discharge groundwater processes have been undertaken in Wetland resources are important to the around structures. Construction in and Canada (e.g. Belyea and Warner, 1996; development and economic prosperity around wetlands may lead to slope Frolking et al., 2001) but there remain of Canada and play pivotal roles in failure and flowage. The saturated considerable gaps in our knowledge supporting a prosperous and vital wetland deposits are susceptible to frost about peat accumulation processes in wetlands industry today (Warner, heave and subsequent damage to permanently frozen peatlands (Zoltai 2003a). It is difficult to avoid wetlands structures. and Tarnocai, 1975; Vardy et al., 1996). completely because they are so Many of Canada’s largest cities Peat is about 50% carbon (as dry widespread and as such present major and towns are situated along rivers and matter). To understand peat environmental and engineering coastlines of lakes and oceans where accumulation is to understand carbon challenges. The general tendency wetlands were once located. A good accumulation and storage in peatlands. historically has been to drain wetlands example is the heavily populated north Northern wetlands, especially peatlands, and convert them to dry land if they got shore of Lake Ontario, where one-time play a major role in global carbon cycles in the way. In recent years, this natural wetlands have been obliterated and climate change because they fix attitude has changed with realization of by fill or have been severely altered by carbon from atmosphere in the biomass the positive values of both natural and increased sediment loads from streams of the living vegetation. When the of created and restored wetlands. and rivers flowing into the lake, re- vegetation dies, the dead biomass adjustments to natural longshore drift eventually becomes peat in the surface Excavations and construction processes, and artificial changes in lake layer where it is subjected to decom- Wetlands pose special concern as water levels following construction of position. That fraction remaining foundation material for construction of the St. Lawrence Seaway. Thorough accumulates as peat in the deeper layer buildings, roads, pipelines, bridges, and knowledge of these new geological where it is stored for millenia. other structures. If at all possible, the processes and their interactions with the Canadian peatlands contain approxi- best solution is to excavate and remove adjacent land and runoff patterns is mately 262 Gt of organic carbon, which wetland materials altogether. In cities required to ensure successful restoration is about 59% of the total carbon stored and towns where construction has been and creation of wetlands along the in Canadian soils (Tarnocai 1998). rapid and care has not been taken to modern shorelines, which have been Canada contains about 18% of the recognize and remove wetland deposits entirely created by humans. Much has worlds wetlands (Tarnocai et al., 2001) prior to construction, or where fill has been learned about wetland restoration which means that Canada contains a been dumped on top of wetland and creation in recent decades in this significant proportion of the global deposits, buildings have been subjected heavily populated region of the country terrestrial carbon pool. Geologists have to severe structural damage by that can serve as models for other a major role to play in assessing settlement (White and Karrow, 1998). regions (Fig. 4; Canadian Wildlife peatland carbon stocks, characterizing the dynamics of carbon cycling, and developing predictive models of carbon and climate change in Canada (Gorham, 1991; Frolking et al., 2001; Blodau, 2002). It would seem there is great value in differentiating “dead” and “living” wetland landforms and giving special conservation status to those systems most active in removing atmospheric carbon and sequestering the carbon as peat. Other important questions revolve around changes between carbon cycling processes, degree of climate changes, and occurrence and distribution of permafrost. How accurate are our inventories or complete is our knowledge of the extent and dynamics Figure 4. Southward view across Second Marsh near Oshawa, an example of a restored of perennially frozen wetlands, mineral wetland along the north shore of Lake Ontario. A baymouth bar with a small opening estimated to occupy approximately (top of photograph) separates the wetland from the open lake. 64

Service 2002). Burwash, 1977; Keyser and Laforte, (Fig. 7). Despite attempts in the early The construction of roads across 1984). Similarly, special construction 1980s to construct a new highway with wetland terrain has resulted in a number designs and maintenance plans are care to preserve water flow patterns, the of problems. Historically, common required for pipelines and railroads culverts still shifted and sank below the practice was to lay down timbers to constructed across permafrost- surface. Massive landslides continued form a corduroy road bed (Fig. 5). influenced wetlands (Burgess and to carry the highway into the adjacent Natural drainage is commonly Tarnocai, 1997). Gulf of St. Lawrence. The highway obstructed by roads, leading to flooding Construction of provincial developed large potholes and irregular on the upstream side of the road and highway 138 between Sept-Îles and bumps and hollows. Thus, a new drying out on the downstream side if Havre St. Pierre on the north shore of highway was again attempted in the natural surface and subsurface flows are the Gulf of St. Lawrence is a good early 1990s, this time farther inland not preserved by the installation of example of problems associated with from the Gulf of St. Lawrence, where it culverts and other structures. If the road construction unique to peatland might be less prone to landslides. It soft, compressible peat is not removed terrain. Roads that settle, sink or slide took three years to build because extra prior to construction (Fig. 6), the road in this region have been constant loading was used to allow the roadbed can and settle because of sources of frustration to engineers to settle gradually before laying down differential dewatering, decomposition, the hard surface. Problems appeared and degassing of underlying organic within two months of the road opening. deposits. Also, it is possible that new Many of the bog pools surrounding the wetland plants will colonize the ditches highway dried up. Later investigations and roadsides immediately after proved the existence of widespread iron construction, growing so rapidly within oxide placic layers that were impervious a single season or two that they block to the peatland waters above in the culverts and other drainageways. This natural terrain. Under the placic layers problem can lead to flooding of the road were 10s of meters of stratified or erosion problems. Also, special glaciodeltaic sands and silts. It was later designs of roadbed through wetlands in determined that road construction itself permafrost terrain are required to Figure 6. Photograph taken in 1940 of or subsequent vibrations of traffic using protect the thermal regime in the construction of a road through a peatland in the highway pierced the iron oxide underlying substrates (e.g. Radforth and the vicinity of St.-Ulric near Matane on the placic layer, allowing water from Gaspé Peninsula, Quebec. Peat was cut and peatland pools to drain into the removed by hand to near the mineral base. underlying sand and silt, thereby A bed of gravel was then laid down and an causing the sand and silt to liquefy and asphalt surface was then applied on top of fail. Had geologists and engineers been the gravel. (Photograph courtesy of P. aware that iron oxide placic layers are Buteau, Quebec Ministry of Natural common phenomena associated with Resources). peatlands, they might have known what to look for in the field and be better prepared to take precautions to preserve them.

Water resources Wetlands contain large quantities of water and regulate both surface and groundwater flows of water that would otherwise run off rapidly. Historically, a great deal of effort was directed towards drainage and increasing runoff within and around wetlands. The result has been a distortion of runoff patterns, Figure 7. Oblique aerial photograph land drainage, flooding, channelization, looking north of Hwy. 138 between Sept- alteration of water ages, and inter- Iles and Havre St. Pierre, Quebec. The earlier catchment water transfers of surface abandoned highway with several large waters in watersheds of the country. failures exposing the underlying glaciodeltaic Figure 5. An abandoned corduroy road Wetlands may overlie important Figure 5. sand deposits is located next to the Gulf of constructed in the early 1900s across groundwater aquifers, especially on St. Lawrence. The new highway is farther peatland on Graham Island, Queen moraines, eskers, and fluvioglacial north with small washouts exposing sand Charlotte Islands, British Columbia. along it. deposits. One such example is the Oak GEOSCIENCE CANADA Volume 31 Number 2 June 2004 65

Ridges moraine north of , which Mining Peat is also processed into a supports numerous wetlands and Commercial mining of peat started in number of products some of which have important aquifers used by the dense 1864 in Quebec (Warner and Buteau, been tried but not all of which have population around it (Sharpe et al., 2000). Early activities were for peat become commercially viable in Canada 2002). fuel, but Canada overtook the world (Table 2). Such products include peat The complex biogeochemical market for horticultural peat after pots, boards, pellets, briquettes, soil transformations that occur in wetlands World War II when European supplies conditioners, fertilizers, carbon-based have the ability to attenuate were no longer available. Ontario and filters, and golf tees. Peat-based contaminants in runoff waters coming British Columbia were once the leading compounds have been used for from a variety of human activities. peat-producing provinces. Ontario had medicines and therapy (i.e. peat baths), Therefore, wetlands are important for 11 commercial peat operations and growth stimulators, food additives (i.e. protecting surface and ground waters today has none. Some of these yeasts, carbohydrates), waxes and and drinking water supplies (i.e. Devito operations might have survived if they sealers, lubricants, and reagents, which et al., 2000). had done the necessary geological have been extracted from Sphagnum Dam and reservoir construction fieldwork to characterize the peat and peat. may destroy large areas of wetlands and the nature of the deposit more carefully, Mining of peat and wetland contribute further to distorting runoff rather than simply assuming that all deposits as “black earth” for gardens volumes and patterns. There is special peats were the same. and potting mixes continues in many concern, especially in the central part of Quebec, New Brunswick and regions on a small scale. This activity the country where reservoirs for Alberta are the three leading peat- can create problems for wetland hydroelectricity flood wetlands. Other producing regions today (Keys, 1992). conservation near densely populated water level control structures may alter Peat mining is concentrated on the regions, where many wetlands have natural water levels that cause changes plateau and raised bogs along the north been lost or altered by humans. to natural wetlands (Fig. 8). Flooding and south shores of the St. Lawrence induces a change in redox conditions in River and around the Gulf of St. Agriculture organic soils that mobilizes and converts Lawrence. The wet and cool oceanic The rich nutrients and abundant water natural mercury into methyl-mercury, climate readily supports fast-growing where mineral wetlands and peatlands which becomes readily available to Sphagnum mosses, peat-forming with alkaline soils were cleared and reservoir biota, including fish, and processes and development of peat drained support some of Canada’s most humans who eat the fish. Flooding may landforms. Raised bogs that developed productive vegetable and fruit growing increase greenhouse gas emissions on clay deposits of the ancient areas (Table 2). The Holland Marsh on (Rosenberg et al., 2000). Flooding by LaFlamme Sea in the Lac St. Jean the southern edge of the Lake Simcoe hydroelectric reservoirs is especially Region of Quebec have given rise to basin was originally a Carex rostrata fen detrimental to permanently frozen good peat deposits. Basin bogs and and Alnus swamp in the early 1900s, peatlands because the overall permafrost swamps are being used in the vicinity of before farmers established vegetable regime is completely altered or Edmonton for horticultural peat, where gardening for the southern Ontario obliterated. the hot dry summers in western Canada market. The bogs, fens, and estuarine facilitate its drying and collection. marshes in the Lower Fraser Valley and

Table 2. Some uses of wetlands.

INTACT STATE • Recreation (walking, hiking, fishing, hunting, wilderness trekking, camping, education • Management areas (forestry, watershed planning, flood control • Conservation areas and reserves (nature preserves, parks, biodiversity reserves, wildlife habitat, aquifer protection) • Climate change mitigation areas (carbon sequestration sites)

MANAGED STATE • Agriculture and horticulture (blueberries, cranberries, market vegetables, flowers, bulbs, sod farming, livestock) Figure 8. Aerial view of round bulrush • Forestry and afforestry (Scirpus) in open water wetland areas of Lake • Recreation (education, demonstration sites) Abitibi in northern Ontario thought to have • Development (urbanization, residential areas) formed by artificial water level controls at the • Primary peat reserves (raw materials, horticulture peat moss, peat-based by-products) outlet of the lake. (Photograph courtesy of B. • Secondary peat reserves and peatland management areas (raw materials, horticultural peat Burkhardt, Ministry of Natural Resources, moss, peat-based by-products) Timmins). 66

Fraser Delta of British Columbia deal with environmental pollution, geologists need to be aware of because support large vegetable growing water-control problems, biodiversity it is probably only a matter of time operations. Where peat soils are more and habitat issues. There is a wide before Canadians may be confronted acidic, such as in Newfoundland, range of designs that can vary from with similar problems. For example, crushed limestone and fertilizers are being relatively low-energy demanding there is a large oxygen depleted zone at added to make them suitable for the systems through to ones that are very the mouth of the Mississippi River in same kind of crops. sophisticated wetland systems requiring the north-central Gulf of Mexico that The acidic and peat-rich soils of manufactured energy and continuous has caused major economic losses to bogs in southern Nova Scotia, the Lac maintenance to operate. fisheries. The “dead-zone” is attributed St. Jean region of central Quebec and Drought conditions in the 1930s to agricultural nutrients and high interior British Columbia support some in the Prairies caused many wetlands to sediment input brought about by the of the largest cranberry growing disappear (Leitch, 1978). Catastrophic loss of wetlands throughout the entire operations in the country (Fig. 9). population declines in waterfowl and Mississippi basin (Rabalais et al., Cranberry production on peatlands in other wildlife dependant upon wetlands 2002). A major program has been the Lower Fraser Valley represents were common. This necessitated initiated to restore wetlands throughout British Columbia’s largest berry crop. restoration of wetland habitat. Thus the whole , especially in Cloudberry (Rubus chamaemorus) and began the use of wetland ecotechnology riparian zones along stream and river thimbleberry (Rubus idaeus) are techniques in Canada. Wetlands have courses to control erosion and nutrients harvested from bogs in Quebec for been used to rehabilitate quarries, reaching the Gulf of Mexico (Mitsch et juice and liqueur production. Wild-rice aggregate pits, tailings and al., 2001). It is not that long ago that (Zizania aquatica), another wetland abandoned mine sites – other ways of Lake Erie was considered “dead”. How crop, is harvested on a commercial repairing degraded landscapes and can we best use wetlands in Canadian basis in the marshes and open water reversing historical trends of lost agricultural landscapes to help with wetlands of northwest Ontario and wetland habitat. controlling runoff and attenuating southern Manitoba. Wetland technology as a passive, nutrients? Might more wetlands have above ground alternative to helped to protect surface and drinking Wetland Ecotechnology conventional wastewater treatment and water supplies from deadly agricultural- Ecological engineering, also referred to water quality improvement system is derived pathogens in the Walkerton as ecotechnology, is an emerging new gaining much attention. The first disaster? field in Canada (Warner and Li, 1998; systems were constructed in 1979 in Mobilization of natural mercury Kells and Warner, 2000). This Ontario and Saskatchewan (Kells and and its entry into the human food chain technology is fast becoming the way of Warner, 2000). Today there are by hydroelectric reservoirs flooding of the future to bring the needs of human hundreds of fully-operational, pilot scale peatland terrain is another way that society together with the need of and experimental systems across the wetlands relate directly to human health maintaining a healthy living country. issues. The natural source of the environment. Wetlands ecotechnology mercury has not been confirmed in all combines engineering design and CONCLUSIONS cases, though it is suspected to be in the modeling principles with concepts of Canada contains more wetland than any parent soils and bedrock and undergoes applied and fundamental ecology by other country in the world, and geochemical transformation when soils creating systems that duplicate or Canadian geologists and engineers have become anaerobic by flooding (St. simulate natural wetland systems while an opportunity and responsibility to Louis et al., 1994). performing specific needs of humans. take a lead in advancing wetland When they are set ablaze, Wetland ecotechnology can be used to knowledge and technological develop- wetlands pose serious natural health ment. Geologists have a role to play in hazards by contributing smoke and our national carbon inventory because haze. The burning peatlands of south the net carbon stored in our wetlands Florida, USA, Kalimantan, Indonesia, greatly exceeds the carbon stored in our and around Moscow, Russia are recent forests and agricultural soils. How or if examples of global significance wetland carbon is priced in economic illustrating the magnitude of threats to terms for sale and trade on the world human health. Many of the forest fires market has yet to be determined, but that occur annually in northern and could prove to be important in assisting central Canada include peatlands. Canada to meet its international Fires, large and small, are important for obligations to off-setting carbon the ecological integrity of many natural emissions now that Canada has ratified ecosystems including wetlands, but the the Kyoto Protocol. magnitude and intensity of fires, Figure 9. A typical cranberry farm on There are a number of major exacerbated by drought conditions in peatland during harvest near Bala, Ontario. wetland issues in the world that recent years, will continue to require GEOSCIENCE CANADA Volume 31 Number 2 June 2004 67 watchful care in the near future. Widespread spring flooding, Canadian Journal of Botany, v. 74, p. 366- Coastal wetlands along the eastern which seems to be common in Canada, 377. seaboard of the USA are being eroded is a direct result of the way humans Blodau, C., 2002, Carbon cycling in peatlands – A review of processes and controls: at extremely high rates for reasons not have modified the natural land surface. Environmental Reviews, v. 10, p. 111-134. yet clearly understood (Hartig et al., Would more wetlands and natural Bowman, P.W., 1931, Study of a peat bog near 2002). The problem has recently vegetation cover have been able to store the Matamek River, Quebec, Canada, by attracted the media attention with more spring meltwater, reduce surface the method of pollen analysis: Ecology v. feature presentations by CNN flows, and save the enormous property 12, p. 695-708. Television. Is it possible that parts of loss in such recent floods as in the Bunting, M.J. and Warner, B.G., 1998, Hydroseral development in southern the Canadian coast and its wetlands Saguenay area of Quebec or around Ontario: Development and controls: farther north are disappearing at similar Winnipeg and the southern Prairies? Journal of Biogeography, v. 25, p. 3-18. rates? High peat cliffs on the coasts of Every Canadian probably comes Burgess, M.M. and Tarnocai, C., 1997, New Brunswick and Prince Edward in contact with wetlands, either directly Peatlands in the discontinuous permafrost Island are clear examples of coastal or indirectly, on a daily basis. zone along the Norman Wells pipeline, wetland loss by transgressing sea levels Wetlands are distinctive features of the Canada, in Iskandr, E.A., ed., Proceedings of (Fig. 10). Canadian landscape and are part of our the International Symposium on Physics, Chemistry and Ecology of Seasonally Frozen Wetlands are central to terrestrial identity. We have always had to deal Soils, Fairbanks, Alaska: U.S. Army Cold water cycles. Damming of rivers with wetlands, whether we wanted to or Regions Research and Engineering continues to be a problem because it not, and we will continue to need to do Laboratory Special Report 97-10, p. 417- changes river flow volumes, increases so. Wetland geology is probably more 424. time taken to drain to the oceans which important than ever because we now Canadian National Wetland Working Group, causes the water to age and change know that wetlands are unique and 1988, Wetlands of Canada. Polyscience Publishers, Montreal, 452 p. ecosystems, and there are alterations to distinctive parts of the landscape and Canadian Wildlife Service, 2002, Where land natural biota and biodiversity. River specialized knowledge and skill is meets water: Understanding wetlands of the diversions and channelization may required to deal with the many new Great Lakes: Canadian Wildlife Service, connect flows across drainage divides. environmental and economic issues that Environment Canada, Downsview, Ontario, In many parts of the world, water will be facing Canadians in years to 72 p. control structures have fallen into come. Clymo, R.S., 1983, Peat in Gore, A.J.P., ed., Ecosystems of the world: : swamp, disrepair and require replacement or bog, fen and moor, 4A: Elsevier Scientific renovation. The alternative is to ACKNOWLEDGEMENTS Publishing Co., Amsterdam, p. 159-224. abandon the structures, which presents Many of the ideas presented in this Clymo, R.S., 1984, The limits to peat growth: the need to restore rivers and clean old paper have been generated by research Philosophical Transactions of the Royal reservoirs. Wetlands should be undertaken with support from the Society of London, Series B, v. 303, p. 605- considered in the context of both cause Natural Sciences and Engineering 654. Devito, K.J., Fitzgerald, D., Hill, A.R., and for change and consequence of such Research Council of Canada. 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